The Applicant is the Republic of Mauritius ("Mauritius"). Mauritius became an independent State on 12 March 1968, prior to which it was a colony of the United Kingdom of Great Britain and Northern Ireland (the "United Kingdom"). Mauritius was previously a French colony from 1715 until 1814, at which time France ceded it to the United Kingdom.

The Respondent is the United Kingdom, which exercised colonial rule over Mauritius until its independence. The United Kingdom continues to administer the Chagos Archipelago, previously a dependency of the colony of Mauritius, as the British Indian Ocean Territory ("BIOT"). The BIOT was established on 8 November 1965.

Mauritius is represented in these proceedings by its Agent, Mr Dheerendra Kumar Dabee GOSK, SC, Solicitor-General of the Republic of Mauritius and its Deputy Agent, Ms Aruna Devi Narain.

The United Kingdom is represented in these proceedings by its Agent, Ms Alice Lacourt, Legal Counsellor at the Foreign and Commonwealth Office (the "FCO"), who replaced Mr Christopher A. Whomersley CMG, Deputy Legal Adviser, as Agent on 5 June 2014. The United Kingdom is further represented by its Deputy Agent, Ms Nicola Smith, who replaced Ms Margaret Purdasy in this position on 21 January 2015.

The dispute between the Parties concerns a decision of the United Kingdom, taken on 1 April 2010, by which it established a Marine Protected Area ("MPA") around the Chagos Archipelago, which is administered by the United Kingdom as the BIOT. The MPA extends to a distance of 200 nautical miles from the baselines of the Chagos Archipelago and covers an area of more than half a million square kilometres.

According to Mauritius, the establishment of the MPA by the United Kingdom violates the 1982 United Nations Convention on the Law of the Sea (the "Convention" or "UNCLOS"), to which Mauritius and the United Kingdom are party, and other rules of international law.

Mauritius contends that the United Kingdom is not entitled to declare an MPA or other maritime zones because it is not the "coastal State" within the meaning of, inter alia, Articles 2, 55, 56 and 76 of the Convention. Alternatively, Mauritius contends that the United Kingdom is not entitled unilaterally to declare an MPA over the objections of Mauritius in light of the undertakings made by the United Kingdom at the time of the detachment of the Chagos Archipelago, insofar as Mauritius has been endowed with certain rights of a "coastal State".

Mauritius further contends that the MPA is fundamentally incompatible with the rights and obligations provided for by the Convention, including the fishing rights of Mauritius in regard to the Chagos Archipelago and its surrounding waters. Mauritius alleges that the United Kingdom has also breached its obligations under the Convention and international law with respect to consultation and co-operation.

In its final submissions, Mauritius also contends that it was entitled to file Preliminary Information regarding the continental shelf surrounding the Chagos Archipelago with the United Nations Commission on the Limits of the Continental Shelf ("CLCS") and that the United Kingdom should not be permitted to prevent the CLCS from making recommendations in respect of any further submissions that Mauritius may make regarding the Chagos Archipelago.

In bringing these proceedings Mauritius has invoked Articles 286 and 287 of the Convention.

The United Kingdom challenges the Tribunal’s jurisdiction over all aspects of the dispute. The United Kingdom first raised this challenge in its Preliminary Objections and at a hearing before the Tribunal on 11 January 2013 regarding the procedure to consider jurisdictional objections. By Order of 15 January 2013, the Tribunal rejected the United Kingdom’s request for a separate procedural phase and decided that jurisdictional objections would be considered together with the proceedings on the merits.

According to the United Kingdom, these proceedings are an attempt by Mauritius to construct a case under the Convention in order to bring a dispute concerning sovereignty over the Chagos Archipelago within the jurisdiction of the Tribunal, which is "artificial and baseless."¹ Furthermore, the United Kingdom contends that Mauritius has failed to meet its obligation to consult with the United Kingdom concerning the violations of the Convention of which Mauritius complains.

With respect to the merits of Mauritius’ claims, the United Kingdom asserts that it acquired sovereignty over the Chagos Archipelago in 1814, continued to exercise sovereignty at all relevant times, and is therefore unquestionably the coastal State for the purposes of the Convention. The United Kingdom also denies that the MPA is incompatible with the rights of Mauritius under the Convention. Finally, the United Kingdom contends that it has complied fully with its obligations under the Convention and international law to consult and co-operate.

By its Notification and Statement of Claim dated 20 December 2010, Mauritius initiated arbitration proceedings against the United Kingdom pursuant to Article 287 of the Convention and in accordance with Article 1 of Annex VII to the Convention.

In its Notification and Statement of Claim, Mauritius appointed Judge Rüdiger Wolfrum, a German national, as a member of the Tribunal in accordance with Article 3(b) of Annex VII to the Convention. On 19 January 2011, the United Kingdom appointed Judge Sir Christopher Greenwood CMG, QC, a British national, as a member of the Tribunal in accordance with Article 3(c) of Annex VII to the Convention.

Owing to disagreement between the Parties regarding the appointment of the remaining three members of the Tribunal, Mauritius sent a letter dated 21 February 2011 to the President of the International Tribunal for the Law of the Sea ("ITLOS"). Therein, Mauritius requested that the President of ITLOS appoint the remaining three members of the Tribunal in accordance with Article 3(e) of Annex VII to the Convention.

On 25 March 2011, the President of ITLOS appointed Judge James Kateka, a Tanzanian national, and Judge Albert Hoffmann, a South African national, as arbitrators, and Professor Ivan Shearer AM, an Australian national, as arbitrator and President of the Tribunal.

On 31 March 2011, the President of the Tribunal wrote to the Permanent Court of Arbitration (the "PCA") to ascertain whether the PCA was willing to serve as Registry for the proceedings. The PCA responded affirmatively by letter of the same date. By communications dated 4 and 6 April 2011, respectively, the United Kingdom and Mauritius confirmed that they had no objection to the PCA serving as Registry for the proceedings. The PCA’s appointment was subsequently formalized on 21 March 2012 by the conclusion of Terms of Appointment.

On 2 May 2011, the PCA transmitted to the Parties the Declarations of Acceptance and Statements of Impartiality and Independence of the five arbitrators. An additional Disclosure Statement submitted by Judge Greenwood was also transmitted under the same cover.

On 19 May 2011, Mauritius requested further disclosure from Judge Greenwood concerning his relationship with the Government of the United Kingdom. Judge Greenwood provided a Further Disclosure Statement on 20 May 2011, in which he reiterated his independence and commitment to act with complete impartiality.

On 23 May 2011, Mauritius conveyed its intention to challenge the appointment of Judge Greenwood. On 30 May 2011, the Tribunal communicated to the Parties a proposed procedure and timetable for resolving the challenge to Judge Greenwood, in which the remaining members of the Tribunal would decide the challenge. The United Kingdom and Mauritius indicated their consent to this approach on 3 and 8 June 2011, respectively.

Between June and August 2011, Mauritius and the United Kingdom made submissions in respect of the challenge, in accordance with the agreed procedure.

On 4 October 2011, the Tribunal held a hearing on the challenge at the Peace Palace in The Hague, the Netherlands. On 13 October 2011, the Tribunal issued its decision (without reasons) to dismiss the challenge to the appointment of Judge Greenwood. The Tribunal subsequently provided written reasons in respect of its decision on 30 November 2011.

On 6 January 2012, the Tribunal circulated draft Terms of Appointment for the proceedings and invited the Parties’ comments. The Tribunal also invited the Parties to seek agreement on the procedural rules and on a schedule for the further conduct of the proceedings.

Following an exchange of correspondence, the Parties and the Tribunal reached agreement on the Terms of Appointment, which were finalized and signed on 21 March 2012.

Between January and March 2012, the Parties and the Tribunal exchanged correspondence concerning the draft Rules of Procedure, in particular with respect to the hearing venue and the procedure in the event of a request to consider objections to the Tribunal’s jurisdiction in a preliminary procedural phase. Following consultation with the Parties, the Tribunal finalized and adopted the Rules of Procedure on 29 March 2012.

On 13 December 2012, following consultation with the Parties, the Tribunal issued Procedural Order N° 1, specifying in greater detail the procedure to be followed with respect to submissions.

On 1 August 2012, Mauritius submitted its Memorial.

On 31 October 2012, the United Kingdom submitted its Preliminary Objections to Jurisdiction, in which it requested, among other things, the bifurcation of proceedings to address its jurisdictional objections as a preliminary matter and a separate hearing on the question of bifurcation. On 21 November 2012, Mauritius submitted its Written Observations on the Question of Bifurcation, in which it opposed the bifurcation of the proceedings.

On 21 December 2012, the United Kingdom submitted a Written Reply of the United Kingdom to the Written Observations of Mauritius on the question of bifurcation.

On 11 January 2013, the Tribunal held a hearing on the question of bifurcation in Dubai, United Arab Emirates. On 15 January 2013, following the hearing, the Tribunal issued Procedural Order N° 2, in which it rejected the United Kingdom’s request for bifurcation and decided that jurisdictional objections would be considered with the proceedings on the merits.

On 17 January 2013, the United Kingdom requested an extension of time for the submission of its Counter-Memorial. The Parties subsequently agreed to an amended schedule for written submissions, which was conveyed to the Tribunal by a letter dated 30 January 2013. In accordance with this amended schedule, the United Kingdom submitted its Counter-Memorial on 15 July 2013.

On 15 November 2013, Mauritius requested an extension of time until 18 November 2013 to file its Reply. The Tribunal granted this request on 16 November 2013 on the basis that an equivalent extension was granted to the United Kingdom with respect to the filing of its Rejoinder. Mauritius submitted its Reply on 18 November 2013.

On 17 March 2014, the United Kingdom submitted its Rejoinder.

In its Reply, Mauritius noted that certain documents set out in Annex 185 thereto contained redactions. These documents had originally been disclosed by the United Kingdom in the course of separate judicial proceedings in the English courts to which Mauritius was not a party. Mauritius invited the United Kingdom to confirm that it would "submit, along with its Rejoinder, unredacted copies of the documents at Annex 185" and reserved its right to make an application to the Tribunal in this respect.²

On 30 November 2013, the United Kingdom responded to Mauritius’ invitation and indicated that it would revert in due course regarding the appropriateness of additional disclosure. The United Kingdom confirmed, in any event, that no redactions had been made for the purpose of suppressing evidence which might be unhelpful to it in these proceedings. The United Kingdom further asserted that it had "fully complied with international law practices and the applicable Rules of Procedure" in its production of documents.

On 13 December 2013, Mauritius invited the United Kingdom to confirm the basis on which it had made redactions to the documents in Annex 185 to Mauritius’ Reply and whether it maintained any or all of those redactions in the present proceedings. On 19 December 2013, the United Kingdom repeated the contents of its letter of 30 November 2013 and stated that it would consider the extent to which any redactions could be removed in the course of drafting its Rejoinder.

On 9 January 2014, the Tribunal wrote to the Parties, recalling the Parties’ correspondence and urging the United Kingdom to remove "all redactions that are not strictly required on grounds of irrelevancy or legal professional privilege" and to indicate the basis for each redaction that it wished to maintain.

On 11 February 2014, Mauritius wrote to the Tribunal, requesting an indication from the United Kingdom regarding the status of its review of the redacted documents. In response, on 14 February 2014, the United Kingdom noted that "there are a large number of redactions to be considered, and the process needs to be carried out in consultation with the counsel who represented the Government in the proceedings in the United Kingdom courts" and indicated that it would revert as soon as possible. On 19 February 2014, the Tribunal requested the United Kingdom to complete its review of all of the redacted documents by 3 March 2014.

On 3 March 2014, the United Kingdom provided a version of the documents contained in Annex 185 with some redactions removed, while maintaining a number of redactions "principally on the grounds of legal professional privilege, relationships with third countries and national security." By the same letter, the United Kingdom requested Mauritius to confirm that it had conducted a review of its own internal documents and that all relevant documents had been disclosed.

On 14 March 2014, Mauritius invited the United Kingdom to indicate the basis for each remaining redaction, recalling the Tribunal’s letter of 9 January 2014. Mauritius also confirmed, with respect to the United Kingdom’s request, that "Mauritius considers that it has fully pleaded its case, including by way of disclosure of appropriate documentation."

On 18 March 2014, the Tribunal confirmed its intention for the United Kingdom to indicate the basis for each redaction it sought to maintain and requested that the United Kingdom comment on Mauritius’ proposal for the Tribunal or a document master to review the unredacted texts and confirm in each instance that non-disclosure was justified. By the same letter, the Tribunal requested that Mauritius respond to the United Kingdom concerning the disclosure of its own internal documents.

On 25 March 2014, the United Kingdom submitted a version of the documents contained in Annex 185 with the grounds of each redaction indicated and noted that it was willing to accommodate discussions with the Tribunal on an ex parte basis regarding the rationale for any particular redaction.

On 7 April 2014, Mauritius set out its concerns regarding the United Kingdom’s stated grounds for the remaining redactions and invited the Tribunal to request the United Kingdom to provide unredacted copies of the documents for ex parte review to ensure that the redactions were justified. With respect to Mauritius’ internal documents, Mauritius noted that no order for document production had been sought, but indicated that, in any case, it had reviewed its own internal documents to the fullest extent possible and disclosed all relevant documents.

On 8 April 2014, the Tribunal requested the United Kingdom to make available unredacted copies of the documents in Annex 185 for examination by the Tribunal in Istanbul in advance of the hearing. By letter dated 9 April 2014, the United Kingdom confirmed its arrangements to transport the documents to Istanbul and invited the Tribunal to attend at the British Consulate-General in Istanbul on 21 April 2014.

On 14 April 2014, the Tribunal proposed a procedure in respect of the redacted documents, providing for a preliminary review by the Presiding Arbitrator of unredacted copies of the documents themselves, followed by a review by the Tribunal as a whole, "unless considered unnecessary in light of the Presiding Arbitrator’s preliminary review."

On 20 April 2014, following a further exchange of correspondence with the Parties, the President informed the Parties that he would attend an ex parte meeting at the British Consulate-General on 21 April 2014 and that this meeting would be "limited to confirming that the contents of each redaction qualify for non-disclosure on grounds recognized by the Tribunal."

On 21 April 2014, the President of the Tribunal, together with the Registrar, attended the ex parte meeting at the British Consulate-General in Istanbul. Thereafter, the President reported his findings to the Tribunal as a whole.

On 22 April 2014, the Tribunal wrote to the Parties, confirming the President’s finding that each redaction was justified and conveying the Tribunal’s decision that the redacted passages should not be subject to disclosure.

On 22 November 2013, the Tribunal, following consultations with the Parties and the PCA, confirmed that the hearing would take place in Istanbul, Turkey.

On 22 April 2014, the Tribunal, with the Parties’ consent, confirmed the change in the place of the hearing by a formal amendment to Article 9(2) of the Rules of Procedure.

The hearing on jurisdiction and the merits took place from 22 April to 9 May 2014 at the facilities of the Pera Palace Hotel, Istanbul, Turkey. The following individuals participated on behalf of the Parties:

Mauritius United Kingdom

Agent Agent

Mr Dheerendra Kumar Dabee GOSK, SC Mr Christopher Whomersley CMG

Deputy Agent Deputy Agent

Ms Aruna Devi Narain Ms Margaret Purdasy

Counsel Counsel

Professor James Crawford AC, SC, FBA The Rt. Hon. Dominic Grieve QC, MP

Professor Philippe Sands QC Professor Alan Boyle

Ms Alison MacDonald Ms Penelope Nevill

Mr Paul S. Reichler Ms Amy Sander

Mr Andrew Loewenstein Sir Michael Wood KCMG

Mr Samuel Wordsworth QC

Representatives

Mr Suresh Chandre Seeballuck GOSK Junior Counsel HE Dr Jaya Nyamrajsigh Meetarbhan GOSK Mr Eran Sthoeger

Ms Shiu Ching Young Kim Fat

Representatives

Advisers Ms Jo Bowyer

Ms Elizabeth Wilmshurst CMG Ms Mina Patel

Dr Douglas Guilfoyle Ms Neelam Rattan

Ms Rebecca Raynsford Mr Douglas Wilson

Junior Counsel Mr Yuri Parkhomenko Mr Remi Reichhold

Mr Fernando L. Bordin Assistants

Mr Rodrigo Tranamil Ms Nancy Lopez

On 16 May 2014, the PCA issued a press release on the conclusion of the hearing on jurisdiction and the merits.

Mauritius is composed of a group of islands,³ situated in the south-western part of the Indian Ocean.⁴ In addition to one main island, the Island of Mauritius, the territory of Mauritius includes the islands of Cargados Carojos Shoals (the St Brandon Group of 16 Islands and Islets);⁵ Rodrigues Island; and Agalega.⁶ Pursuant to Section 111 of its Constitution (as amended with effect from 1992), Mauritius also claims the territory of Tromelin Island (disputed by the French Republic) and the Chagos Archipelago (disputed by the United Kingdom).⁷ The location of Mauritius and the Chagos Archipelago is shown in Map 1 on page 15.

The Chagos Archipelago comprises a number of coral atolls,⁸ located in the middle of the Indian Ocean, some of which are above sea level and form islands.⁹ The largest island of the Chagos Archipelago, Diego Garcia, is situated in the south-west of the archipelago.¹⁰ The Chagos Archipelago is shown in Map 2 on page 17.

Beginning in the late 15th century, Portuguese explorers began to venture into the Indian Ocean and recorded the location of Mauritius and the other Mascarene Islands, Rodrigues and Réunion (the latter presently a French overseas department). In the 16th century, the Portuguese were joined by Dutch and English sailors, both nations having established East India Companies to exploit the commercial opportunities of the Indian Ocean and the Far East. Although Mauritius was used as a stopping point in the long voyages to and from the Indian Ocean, no attempt was made to establish a permanent settlement.¹¹

The first permanent colony in Mauritius was established by the Dutch East India Company in 1638.¹² The Dutch maintained a small presence on Mauritius, with a brief interruption, until 1710 at which point the Dutch East India Company abandoned the island.¹³ Following the Dutch departure, the French government took possession of Mauritius in 1715, renaming it the Ile de France.¹⁴

The Chagos Archipelago was known during this period, appearing on Portuguese charts as early as 1538, but remained largely untouched.¹⁵ France progressively claimed and surveyed the Archipelago in the mid-18th century and granted concessions for the establishment of coconut plantations, leading to permanent settlement. Throughout this period, France administered the Chagos Archipelago as a dependency of the Ile de France.¹⁶

In 1810, the British captured the Ile de France¹⁷ and renamed it Mauritius.¹⁸ By the Treaty of Paris of 30 May 1814, France ceded the Ile de France and all its dependencies (including the Chagos Archipelago) to the United Kingdom.¹⁹

These early historical events are not in dispute between the Parties.²⁰

From the date of the cession by France until 8 November 1965, when the Chagos Archipelago was detached from the colony of Mauritius, the Archipelago was administered by the United Kingdom as a Dependency of Mauritius.²¹ During this period, the economy of the Chagos Archipelago was primarily driven by the coconut plantations and the export of copra (dried coconut flesh) for the production of oil, although other activities developed as the population of the Archipelago expanded.²² British administration over the Chagos Archipelago was exercised by various means, including by visits to the Chagos Archipelago made by Special Commissioners and Magistrates from Mauritius.²³

Although the broad outlines of British Administration of the colony during this period are not in dispute, the Parties disagree as to the extent of economic activity in the Chagos Archipelago and its significance for Mauritius, and on the significance of the Archipelago’s status as a dependency.²⁴ Mauritius contends that there were "close economic, cultural and social links between Mauritius and the Chagos Archipelago"²⁵ and that "the administration of the Chagos Archipelago as a constituent part of Mauritius continued without interruption throughout that period of British rule".²⁶ The United Kingdom, in contrast, submits that the Chagos Archipelago was only "very loosely administered from Mauritius"²⁷ and "in law and in fact quite distinct from the Island of Mauritius."²⁸ The United Kingdom further contends that "[t]he islands had no economic relevance to Mauritius, other than as a supplier of coconut oil"²⁹ and that, in any event, economic, social and cultural ties between the Chagos Archipelago and Mauritius during this period are irrelevant to the Archipelago’s legal status.³⁰

Beginning in 1831, the administration of the British Governor of Mauritius was supplemented by the introduction of a Council of Government, originally composed of ex-officio members and members nominated by the Governor.³¹ The composition of this Council was subsequently democratized through the progressive introduction of elected members.³² In 1947, the adoption of a new Constitution for Mauritius replaced the Council of Government with separate Legislative and Executive Councils.³³ The Legislative Council was composed of the Governor as President, 19 elected members, 12 members nominated by the Governor and 3 ex-officio members.³⁴

The first election of the Legislative Council took place in 1948, and the Mauritius Labour Party (the "MLP") secured 12 of the 19 seats available for elected members.³⁵ The MLP strengthened its position in the 1953 election by securing 14 of the available seats, although the MLP lacked an overall majority in the Legislative Council because of the presence of a number of members appointed by the Governor.³⁶

The 1953 election marked the beginning of Mauritius’ move towards independence.³⁷ Following that election, Mauritian representatives began to press the British Government for universal suffrage, a ministerial system of government and greater elected representation in the Legislative Council. By 1959, the MLP-led government had openly adopted the goal of complete independence.

Constitutional Conferences were held in 1955, 1958, 1961, and 1965,³⁸ resulting in a new constitution in 1958 and the creation of the post of Chief Minister in 1961 (renamed as the Premier after 1963).³⁹ In 1962, Dr Seewoosagur Ramgoolam (later Sir Seewoosagur Ramgoolam) became the Chief Minister⁴⁰ within a Council of Ministers chaired by the Governor and, following the 1963 election, formed an all-party coalition government to pursue negotiations with the British on independence.⁴¹

The final Constitutional Conference was held in London in September 1965 and was principally concerned with the debate between those Mauritian political leaders favouring independence and those preferring some form of continued association with the United Kingdom.⁴² On 24 September 1965, the final day of the conference, the Secretary of State for the Colonies, the Rt. Hon. Anthony Greenwood MP,⁴³ who was the minister in the United Kingdom Government with responsibility for Mauritius, announced that the United Kingdom Government intended that Mauritius would proceed to full independence.⁴⁴

Mauritius became independent on 12 March 1968.⁴⁵

In conjunction with the move toward Mauritian independence, the United Kingdom formulated a proposal to separate the Chagos Archipelago from the remainder of the colony of Mauritius, and to retain the Archipelago under British control. According to Mauritius, the proposal to separate the Chagos Archipelago stemmed from a decision by the United Kingdom in the early 1960s to "accommodate the United States’ desire to use certain islands in the Indian Ocean for defence purposes."⁴⁶

The record before the Tribunal sets out a series of bilateral talks between the United Kingdom and the United States in 1964 at which the two States decided that, in order to execute the plans for a defence facility in the Chagos Archipelago, the United Kingdom would "provide the land, and security of tenure, by detaching islands and placing them under direct U.K. administration."⁴⁷

The suitability of Diego Garcia as the site of the planned defence facility was determined following a joint survey of the Chagos Archipelago and certain islands of the Seychelles in 1964.⁴⁸ Following the survey, the United States sent its proposals to the United Kingdom, identifying Diego Garcia as its first preference as the site for the defence facility.⁴⁹ The United Kingdom and the United States conducted further negotiations between 1964 and 1965 regarding the desirability of "detachment of the entire Chagos Archipelago,"⁵⁰ as well as the islands of Aldabra, Farquhar and Desroches (then part of the colony of the Seychelles).⁵¹ They further discussed the terms of compensation that would be required "to secure the acceptance of the proposals by the local Governments."⁵²

On 19 July 1965, the Governor of Mauritius was instructed to communicate the proposal to detach the Chagos Archipelago to the Mauritius Council of Ministers and to report back on the Council’s reaction.⁵³ The initial reaction of the Mauritian Ministers, conveyed by the Governor’s report of 23 July 1965, was a request for more time to consider the proposal. The report also noted that Sir Seewoosagur Ramgoolam expressed "dislike of detachment".⁵⁴ At the next meeting of the Council on 30 July 1965, the Mauritian Ministers indicated that detachment would be "unacceptable to public opinion in Mauritius" and proposed the alternative of a longterm lease, coupled with safeguards for mineral rights and a preference for Mauritius if fishing or agricultural rights were ever granted.⁵⁵ The Parties differ in their understanding of the strength of, and motivation for, the Mauritian reaction.⁵⁶ In any event, on 13 August 1965, the Governor of Mauritius informed the Mauritian Ministers that the United States objected to the proposal of a lease.⁵⁷

Discussions over the detachment of the Chagos Archipelago continued in a series of meetings between certain Mauritian political leaders, including Sir Seewoosagur Ramgoolam,⁵⁸ and the Secretary of State for the Colonies, Anthony Greenwood, coinciding with the Constitutional Conference of September 1965 in London.⁵⁹ Over the course of three meetings, the Mauritian leaders pressed the United Kingdom with respect to the compensation offered for Mauritian agreement to the detachment of the Archipelago, noting the involvement of the United States in the establishment of the defence facility and Mauritius’ need for continuing economic support (for example through a higher quota for Mauritius sugar imports into the United States), rather than the lump sum compensation being proposed by the United Kingdom.⁶⁰ The United Kingdom took the firm position that obtaining concessions from the United States was not feasible; the United Kingdom did, however, increase the level of lump sum compensation on offer from £1 million to £3 million and introduced the prospect of a commitment that the Archipelago would be returned to Mauritius when no longer needed for defence purposes.⁶¹ The Mauritian leaders also met with the Economic Minister at the U.S. Embassy in London on the question of sugar quotas,⁶² and Sir Seewoosagur Ramgoolam met privately with Prime Minister Harold Wilson on the morning of 23 September 1965.⁶³ The United Kingdom’s record of this conversation records Prime Minister Wilson having told Sir Seewoosagur Ramgoolam that -

in theory, there were a number of possibilities. The Premier and his colleagues could return to Mauritius either with Independence or without it. On the Defence point, Diego Garcia could either be detached by order in Council or with the agreement of the Premier and his colleagues. The best solution of all might be Independence and detachment by agreement, although he could not of course commit the Colonial Secretary at this point.⁶⁴

The meetings culminated in the afternoon of 23 September 1965 (the "Lancaster House Meeting") in a provisional agreement on the part of Sir Seewoosagur Ramgoolam and his colleagues⁶⁵ to agree in principle to the detachment of the Archipelago in exchange for the Secretary of State recommending certain actions by the United Kingdom to the Cabinet.⁶⁶ The draft record of the Lancaster House Meeting set out the following:

Summing up the discussion, the SECRETARY OF STATE asked whether he could inform his colleagues that Dr. [Seewoosagur] Ramgoolam, Mr. Bissoondoyal and Mr. Mohamed were prepared to agree to the detachment of the Chagos Archipelago on the understanding that he would recommend to his colleagues the following:-

(i) negotiations for a defence agreement between Britain and Mauritius;

(ii) in the event of independence an understanding between the two governments that they would consult together in the event of a difficult internal security situation arising in Mauritius;

(iii) compensation totalling up to [illegible] Mauritius Government over and above direct compensation to landowners and the cost of resettling others affected in the Chagos Islands;

(iv) the British Government should use its good offices with the United States Government in support of Mauritius’ request for concessions over sugar imports and the supply of wheat and other commodities;

(v) that the British Government would do their best to persuade the American Government to use labour and materials from Mauritius for construction work in the islands;

(vi) that if the need for the facilities on the islands disappeared the islands should be returned to Mauritius.

SIR S. RAMGOOLAM said that this was acceptable to him and Messrs. Bissoondoyal and Mohamed in principle but he expressed the wish to discuss it with his other ministerial colleagues.

Thereafter, Sir Seewoosagur Ramgoolam addressed a handwritten note to the Under-Secretary of State at the Colonial Office, Mr Trafford Smith, setting out further conditions relating to navigational and meteorological facilities on the Archipelago, fishing rights, emergency landing facilities, and the benefit of mineral or oil discoveries. Sir Seewoosagur Ramgoolam’s note provided as follows:

Dear Mr. Trafford Smith,

I and Mr Mohamed have gone through the enclosed paper on the question of Diego Garcia and another near island (i.e. two altogether) and we wish to point out the amendments that should be effected on page 4 of this document. The matters to be added formed part of the original requirements submitted to H.M.G. We think that these can be incorporated in any final agreement.

With kind regards,

S. Ramgoolam

P.S. The two copies handed over to me are herewith enclosed.⁶⁷

The third page to Sir Seewoosagur Ramgoolam’s note set out the following items:

(vii) Navigational & Meteorological facilities

(viii) Fishing rights

(ix) Use of Air Strip for Emergency Landing and if required for development of the other islands

(x) Any mineral or oil discovered on or near islands to revert to the Mauritius Government.⁶⁸

These additions were incorporated into paragraph 22 of the final record of the Lancaster House Meeting, which the Tribunal considers to warrant quotation in full:

RECORD OF A MEETING HELD IN LANCASTER HOUSE AT 2. 30 P.M. ON THURSDAY 23rd SEPTEMBER

MAURITIUS DEFENCE MATTERS

Present:- The Secretary of State

(in the Chair)

Lord Taylor

Sir S. Ramgoolam

Sir Hilton Poynton

Mr. S. Bissoondoyal

Sir John Rennie

Mr. J. M. Paturau

Mr. P. R. Noakes

Mr. A. R. Mohamed

Mr. J. Stacpoole

THE SECRETARY OF STATE expressed his apologies for the unavoidable postponements and delays which some delegations at the Constitutional Conference had met with earlier in the day. He explained that he was required to inform his colleagues of the outcome of his talks with Mauritian Ministers about the detachment of the Chagos Archipelago at 4 p.m. that afternoon and was therefore anxious that a decision should be reached at the present meeting.

2. He expressed his anxiety that Mauritius should agree to the establishment of the proposed facilities, which besides their usefulness for the defence of the free world, would be valuable to Mauritius itself by ensuring a British presence in the area. On the other hand it appeared that the Chagos site was not indispensable and there was therefore a risk that Mauritius might lose this opportunity. In the previous discussions he had found himself caught between two fires: the demands which the Mauritius Government had made, mainly for economic concessions by the United States, and the evidence that the United States was unable to concede these demands. He had throughout done his best to ensure that whatever arrangements were agreed upon should secure the maximum benefit for Mauritius. He was prepared to recommend to his colleagues if Mauritius agreed to the detachment of the Chagos Archipelago:-

(i) negotiations for a defence agreement between Britain and Mauritius;

(ii) that if Mauritius became independent, there should be an understanding that the two governments would consult together in the event of a difficult internal security situation arising in Mauritius;

(iii) that the British Government should use its good offices with the United States Government in support of Mauritius request for concessions over the supply of wheat and other commodities

(iv) that compensation totalling up to £3m. should be paid to the Mauritius Government over and above direct compensation to landowners and others affected in the Chagos Islands.

This was the furthest the British Government could go. They were anxious to settle this matter by agreement but the other British Ministers concerned were of course aware that the islands were distant from Mauritius, that the link with Mauritius was an accidental one and that it would be possible for the British Government to detach them from Mauritius by Order in Council.

3. SIR S. RAMGOOLAM replied that the Mauritius Government were anxious to help and to play their part in guaranteeing the defence of the free world. He asked whether the Archipelago could not be leased, (THE SECRETARY OF STATE said that this was not acceptable). MR. BISSOONDOYAL enquired whether the Islands would revert to Mauritius if the need for defence facilities there disappeared. THE SECRETARY OF STATE said that he was prepared to recommend this to his colleagues.

4. MR. PATURAU said that he recognised the value and importance of an Anglo-Mauritius defence agreement, and the advantage for Mauritius if the facilities were established in the Chagos Islands, but he considered the proposed concessions a poor bargain for Mauritius.

5. MR. BISSOONDOYAL asked whether there could be an assurance that supplies and manpower from Mauritius would be used so far as possible. THE SECRETARY OF STATE said that the United States Government would be responsible for construction work and their normal practice was to use American manpower but he felt sure the British Government would do their best to persuade the American Government to use labour and materials from Mauritius.

6. SIR S. RAMGOOLAM asked the reason for Mr. Koenig’s absence from the meeting and MR. BISSOONDOYAL asked whether the reason was a political one, saying that if so this might affect the position.

7. Mr. MOHAMED made an energetic protest against repeated postponements of the Secretary of State’s proposed meeting with the M.C.A. [Muslim Committee of Action], which he regarded as a slight to his party.

8. THE SECRETARY OF STATE repeated the apology with which he had opened the meeting, explaining that it was often necessary in such conferences to concentrate attention on a delegation which was experiencing acute difficulties, while he himself had been obliged to devote much time to a crisis in another part of the world.

9. MR MOHAMED then handed the Secretary of State a recent private letter from Mauritius which disclosed that extensive misrepresentations about the course of the Conference had been published in a Parti Mauricien newspaper. THE SECRETARY OF STATE commented that such misrepresentations should be disregarded, and that MR. MOHAMED had put forward the case for his community with great skill and patience.

10. MR. MOHAMED said that his party was ready to leave the bases question to the discretion of H.M.G. and to accept anything which was for the good of Mauritius. Mauritius needed a guarantee that defence help would be available nearby in case of need.

11. At SIR S. RAMGOOLAM’s request the Secretary of State repeated the outline he had given at a previous meeting of the development aid which would be available to Mauritius between 1966-1968, viz. a C.D. & W. [Commonwealth Development & Welfare] allocation totalling £2.4 million (including carryover) thus meaning that £800,000 a year would be available by way of grants in addition Mauritius would have access to Exchequer loans, which might be expected to be of the order of £1m. a year, on the conditions previously explained. He pointed out that Diego Garcia was not an economic asset to Mauritius and that the proposed compensation of £3m. would be an important contribution to Mauritius development. There was no chance of raising this figure.

12. SIR S. RAMGOOLAM said that there was a gap of some £4m. per year between the development expenditure which his government considered necessary in order to enable the Mauritian economy to "take off" and the resources in sight, and enquired whether it was possible to provide them with additional assistance over a 10 year period to bridge this gap.

13. THE SECRETARY OF STATE mentioned the possibility of arranging for say £2m. of the proposed compensation to be paid in 10 instalments annually of £200,000.

14. SIR S. RAMGOOLAM enquired about the economic settlement with Malta on independence and was informed that these arrangements had been negotiated in the context of a special situation for which there was no parallel in Mauritius.

15. SIR H. POYNTON pointed out that if Mauritius did not become independent within three years, the Colonial Office would normally consider making a supplementary allocation of C.D. & W. grant money to cover the remainder of the life of the current C.D. & W. Act, i.e. the period up to 1970. He added that if Mauritius became independent, they would normally receive the unspent balance of their C.D. & W. allocation in a different form and it would be open to them after the three year period to seek further assistance such as Britain was providing for a number of independent Commonwealth countries.

16. SIR S. RAMGOOLAM said that he was prepared to agree in principle to be helpful over the proposals which H.M.G. had put forward but he remained concerned about the availability of capital for development in Mauritius and hoped that the British Government would be able to help him in this respect.

17. MR. BISSOONDOYAL said that while it would have been easier to reach conclusions if it had been possible to obtain unanimity among the party leaders, his party was prepared to support the stand which the Premier was taking. They attached great importance to British assistance being available in the event of a serious emergency in Mauritius.

18. MR. PATURAU asked that his disagreement should be noted. The sum offered as compensation was too small and would provide only temporary help for Mauritius economic needs. Sums as large as £25m. had been mentioned in the British press and Mauritius needed a substantial contribution to close the gap of £4-5m. in the development budget. He added that since the decision was not unamimous [ sic ], he foresaw serious political trouble over it in Mauritius.

19. THE SECRETARY OF STATE referred to his earlier suggestion that payment of the monetary compensation should be spread over a period of years.

20. SIR S. RAMGOOLAM said that he was hoping to come to London for economic discussions in October. The Mauritius Government’s proposals for development expenditure had not yet been finalised, but it was already clear that there would be a very substantial gap on the revenue side.

21. SIR H. POYNTON said that the total sum available for C.D. & W. assistance to the dependent territories was a fixed one and it would not be possible to increase the allocation for one territory without proportionately reducing that of another.

22. Summing up the discussion, the SECRETARY OF STATE asked whether he could inform his colleagues that Dr. [Sir Seewoosagur] Ramgoolam, Mr. Bissoondoyal and Mr. Mohamed were prepared to agree to the detachment of the Chagos Archipelago on the understanding that he would recommend to his colleagues the following:-

(i) negotiations for a defence agreement between Britain and Mauritius;

(ii) in the event of independence an understanding between the two governments that they would consult together in the event of a difficult internal security situation arising in Mauritius;

(iii) compensation totalling up to £3m. should be paid to the Mauritius Government over and above direct compensation to landowners and the cost of resettling others affected in the Chagos Islands;

(iv) the British Government would use their good offices with the United States Government in support of Mauritius’ request for concessions over sugar imports and the supply of wheat and other commodities;

(v) that the British Government would do their best to persuade the American Government to use labour and materials from Mauritius for construction work in the islands;

(vi) the British Government would use their good offices with the U.S. Government to ensure that the following facilities in the Chagos Archipelago would remain available to the Mauritius Government as far as practicable:

(a) Navigational and Meteorological facilities;

(b) Fishing Rights;

(c) Use of Air Strip for emergency landing and for refuelling civil planes without disembarkation of passengers.

(vii) that if the need for the facilities on the islands disappeared the islands should be returned to Mauritius;

(viii) that the benefit of any minerals or oil discovered in or near the Chagos Archipelago should revert to the Mauritius Government.

23. SIR S. RAMGOOLAM said that this was acceptable to him and Messrs. Bissoondoyal and Mohamed in principle but he expressed the wish to discuss it with his other ministerial colleagues.

24. THE SECRETARY OF STATE pointed out that he had to leave almost immediately to convey the decision to his own colleagues and LORD TAYLOR urged the Mauritian Ministers not to risk losing the substantial sum offered and the important assurance of a friendly military presence nearby.

25. SIR S. RAMGOOLAM said that Mr. Paturau had urged him to make a further effort to secure a larger sum by way of compensation, but the Secretary of State said there was no hope of this.

26. SIR J. RENNIE said that while he had hoped that Mauritius would be able to obtain trading concessions in these negotiations, this was now ruled out. It was in the interest of Mauritius to take the opportunity offered to ensure a friendly military presence in the area. What was important about the compensation was the use to which the lump sum was put.

27. SIR S. RAMGOOLAM mentioned particular development projects, such as a dam and a land settlement scheme, and expressed the hope that Britain would make additional help available in an independence settlement.

28. SIR H. POYNTON said that the Mauritius Government should not lose sight of the possibility of securing aid for such purposes from the World Bank, the I.D.A. and from friendly governments. While Mauritius remained a colony such powers as Western Germany regarded Mauritius economic problems as a British responsibility but there was the hope that after independence aid would be available from these sources. When Sir S. Ramgoolam suggested that he had said that grants could be extended for up to 10 years, Sir H. Poynton pointed out that he had only indicated that when the period for which the next allocation had been made expired, it would be open to the Mauritius Government to seek further assistance, from Britain, even though Mauritius had meanwhile become independent. It would not be possible to reach any understanding at present beyond saying that independence did not preclude the possibility of negotiating an extension of Commonwealth aid.

29. At this point the SECRETARY OF STATE left for 10, Dowing Street [ sic ], after receiving authority from Sir S. Ramgoolam and Mr. Bissoondoyal to report their acceptance in principle of the proposals outlined above subject to the subsequent negotiation of details. Mr. Mohamed gave the same assurance, saying that he spoke also for his colleague Mr. Osman. Mr. Paturau said he was unable to concur.⁶⁹

Collectively, the Tribunal will refer to points (i) through (viii) of paragraph 22 of the record of this meeting as the "Lancaster House Undertakings".

On 6 October 1965, instructions were sent to the Governor of Mauritius to secure "early confirmation that the Mauritius Government is willing to agree that Britain should now take the necessary legal steps to detach the Chagos Archipelago from Mauritius on the conditions enumerated in (i)-(viii) in paragraph 22 of the enclosed record [of the Lancaster House Meeting]."⁷⁰ The Secretary of State went on to note that -

5. As regards points (iv), (v) and (vi) the British Government will make appropriate representation to the American Government as soon as possible. You will be kept fully informed of the progress of these representations.

6. The Chagos Archipelago will remain under British sovereignty, and Her Majesty’s Government have taken careful note of points (vii) and (viii).⁷¹

On 5 November 1965, the Governor of Mauritius informed the Colonial Office as follows:

Council of Ministers today confirmed agreement to the detachment of Chagos Archipelago on conditions enumerated, on the understanding that

(1) statement in paragraph 6 of your despatch "H.M.G. have taken careful note of points (vii) and (viii)" means H.M.G. have in fact agreed to them.

(2) As regards (vii) undertaking to Legislative Assembly excludes

(a) sale or transfer by H.M.G. to third party or

(b) any payment or financial obligation by Mauritius as condition of return.

(3) In (viii) "on or near" means within area within which Mauritius would be able to derive benefit but for change of sovereignty. I should be grateful if you would confirm this understanding is agreed.⁷²

The Governor also noted that "[Parti Mauricien Social Démocrate] Ministers dissented and (are now) considering their position in the government."⁷³ The Parties differ regarding the extent to which Mauritian consent to the detachment was given voluntarily.⁷⁴

The detachment of the Chagos Archipelago was effected by the establishment of the BIOT on 8 November 1965 by Order in Council.⁷⁵ Pursuant to the Order in Council, the governance of the newly created BIOT was made the responsibility of the office of the BIOT Commissioner, appointed by the Queen upon the advice of the United Kingdom FCO. The BIOT Commissioner is assisted in the day-to-day management of the territory by a BIOT Administrator.

On the same day, the Secretary of State cabled the Governor of Mauritius as follows:

As already stated in paragraph 6 of my despatch No. 423, the Chagos Archipelago will remain under British sovereignty. The islands are required for defence facilities and there is no intention of permitting prospecting for minerals or oils on or near them. The points set out in your paragraph 1 should not therefore arise but I shall nevertheless give them further consideration in view of your request.⁷⁶

On 12 November 1965, the Governor of Mauritius cabled the Colonial Office, querying whether the Mauritian Ministers could make public reference to the items in paragraph 22 of the record of the Lancaster House Meeting and adding "[i]n this connection I trust further consideration promised... will enable categorical assurances to be given."⁷⁷

On 19 November 1965, the Colonial Office cabled the Governor of Mauritius as follows:

U.K./U.S. defence interests.

There is no objection to Ministers referring to points contained in paragraph 22 of enclosure to Secret despatch No. 423 of 6th October so long as qualifications contained in paragraphs 5 and 6 of the despatch are borne in mind.

2. It may well be some time before we can give final answers regarding points (iv), (v) and (vi) of paragraph 22 and as you know we cannot be at all hopeful for concessions over sugar imports and it would therefore seem unwise for anything to be said locally which would raise expectations on this point.

3. As regards point (vii) the assurance can be given provided it is made clear that a decision about the need to retain the islands must rest entirely with the United Kingdom Government and that it would not (repeat not) be open to the Government of Mauritius to raise the matter, or press for the return of the islands on its own initiative.

4. As stated in paragraph 2 of my telegram No. 298 there is no intention of permitting prospecting for minerals and oils. The question of any benefits arising therefrom should not [...] [illegible]⁷⁸

On 21 December 1965, in response to questions in the Mauritius Legislative Assembly regarding the obligations agreed to by the United Kingdom, Mr Forget (on behalf of the Premier and Minister of Finance) identified the following agreements (among other points):

[...]

(e) If the British Government decides that the Chagos Archipelago is no longer required for defence purposes, the islands will be returned to Mauritius. The question what would happen in such circumstances to any installations in the Chagos Archipelago is, of course, a hypothetical one, and would no doubt be discussed between the interested Governments in light of practical requirements and considerations at the time.

[...]

(i) The Honourable Member’s question is, again, a hypothetical one and I should make clear that there has never been any indication of minerals in the Chagos Archipelago, which is a string of coral atolls. The British Government has no intention of allowing prospecting for minerals while the islands are being used for defence purposes. For the position thereafter, I would refer the Honourable Member to the first sentence of the reply to Question (e).⁷⁹

Following the public announcement of the detachment of the Chagos Archipelago, the matter was raised in the Special Committee on the Situation with regard to the Implementation of the Declaration on the Granting of Independence to Colonial Countries and Peoples. On 16 December 1965, the Generally Assembly adopted Resolution 2066(XX) as follows:

2066 (XX). Question of Mauritius

The General Assembly,

Having considered the question of Mauritius and other islands composing the Territory of Mauritius,

Having examined the chapters of the reports of the Special Committee on the Situation with regard to the Implementation of the Declaration on the Granting of Independence to Colonial Countries and Peoples relating to the Territory of Mauritius,¹⁶

Recalling its resolution 1514 (XV) of 14 December 1960 containing the Declaration on the Granting of Independence to Colonial Countries and Peoples,

Regretting that the administering Power has not fully implemented resolution 1514 (XV) with regard to that Territory,

Noting with deep concern that any step taken by the administering Power to detach certain islands from the Territory of Mauritius for the purpose of establishing a military base would be in contravention of the Declaration, and in particular of paragraph 6 thereof,

1. Approves the chapters of the reports of the Special Committee on the Situation with regard to the Implementation of the Declaration on the Granting of Independence to Colonial Countries and Peoples relating to the Territory of Mauritius, and endorses the conclusions and recommendations of the Special Committee contained therein ;

2. Reaffirms the inalienable right of the people of the Territory of Mauritius to freedom and independence in accordance with General Assembly resolution 1514 (XV);

3. Invites the Government of the United Kingdom of Great Britain and Northern Ireland to take effective measures with a view to the immediate and full implementation of resolution 1514 (XV);

4. Invites the administering Power to take no action which would dismember the Territory of Mauritius and violate its territorial integrity;

5. Further invites the administering Power to report to the Special Committee and to the General Assembly on the implementation of the present resolution;

6. Requests the Special Committee to keep the question of the Territory of Mauritius under review and to report thereon to the General Assembly at its twenty-first session.

1398th plenary meeting,

16 December 1965.⁸⁰

The status of Mauritius was also raised, along with that of other non-self-governing territories, in General Assembly resolutions adopted on 20 December 1966⁸¹ and 19 December 1967.⁸²

In 1975, in anticipation of the transition of the Seychelles to independence the following year, the United Kingdom and the United States entered into discussions on the possibility of returning Aldabra, Farquhar and Desroches to the Seychelles. Neither the United Kingdom nor the United States saw any defence need for the islands, and the United Kingdom considered that the return would facilitate a smooth transition.⁸³ It was also recognized that the islands remained populated and that the political repercussions of the resettlement of the Chagossians⁸⁴ (discussed below) would render it impractical to take similar steps on the other BIOT islands. On 18 March 1976, the United States, United Kingdom, and Seychelles reached an agreement to return the islands, with effect from the independence of the Seychelles on 29 June 1976, in exchange for a commitment by the Seychelles not to permit military access to the islands by third States and to continue a policy of strict nature conservancy, in particular with respect to Aldabra.⁸⁵ The agreement was given effect by the adoption on 9 June 1976 of an Order in Council.⁸⁶

At the time of the detachment of the Chagos Archipelago in 1965, there were approximately 1,360 persons resident on the islands.⁸⁷ Including those born on the islands, the total Chagossian population may be considered to have been between 1,500 and 1,750 persons.⁸⁸

On 30 December 1966, the United Kingdom and the United States concluded an Agreement Concerning the Availability for Defense Purposes of the British Indian Ocean Territory which provided for "the islands [to] be available to meet the needs of both Governments for defense" and that "required sites [for defence facilities] shall be made available to the United States authorities without charge".⁸⁹ Pursuant to a further exchange of notes, kept secret at the time, the United States agreed to contribute £5 million to the costs of establishing the BIOT, to be paid by waiving United Kingdom payments in respect of joint missile development⁹⁰ programmes.

Between 1968 and 1973, the United Kingdom proceeded to arrange for the purchase of privately held land and to remove the Chagossian population from the Archipelago. On 16 April 1971, the BIOT Commissioner passed Immigration Ordinance, 1971, which provided in section 4 that "[n]o person shall enter the Territory or, being in the Territory, shall be present or remain in the Territory, unless he is in possession of a permit or his name is endorsed on a permit in accordance with the provisions of... this Ordinance".⁹¹ The record indicates that the resettlement and compensation of the Chagossian population had been contemplated in discussions with the United States as early as January 1964,⁹² and the Lancaster House Undertakings (see above at paragraph 77) included reference to "direct compensation to landowners and the cost of resettling others affected in the Chagos Islands."⁹³

Further to talks conducted in early 1972, the United Kingdom agreed to pay Mauritius the sum of £650,000 as compensation for the costs of resettling persons displaced from the Chagos Archipelago.⁹⁴

In 1975, a former resident of the Chagos Archipelago, Mr Michel Vencatassen, initiated a claim for compensation in the courts of England and Wales against the British Government. This was settled in 1982 with an agreement in which the United Kingdom would pay £4 million into a fund for the former residents of the Archipelago.⁹⁵ On 7 July 1982, Mauritius and the United Kingdom concluded an agreement pursuant to which -

The Government of the United Kingdom shall ex gratia with no admission of liability pay to the Government of Mauritius for and on behalf of the Ilois⁹⁶ and the Ilois community in Mauritius in accordance with Article 7 of this Agreement the sum of £4 million which, taken together with the payment of £650,000 already made to the Government of Mauritius, shall be in full and final settlement of all claims [arising from the removal or resettlement of the population of the Chagos Archipelago].⁹⁷

The 1982 agreement was then implemented in Mauritius by the Ilois Trust Fund Act of 30 July 1982.⁹⁸

In 1998, another former resident of the Chagos Archipelago, Mr Olivier Bancoult, sought judicial review in the courts of England and Wales of section 4 of the BIOT Immigration Ordinance, 1971 (see paragraph 90 above). On 3 November 2000, the High Court held that "there is no principled basis upon which s.4 of the Ordinance can be justified as having been empowered by s.11 of the BIOT Order",⁹⁹ insofar as the removal of the Chagossian population did not fall within the Commissioner’s power to "make laws for the peace, order and good government of the Territory".¹⁰⁰

On 3 November 2000, the Commissioner enacted the BIOT Immigration Ordinance, 2000, which restricted access to the Archipelago, but included an exception allowing Chagossians entry, except with respect to Diego Garcia.

In April 2002, a group of 4,959 former residents of the Chagos Archipelago and their descendants brought a claim against the Attorney General of England and Wales and the BIOT Commissioner for compensation and restoration of property rights. On 9 October 2003, the High Court dismissed this action on the grounds that no tort at common law was committed by the removal of the Chagossian population and that further compensation for property loss was precluded by the Limitation Act, 1980 and the Claimants’ renunciation of claims in exchange for the compensation provided in 1982.¹⁰¹

On 10 June 2004, the United Kingdom adopted, by Order in Council, the British Indian Ocean Territory (Constitution) Order, 2004, which provided in section 9 as follows:

No right of abode in the Territory

9. - (1) Whereas the Territory was constituted and is set aside to be available for the defence purposes of the Government of the United Kingdom and the Government of the United States of America, no person has the right of abode in the Territory.

(2) Accordingly, no person is entitled to enter or be present in the Territory except as authorised by or under this Order or any other law for the time being in force in the Territory.¹⁰²

On the same day, the United Kingdom adopted, by Order in Council, the British Indian Ocean Territory (Immigration) Order, 2004, replacing BIOT Immigration Ordinance, 2000 and removing the exception allowing Chagossians entry, except with respect to Diego Garcia. The Order also created a penal offence of unlawful entry into the territory.¹⁰³

In August 2004, Mr Bancoult initiated proceedings seeking judicial review of the 2004 Orders in Council. After decisions in the High Court¹⁰⁴ and Court of Appeal¹⁰⁵ quashing section 9 of the (Constitution) Order, 2004 as irrational insofar as it was unconnected to the well-being of the Chagossian population, the House of Lords (by three votes to two) allowed an appeal by the Secretary of State. In so doing, the House of Lords held (per Lord Hoffmann) that "Her Majesty exercises her powers of prerogative legislation for a non-self-governing colony on the advice of her ministers in the United Kingdom and will act in the interests of her undivided realm, including both the United Kingdom and the colony"¹⁰⁶ and that, in light of the assessment that resettlement was economically unviable and the Chagossian interest in funded resettlement, it was "impossible to say, taking fully into account the practical interests of the Chagossians, that the decision to reimpose immigration control on the islands was unreasonable or an abuse of power."¹⁰⁷

Thereafter, Mr Bancoult and other Chagossians pursued their claims before the European Court of Human Rights. In December 2012, the European Court held in Chagos Islanders v. The United Kingdom that the claim was inadmissible, on the grounds that -

in settling their claims in the Ventacassen litigation and in accepting and receiving compensation, those applicants have effectively renounced further use of these remedies. They may no longer, in these circumstances, claim to be victims of a violation of the [European Convention on Human Rights], within the meaning of Article 34 of the [European Convention on Human Rights]. Those applicants who were not party to the proceedings but who could at the relevant time have brought their claims before the domestic courts have, for their part, failed to exhaust domestic remedies as required by Article 35 § 1 of the [European Convention on Human Rights].¹⁰⁸

In the course of the proceedings before the present Tribunal, the Attorney-General of England and Wales, the Rt. Hon. Dominic Grieve QC MP made the following statement regarding the Chagossian population:

we regret very much the circumstances in which they were removed from the islands and recognise that what was done then should not have happened. A substantial sum in compensation was paid to the former inhabitants in the 1980s—a point that was recognised by the European Court of Human Rights in their recent decision. When in Opposition, the political party of which I'm a member said that we would look again at our current policy for BIOT. When we first came into Government, we were constrained by the proceedings in the European Court of Human Rights. But immediately after those proceedings were concluded, my colleague, the Foreign Secretary, announced that we would be looking again at the question of the United Kingdom’s policy towards BIOT. As part of that review we are looking again at the question of resettlement. And we hope to be able to reach conclusions in the early part of next year in respect of that.¹⁰⁹

Between 1968 and 1980, Mauritius generally did not raise the question of the Chagos Archipelago in public fora and diplomatic communications. The Parties differ as to the significance of the absence of public claims by Mauritius. In Mauritius’ view, this silence must be understood in light of the "difficult socio-economic situation" and Mauritius’ heavy reliance on the United Kingdom in the years following independence.¹¹⁰ According to the United Kingdom, the silence indicates that "until 1980, the then Government of Mauritius did not question the obvious fact that at independence the BIOT was not part of the territory of the Republic of Mauritius."¹¹¹

On 7 July 1982, following elections and a change of government, the Parliament of Mauritius adopted the Interpretation and General Clauses (Amendment) Act, 1982, which incorporated the Chagos Archipelago into the definition of Mauritius for the purposes of Mauritian law as follows:

Section 2(b) of the [Interpretation and General Clauses Act] is amended in the definition of "State of Mauritius" or "Mauritius" by deleting the words "Tromelin and Cargados Carajos" and replacing them by the words "Tromelin, Cargados Carajos and the Chagos Archipelago, including Diego Garcia".¹¹²

On 21 July 1982, the Parliament of Mauritius established a Select Committee on the Excision of the Chagos Archipelago to examine the circumstances of the detachment of the islands. The Select Committee interviewed surviving participants of the events of 1965, although their recollections were inconsistent and differed in material respects from the documentary record set out above (see paragraphs 69-85). The Select Committee’s Report was published on 1 June 1983 and was strongly critical of the detachment of the Archipelago, the lack of transparency with which the pre-independence Government of Mauritius handled the matter, and the lack of candour of a number of the participants in their testimony to the Committee. The Select Committee also identified what it described as a "blackmail element" in the way in which the question of detachment had been presented by the United Kingdom and concluded that detachment had represented a violation of the UN Charter.¹¹³

Since 1980, Mauritius contends that "[i]t has consistently asserted its rights [to sovereignty over the Chagos Archipelago] in statements to the UN General Assembly".¹¹⁴ According to Mauritius, it "has also consistently asserted its sovereignty over the Chagos Archipelago in bilateral communications with the UK".¹¹⁵ The Parties differ as to whether Mauritius’ statements to the United Nations indicate a claim of current sovereignty or simply a claim to the eventual return of the islands, pursuant to the United Kingdom’s undertaking, when no longer required for defence purposes. In either event, the United Kingdom has consistently responded by maintaining its view that the Chagos Archipelago remains British.¹¹⁶

In its 1992 Constitution, Mauritius incorporated the following definition of Mauritius:

Mauritius’ includes -

(a) the Islands of Mauritius, Rodrigues, Agalega, Tromelin, Cargados Carajos and the Chagos Archipelago, including Diego Garcia and any other island comprised in the State of Mauritius;

(b) the territorial sea and the air space above the territorial sea and the islands specified in paragraph (a);

(c) the continental shelf; and

(d) such places or areas as may be designated by regulations made by the Prime Minister, rights over which are or may become exercisable by Mauritius.¹¹⁷

On 31 May 1977, Mauritius adopted its Maritime Zones Act, 1977.¹¹⁸ On 27 December 1984, Mauritius adopted the Maritime Zones (Exclusive Economic Zones) Regulations, 1984, setting out, inter alia, the coordinates of the exclusive economic zone surrounding the Chagos Archipelago.¹¹⁹ The United Kingdom protested against this action on 18 February 1985.¹²⁰

On 25 July 1997, the United Kingdom acceded to the Convention, with an Instrument of Accession extending to the BIOT. Mauritius did not object. According to Mauritius, limited resources inhibit its ability to track all accessions to multilateral treaties that may implicate the Chagos Archipelago, but "[w]henever Mauritius has noted that a multilateral convention has been so extended, it has not failed to protest."¹²¹ Mauritius did object to the extension of the Agreement for the Implementation of the Provisions of the United Nations Convention on the Law of the Sea of 10 December 1982 Relating to the Conservation and Management of Straddling Fish Stocks and Highly Migratory Fish Stocks of 4 August 1995 (the "1995 Fish Stocks Agreement")¹²² and has stated in these proceedings that "Mauritius does not accept that the United Kingdom is entitled to extend the territorial scope of its treaty obligations to the Archipelago."¹²³

On 28 February 2005, Mauritius adopted the Maritime Zones Act, 2005, replacing earlier legislation.¹²⁴ Pursuant to this Act, on 5 August 2005, Mauritius adopted the Maritime Zones (Baselines and Delineating Lines) Regulations, 2005, setting out the geographical coordinates for the baselines of, inter alia, the Chagos Archipelago.¹²⁵ On 26 July 2006, Mauritius conveyed these geographical coordinates to the UN Secretary-General...¹²⁶ On 27 June 2008, Mauritius made a further deposit of charts and geographical coordinates with the United Nations.¹²⁷ On 19 March 2009, the United Kingdom protested against Mauritius’ deposit of information in respect of the Chagos Archipelago.¹²⁸ On 9 June 2009, Mauritius reiterated its non-recognition of the BIOT to the United Nations.¹²⁹

On 14 January 2009, in talks (conducted under a sovereignty umbrella) between the United Kingdom and Mauritius concerning the Chagos Archipelago, the United Kingdom indicated that it was not interested in making a submission to the Commission on the Limits of the Continental Shelf, but was open to the possibility of a joint submission with Mauritius in light of the impending deadlines for States Parties to submit preliminary information.¹³⁰ The content of these discussions is set out in detail below in connection with the Tribunal’s consideration of its jurisdiction over Mauritius’ Third Submission (see paragraphs 331-343).

On 6 May 2009, Mauritius submitted preliminary information concerning the outer limits of the continental shelf in the Chagos Archipelago to the CLCS.¹³¹

On 21 July 2009, a second round of Mauritius-United Kingdom talks took place (again under a sovereignty umbrella), in which submissions to the CLCS were discussed. The United Kingdom did not object to Mauritius’ submission of preliminary information to the CLCS, and the Parties agreed to move forward with the joint preparation of a full submission.¹³² The Joint Communiqué issued after the talks stated as follows:

Both delegations were of the view that it would be desirable to have a coordinated submission for an extended continental shelf in the Chagos Archipelago/British Indian Ocean Territory region to the UN Commission on the Limits of the Continental Shelf, in order not to prejudice the interest of Mauritius in that area and to facilitate its consideration by the Commission. It was agreed that a joint technical team would be set up with officials from both sides to look into possibilities and modalities of such a coordinated approach, with a view to informing the next round of talks.¹³³

A third round of joint talks was proposed for November 2009 or January 2010,¹³⁴ but did not take place in light of developments discussed below (see paragraphs 131-141).

In its Rejoinder in these proceedings, submitted on 14 March 2014, the United Kingdom commented on Mauritius’ submission of preliminary information to the CLCS as follows:

Mauritius cannot alter the status of the BIOT continental shelf by making its own submission to the CLCS with respect to BIOT. [...] In accordance with the terms of article 76(7), only the coastal State may delineate the outer limits of the continental shelf. In accordance with article 76(8), only the coastal State may submit information to the CLCS on the limits of the shelf beyond 200 nautical miles. Mauritius is not the coastal State in respect of BIOT and as such it has no standing before the CLCS with respect to BIOT.¹³⁵

Following the detachment of the Chagos Archipelago, the Colonial Office cabled the Governor of Mauritius on 10 November 1965, seeking details of the nature and extent of fishing around the islands.¹³⁶ On 17 November 1965, the Governor replied as follows:

(a) Nature fishing practised: mainly handline with some basket and net fishing by local population for own consumption.

(b) Use of international waters: nil, though vessels from Seychelles and occasionally Mauritius use anchorage facilities.

(c) Extent territorial waters: unknown. Area covered by banks (up to 80 fathoms) about 6,000 square miles.

(d) Value as source of fish: best reference report Wheeler Ommaney, Mauritius Seychelles Fisheries Survey. Fishable area roughly 2,433 square miles. Available potential: fish 95,000 tons, shark 147,000 tons.¹³⁷

Following correspondence exchanged with the Governor of Mauritius¹³⁸, BIOT officials¹³⁹, and officials in the United States¹⁴⁰ regarding the form of fishing limits, the BIOT Commissioner established a fisheries zone contiguous to the territorial sea of the BIOT on 10 July 1969. This fisheries zone extended from the outer limit of the (then) 3 nautical mile territorial sea to 12 nautical miles from the low waterline (or otherwise from the baselines from which the territorial sea was measured).¹⁴¹

On 17 April 1971, the BIOT Commissioner enacted the Fisheries Limits Ordinance, 1971. The ordinance imposed a general prohibition of commercial fishing within the 12 nautical mile limit set out therein. Section 4 empowered the Commissioner "for the purpose of enabling fishing traditionally carried on in any area within the contiguous zone" to designate countries whose nationals would be exempted from the prohibition.¹⁴²

On 2 July 1971, the British High Commission in Port Louis was directed in the following terms to inform Mauritius that Mauritian fishermen would be exempted from the ordinance:

Included within the BIOT fishing zone are certain waters which have been traditionally fished by vessels from Mauritius. [...] the Commissioner of BIOT will use his powers under Section 4 of BIOT Ordinance No 2/1971, to enable Mauritian fishing boats to continue fishing in the 9-mile contiguous zone in the waters of the Chagos Archipelago. This exemption stems from the understanding on fishing rights reached between HMG and the Mauritius Government, at the time of the Lancaster House Conference in 1965 [...]. We would be most grateful if you would inform the Mauritius Government of the foregoing at whatever level you consider appropriate.¹⁴³

Although the record does not indicate any order formally designating Mauritius pursuant to Section 4 of the ordinance, the BIOT Administrator reported in 1972 that "Mauritians have been declared as traditional fishermen in BIOT as the islands formerly formed part of Mauritius."¹⁴⁴ The Parties are, in any event, agreed that the "understanding was that Mauritian-flagged vessels were designated to fish in the 3nm-12nm contiguous zone."¹⁴⁵

By July 1983, the United Kingdom had noted the absence of an order formally designating Mauritius for the purposes of the 1971 Ordinance and was considering steps to "regularise the position."¹⁴⁶ Shortly thereafter, the discovery in August 1983 that several Mauritian fishing vessels were operating in the territorial sea around the Chagos Archipelago without the knowledge of British officials, and were also gathering coconuts on the outlying islands, prompted the United Kingdom to "look afresh at [its] policy on access by Mauritian vessels to BIOT".¹⁴⁷

On 12 August 1984, the BIOT Commissioner adopted the Fishery Limits Ordinance, 1984 and repealed the 1971 Ordinance.¹⁴⁸ The new ordinance provided for the designation of particular States as eligible to fish in the territorial sea and contiguous zone surrounding the Chagos Archipelago. Following designation, vessels from such States were required to comply with a licensing regime to specify the type of fishing and areas in which it could be carried out. On 21 February 1985, Mauritius was formally designated pursuant to the Fisheries Limit Ordinance, 1984 "for the purpose of enabling fishing traditionally carried on in any area within the fishery limits to be continued by fishing boats registered in Mauritius".¹⁴⁹

On 23 July 1991, the United Kingdom wrote to Mauritius, providing advance notice that the Commissioner would shortly declare a 200 nautical mile Fisheries Conservation and Management Zone ("FCMZ") in the waters surrounding the Chagos Archipelago. The United Kingdom explained the measure in the following terms:

There are good environmental reasons for this action. Tuna stocks migrate around the Indian Ocean, large numbers passing through the area to be included in the 200 mile zone. In the view of the British Government on the advice of technical experts, it is important that these waters are subject to regulatory control through licensing. If we fail to exercise our responsibilities stocks will dwindle to the detriment of other Indian Ocean states and territories. It is important also that we conserve the stock position and so protect the future fishing interests of the Chagos group. An extension of the zone will allow the application of regulations relating to types of net and fishing gear.

In view of the traditional fishing interests of Mauritius in the waters surrounding British Indian Ocean Territory, a limited number of licences free of charge have been offered to artisanal fishing companies for inshore fishing. We shall continue to offer a limited number of licences free of charge on this basis.¹⁵⁰

Mauritius responded to this communication by reiterating its claim to sovereignty over the Chagos Archipelago.¹⁵¹

On 1 October 1991, the BIOT Commissioner issued a Proclamation establishing the FCMZ.¹⁵² On the same day, the BIOT Commissioner adopted the Fisheries (Conservation and Management) Ordinance, 1991, replacing the Fisheries Limit Ordinance, 1984.¹⁵³ The 1991 Ordinance extended the licensing regime of the 1984 Ordinance, but no longer required the prior designation of a State as a criteria for licensing.

On 1 July 1992, the United Kingdom informed Mauritius in the following terms that it would continue to issue fishing licenses for Mauritian vessels free of charge:

There are no plans to establish an exclusive economic zone around the Chagos islands. HMG takes seriously its obligations to ensure the conservation of the resources of the Archipelago and declared a 200 mile exclusive fishing zone on 1 October 1991 as its contribution to safeguarding the tuna and other fish stocks of the Indian Ocean. The British Government has honoured the commitments entered into in 1965 to use its good offices with the United States Government to ensure that fishing rights would remain available to Mauritius as far as practicable. It has issued free licences for Mauritius fishing vessels to enter both the original 12 mile fishing zone of the territory and now the wider waters of the exclusive fishing zone. It will continue to do so, provided that the Mauritian vessels respect the licence conditions laid down to ensure proper conservation of local fishing resources.¹⁵⁴

On 27 January 1994, Mauritius and the United Kingdom established the British-Mauritian Fisheries Commission to address the conservation of fish stocks. In the Joint Statement setting out the creation of the Commission, the Parties agreed to a comprehensive "sovereignty umbrella" pursuant to which neither the creation of the Commission nor any activity carried out pursuant to it would be understood to prejudice the Parties’ respective positions regarding the Chagos Archipelago.¹⁵⁵

On 13 August 2003, the United Kingdom informed Mauritius in the following terms that it intended to establish an Environmental Protection and Preservation Zone ("EPPZ") encompassing the same geographical area of the FCMZ:

The Government of Mauritius will wish to be aware that in order to help preserve and protect the environment of the Great Chagos Bank, the British Government proposes to issue a similar Proclamation [to the FCMZ] by the Commissioner for BIOT, but this time establishing an Environmental (Protection and Preservation) Zone. This will be defined so as to have the same geographical extent as BIOT’s FCMZ. It will not involve any change in the land areas comprised within BIOT. A copy of the Proclamation, together with copies of the relevant charts and co-ordinates, will be deposited with the UN under Article 75 of UNCLOS later this year.¹⁵⁶

On 17 September 2003, the BIOT Commissioner issued British Indian Ocean Territory Proclamation No. 1 of 2003, establishing the EPPZ.¹⁵⁷ In response to concerns raised by Mauritius over the EPPZ,¹⁵⁸ the United Kingdom stated that the nature of the FCMZ/EPPZ was not a full exclusive economic zone for all purposes.¹⁵⁹ The United Kingdom deposited the geographical coordinates for the EPPZ with the UN Secretary-General on 12 March 2004.¹⁶⁰ Mauritius protested against this deposit on 14 and 20 April 2004.¹⁶¹

The Parties differ regarding the scale and significance of the fishing conducted by Mauritian vessels pursuant to the foregoing regime. The United Kingdom looks at the number of licences issued by the BIOT administration and concludes that "the take-up of commercial fishing licenses by Mauritian-flagged vessels was very low, in some years nil".¹⁶² Mauritius relies on the catch data of its Ministry of Fisheries to conclude that "there have been catches by Mauritian fishing vessels in Chagos Archipelago since at least 1977. The mean annual catch is 164 tons."¹⁶³

On 9 February 2009, the London newspaper The Independent reported that a giant marine park was planned for the Chagos Archipelago.¹⁶⁴ This publication prompted the Mauritian Ministry of Foreign Affairs, Regional Integration and International Trade, the following month, to reiterate its view on sovereignty over the Chagos Archipelago:

both under Mauritian law and international law, the Chagos Archipelago is under the sovereignty of Mauritius [...] The creation of any Marine Park in the Chagos Archipelago will therefore require, on the part of all parties that have genuine respect for international law, the consent of Mauritius.¹⁶⁵

In response, the United Kingdom FCO reiterated that it had no doubts regarding the United Kingdom’s sovereignty over the BIOT and stated further as follows:

the proposal for a marine park in the Chagos Archipelago (BIOT) is the initiative of the Chagos Environment Network and not of the Government of the United Kingdom of Great Britain and Northern Ireland. However, the Government of the United Kingdom of Great Britain and Northern Ireland welcomes and encourages recognition of the global importance of the British Indian Ocean Territory and notes the very high standards of preservation there that have been made possible by the absence of human settlement in the bulk of the territory and the environmental stewardship of the BIOT Administration and the US military.¹⁶⁶

During the second round of Mauritius-United Kingdom joint talks on 21 July 2009 (see paragraph 110 above), the issue of a potential marine protected area was raised. The United Kingdom’s account of the meeting records the following:

8. The UK delegation explained that environmental law had been strengthened in BIOT over the last 15 years with the establishment of strict nature reserves, Ramsar designation in [Diego Garcia] and the establishment of an EPPZ. The Territory and its environs had become one of the most valuable sites in the world for coral biodiversity and also had the cleanest oceans and was a valuable scientific resource. This was due to lack of inhabitants. The UK derived no commercial benefit from resources. The fishery was a loss-making venture and heavily subsidised by HMG. Looking ahead, the value of BIOT as a reserve/sanctuary for marine life and coral would only increase. It was better to invest available resources in a higher level of environmental protection. There was a proposal from the Chagos Environment Network (CEN). One of the ideas being mooted was that the whole of the EEZ be a no-take zone for fishing. The scientific basis had not yet been fully established but the idea merited consideration. An alternative route would be a more gradual process, i.e., to designate the reefs as no take or another proposal of a different / larger area than that of the closure of reef areas extending 12 n miles from the 200m depth contour and leave the rest of the fishery open.

9. There were powerful arguments in the UK to establish a marine protected area. However, many questions still needed to be worked through. The UK delegation explained the advantage to Mauritius that through a marine protected area, the value of the Territory would be raised and this resource would eventually be ceded to Mauritius. No decisions had yet been taken. The UK was discussing issues with the US: BIOT was created for defence purposes and the environmental agenda must not overcome that purpose.

10. The Mauritian delegation explained that they had taken exception to the proposal from the CEN but on the basis that it implied that the Mauritians had no interest in the environment. They had also found it necessary to protest on sovereignty grounds. There was a general agreement that scientific experts should be brought together. However, the Mauritians welcomed the project but would need to have more details and understand the involvement of the Mauritian government. The UK delegation explained that not many details were available as the UK wanted to talk to Mauritius before proposals were developed. If helpful the UK could, for the purposes of discussion, produce a proposal with variations on paper for the Mauritians to look at.

11. The UK delegation added that the Foreign Secretary was minded to go towards a consultative process and that would be a standard public consultation, However, the UK had wanted to speak to Mauritius about the ideas beforehand. Also, we needed to bear in mind the case before the [European Court of Human Rights]. Any ideas proposed would be without prejudice to any judgment by the Court.¹⁶⁷

The Mauritian account records the same exchanges in the following terms:

(v) Establishment of Marine Protected Area

This item was included at the request of the British side. It explained that the UK Government wished to start dialogue on a proposal made by a British Non-Governmental Organisation to establish a marine protected area in the region of the Chagos Archipelago.

The British side supports the proposal for the following reasons:

(a) the region is still pristine as a result of non-settlement; and should remain one of the very few such rare areas in the world;

(b) the benefits out of fishing activities accrue mostly to developed countries rather than to those of the region; and

(c) the conservation and preservation of the pristine environment outweighs, by far, the benefits derived from fishing activities.

In reply, the Mauritian side while expressing concern that the matter was not a subject of prior discussions with Mauritius, welcomed the proposal, since it concerns the protection of the environment, the moreso that it is in line with the policy of Government to promote sustainable development.

The Mauritius side asked for additional details in respect of the proposed project.

The Mauritian side agreed that a team of officials and marine scientists from both sides meet to examine the implications of the concept with a view to informing the next round of talks. The British side made it clear that any proposal for the establishment of the marine protected area would be without prejudice to the outcome of the decision at the European Court of Human Rights.¹⁶⁸

The Joint Communiqué issued following the talks stated:

The British delegation proposed that consideration be given to preserving the marine biodiversity in the waters surrounding the Chagos Archipelago/British Indian Ocean Territory by establishing a marine protected area in the region. The Mauritian side welcomed, in principle, the proposal for environmental protection and agreed that a team of officials and marine scientists from both sides meet to examine the implications of the concept with a view to informing the next round of talks. The UK delegation made it clear that any proposal for the establishment of the marine protected area would be without prejudice to the outcome of the proceedings at the European Court of Human Rights.¹⁶⁹

On 10 November 2009, the United Kingdom initiated a public consultation process regarding the potential creation of the MPA (the "Public Consultation"). On the same day, the British High Commissioner provided the Foreign Minister of Mauritius, Dr Arvin Boolell, with a copy of the Public Consultation document¹⁷⁰ and the United Kingdom’s Foreign Secretary placed a call to the Prime Minister of Mauritius, Dr Navinchandra Ramgoolam.¹⁷¹ The United Kingdom’s record of this telephone call read as follows:

The Foreign Secretary said that he understood that UK and Mauritian officials had been talking very productively about a marine protected area being created during the bilateral discussions on areas of mutual cooperation on BIOT. He wanted to reassure PM Ramgoolam that the public consultation being launched was on the idea of an MPA and it was only an idea at this point. Going out to consultation was the right thing to do before making any decisions. We would talk to Mauritius before we made any final decision. Mauritian views were important. We were arranging a facilitator to travel out to Port Louis and to Victoria in January to hold meetings with all interested parties. While the focus would be on the Chagossian community, the facilitator would also listen to other peoples’ views.

The Foreign Secretary reassured PM Ramgoolam that there would be no impact on the UK commitment to cede the Territory to Mauritius when it was no longer needed for defence purposes. In the meantime, an MPA provided a demonstration of our bilateral relationship of trust and would make something of the remarkable features that exist in BIOT. He hoped the UK and Mauritius could work closely together on this.

PM Ramgoolam responded that environmental protection was an important subject for him. He had a few problems with the consultation document which he had only just seen and would be sending a Note Verbale on this. His first problem was on page 12 "we {Mauritius} have agreed in principle to the establishment of an MPA". This was not the case. Could we amend the consultation document?

In addition Mr Ramgoolam said that the consultation document completely overlooked the issue of resettlement. A total ban on fishing would not be conducive to resettlement. Neither was there any mention of the sovereignty issue. PM Ramgoolam did not want the MPA consultation to take place outside of the bilateral talks between the UK and Mauritius on Chagos.

The Foreign Secretary said he hoped there had been no misunderstanding. He understood that the discussions between the UK and Mauritius had been positive. He would ask officials to look at page 12 of the consultation document. Comment : we have amended the language in page 12 to reflect more closely the wording in the communiqué. He added that while the bilateral talks were an important forum, the purpose of the consultation was to bring the idea of an MPA to a wider public. Neither the consultation nor any decision would prejudice the court cases or any of the issues PM Ramgoolam referred to. He hoped PM Ramgoolam would see that the consultation was a positive thing.

PM Ramgoolam repeated his point that a ban on fishing would be incompatible with resettlement. The Foreign Secretary suggested he make that point in the consultation but there were all sorts of ways of organising sustainable fishing. Resettlement was a different question and would take enormous resources regardless of which Government did this. He knew that PM Ramgoolam was aware of the Government’s strong position on this issue.

PM Ramgoolam said he had a problem with the consultation document saying that the BIOT Commissioner would make the declaration of an MPA. They wanted it to be declared by the UK Government as Mauritius did not recognise BIOT. He pointed out that he had elections next year. Comment : this should not be an insurmountable problem. The Foreign Secretary might instruct the BIOT Commissioner to declare an MPA and make this clear in any press release.

The Foreign Secretary said he believed that there was nothing in the document that weakened the Mauritian claim on sovereignty. There was no reason for Mauritius to criticise Ramgoolam on that score. The UK commitment to cede the Territory was as before. He added that he had a lot of respect for PM Ramgoolam’s political skills and could not see the consultation being a problem for PM Ramgoolam.

PM Ramgoolam said he would take up the issue with Gordon Brown at CHOGM. He asked if the subject could be brought up at the next bilateral talks. The Foreign Secretary agreed that it could be.¹⁷²

On the same day, Mauritius wrote to the British High Commission regarding the consultation document’s representation of Mauritian support for the MPA:

The Ministry of Foreign Affairs, Regional Integration and International Trade wishes to inform the High Commission that the Government of the Republic of Mauritius has not welcomed the establishment of a marine protected area during the bilateral talks on the Chagos Archipelago held in Mauritius last July, contrary to what is stated at page 12 of the Consultation Document.

In that regard, the Ministry of Foreign Affairs, Regional Integration and International Trade would like to point out that what was stated in the Joint Communiqué issued following the bilateral talks of last July was that the Mauritian side had welcomed, in principle, the proposal for environmental protection and agreed that a team of officials and marine scientists from both sides would meet to examine the implications of the concept with a view to informing the next round of talks.

The Ministry of Foreign Affairs, Regional Integration and International Trade therefore requests that the Foreign and Commonwealth Office accordingly amend its Consultation Document to accurately reflect the position of the Government of the Republic of Mauritius.¹⁷³

The United Kingdom indicated in the following terms that it would correct the consultation document:

The British High Commission would like to underline that the purpose of the consultation is to gain views on a proposal made by an environmental NGO: the Chagos Conservation Trust. No policy decision has been made on the issue in hand. Our approach aims to be consultative and inclusive: the Chagos Conservation Trust’s MPA proposal was discussed with the Government of Mauritius in bilateral talks on BIOT/Chagos Islands prior to the launch of the public consultation. We anticipate further discussion in the next round of bilateral talks, which we had hoped to hold this month, but which now look likely to be held in early 2010.

In light of this constructive and ongoing dialogue, the British High Commission would like to reassure the Ministry of Foreign Affairs, Regional Integration and International Trade that no offence was intended by the wording on page 12 of the draft consultation document that was shared with you on 10 November. We were, therefore, happy to amend the wording of the final document (released later that day on the following site: (http://www.ukinmauritius.fco.gov.uk) to reflect the views expressed in your Note Verbale.¹⁷⁴

On 23 November 2009, Mauritius wrote further to the United Kingdom as follows:

The Ministry of Foreign Affairs, Regional Integration and International Trade, whilst welcoming the amendment at page 12 of the Consultation Document, regrets to note that the precise stand of the Mauritian side on the MPA project, as stated in the Joint Communiqué issued following the bilateral talks of last July and in its Note Verbale of 10 November 2009, has not been fully reflected in the amended Consultation Document. That stand, as per the Joint Communiqué, reads as follows:-

"The Mauritian side welcomed, in principle, the proposal for environmental protection and agreed that a team of officials and marine scientists from both sides meet to examine the implications of the concept with a view to informing the next round of talks".

Furthermore, the Ministry of Foreign Affairs, Regional Integration and International Trade would like to state that since there is an on-going bilateral Mauritius-UK mechanism for talks and consultations on issues relating to the Chagos Archipelago and a third round of talks is envisaged early next year, the Government of the Republic of Mauritius believes that it is inappropriate for the consultation on the proposed marine protected area, as far as Mauritius is concerned, to take place outside this bilateral framework.

The Government of Mauritius considers that an MPA project in the Chagos Archipelago should not be incompatible with the sovereignty of the Republic of Mauritius over the Chagos Archipelago and should address the issues of resettlement, access to the fisheries resources, and the economic development of the islands in a manner which would not prejudice an eventual enjoyment of sovereignty. A total ban on fisheries exploitation and omission of those issues from any MPA project would not be compatible with the longterm resolution of, or progress in the talks, on the sovereignty issue.

The stand of the Government of Mauritius is that the existing framework for talks on the Chagos Archipelago and the related environmental issues should not be overtaken or bypassed by the consultation launched by the British Government on the proposed MPA.¹⁷⁵

On 27 November 2009, the Parties’ respective Prime Ministers, Dr Navinchandra Ramgoolam, GCSK, MP, FRCP and the Rt. Hon. Gordon Brown MP were present at the Commonwealth Heads of Government Meeting ("CHOGM") in Trinidad and Tobago. The Parties agree that the Prime Ministers had a separate discussion regarding the MPA, but disagree as to its contents.

Mauritius’ contemporaneous record of the conversation is as follows:

33. A tete-a-tete meeting took place between the British Prime Minister and myself in the morning of Friday 27 November 2009. Two main subjects were covered:

(a) Mauritian Sovereignty over the Chagos Archipelago; and

(b) the Marine Protected Area.

34. I explained to the British Prime Minister that the bilateral talks which we have engaged with the British side are going on in a positive atmosphere and that it is imperative that the issue of sovereignty continues to be addressed.

35. I stated that Mauritius does not recognize the British Indian Ocean Territory and therefore, we cannot even discuss the issue of a Marine Protected Area with them. I emphasized that the issue of resettlement remains a pending issue and Mauritian fishing rights have to be taken into consideration. I therefore indicated that since bilateral talks were intended to deal with all the issues concerning Chagos progressively, this is the venue we should continue to use to further our discussions.

36. The British Prime Minister paid tribute to the leadership role played by Mauritius in the deliberations of the meeting particularly on the issue of Climate Change from the perspective of Small Island Developing Countries. On the issue of Marine Protected Area, he assured me that nothing would be done to undermine resettlement and the sovereignty claim of Mauritius over the Chagos Archipelago and that he would put a hold on this project.¹⁷⁶

In the present proceedings, Dr Ramgoolam recalls the conversation further in the following terms:

10. [...] I [...] took the opportunity to convey to Mr Brown the deep concern of Mauritius over the proposal of the United Kingdom to establish a 'marine protected area' around the Chagos Archipelago and the launching of a public consultation by the UK Foreign and Commonwealth Office on 10 November 2009, just two weeks earlier, in this regard. That announcement had been the subject of media attention. I indicated to Mr Brown that when the British High Commissioner in Mauritius had called on me on 22 October 2009 to announce the UK’s proposal, I had expressed surprise that he was not able to offer me any document in relation to that proposal and told him that I would raise the matter with the British Prime Minister during the forthcoming CHOGM in Port of Spain. I had made very clear the objection of Mauritius to the UK’s proposal.

11. I also conveyed to Mr Brown that since the bilateral talks between Mauritius and the United Kingdom were intended to deal with all issues relating to the Chagos Archipelago, they were the only proper forum in which there should be further discussions on the proposed 'marine protected area'.

12. I further pointed out that the issues of sovereignty and resettlement remained pending and that the rights of Mauritius in the Chagos Archipelago waters had to be taken into consideration.

13. In response, Mr Brown asked me once again: "What would you like me to do?" I remember these words clearly.

14. I replied: "You must put a stop to it". There could have been no doubt that I was referring to the proposed 'marine protected area'.

15. Mr Brown then said: "I will put it on hold". He told me that he would speak to the British Foreign Secretary. He also assured me that the proposed 'marine protected area' would be discussed only within the framework of the bilateral talks between Mauritius and the UK.¹⁷⁷

The United Kingdom’s account of the same conversation differs. Based on internal United Kingdom correspondence, by 8 December 2009 the British High Commission became aware of Dr Ramgoolam’s understanding of his exchange with Mr Brown and sought clarification from London. The Foreign and Commonwealth Office then approached the Prime Minister’s Office whose account, as relayed, was to the effect that "the PM did not say that the consultation/MPA proposal was over or that the issue had finished. What we are told the PM said is that were Ramgoolam to be haemorrhaging support in the run up to Mauritian elections, then the PM would do what he could to be helpful - this leading in to the question around delaying any decision until after the Mauritian election."¹⁷⁸ As presented in these proceedings, the United Kingdom’s view of this conversation is that "Gordon Brown did not say what the Mauritian Prime Minister understood him to have said".¹⁷⁹

On 15 December 2009, the UK Foreign Secretary, David Miliband, wrote to the Mauritius Foreign Minister, Dr Arvin Boolell, recalling their parallel discussions at the CHOGM:

I very much welcomed the opportunity to meet you at CHOGM. We had a useful discussion on the proposal for a Marine Protected Area in the British Indian Ocean Territory. I believe we both agree that without prejudice to wider political issues, discussed below, there is an opportunity to protect an area of outstanding natural beauty which contains islands, reef systems and waters which in terms of preservation and biodiversity are among the richest on the planet. As we agreed at the time, both the UK and Mauritius now need to reflect on next steps and work to bridge any differences in approach.

At our meeting, you mentioned your concerns that the UK should have consulted Mauritius further before launching the consultation exercise. I regret any difficulty this has caused you or your Prime Minister in Port Louis. I hope you will recognize that we have been open about the plans and that the offer of further talks has been on the table since July.

I would like to reassure you again that the public consultation does not in any way prejudice or cut across our bilateral intergovernmental dialogue with Mauritius on the proposed Marine Protected Area. The purpose of the public consultation is to seek the views of the wider interested community, including scientists, NGOs, those with commercial interests and other stakeholders such as the Chagossians.

The consultations and our plans for an MPA do not in any way impact on our commitment to cede the territory when it is no longer needed for defence purposes. Our ongoing bilateral talks are an excellent forum for your Government to express its views on the MPA. We welcome the prospect of further discussion in the context of these talks, the next round of which now look likely to happen in January.

As well as the MPA there are, of course, many other issues for bilateral discussion. My officials remain ready to continue the talks and I hope that Mauritius will take up the opportunity to pursue this bilateral dialogue.

[...]¹⁸⁰

Dr Boolell responded to the Foreign Secretary on 30 December 2009 as follows:

During our recent meeting in the margins of the Commonwealth Heads of Government Meeting, I had expressed the concerns of the Government of Mauritius about the Marine Protected Area project. I had stated that it was inappropriate for the British authorities to embark on consultations on the matter outside the bilateral Mauritius-United Kingdom mechanism for talks on issues relating to the Chagos Archipelago.

On the substance of the proposal, I had conveyed to you that the Government of Mauritius considers that the establishment of a Marine Protected Area around the Chagos Archipelago should not be incompatible with the sovereignty of Mauritius over the Chagos Archipelago. As you are aware, the Mauritian position, as also endorsed at various multilateral fora, is that the Chagos Archipelago was illegally excised by the British Government from the territory of Mauritius prior to the grant of independence to Mauritius. The Government of Mauritius has repeatedly informed the British Government that it does not recognize the so-called British Indian Ocean Territory and deplores the fact that Mauritius is still not in a position to exercise effective control over the Chagos Archipelago as a result of the illegal excision of its territory.

Moreover, the issues of resettlement in the Chagos Archipelago, access to the fisheries resources and the economic development of the islands in a manner that would not prejudice the effective exercise by Mauritius of its sovereignty over the Chagos Archipelago are matters of high priority to the Government of Mauritius. The exclusion of such important issues in any discussion relating to the proposed establishment of a Marine Protected Area would not be compatible with resolution of the issue of sovereignty over the Chagos Archipelago and progress in the ongoing talks between Mauritius and the United Kingdom.

In these circumstances, as I have mentioned, Mauritius is not in a position to hold separate consultations with the team of experts of the UK on the proposal to establish a Marine Protected Area.

You will no doubt be aware that, in the margins of the last CHOGM, our respective Prime Ministers agreed that the Marine Protected Area project be put on hold and that this issue be addressed during the next round of Mauritius-United Kingdom bilateral talks.¹⁸¹

On the same day, Mauritius dispatched a Note Verbale to the United Kingdom, stating as follows:

The Ministry of Foreign Affairs, Regional Integration and International Trade wishes to inform the Foreign and Commonwealth Office that the Government of Mauritius considers that the next round of bilateral talks between the two Governments cannot take place during the month of January 2010, in the absence of satisfactory clarification and reassurances on the part of the Government of the United Kingdom on issues raised by the Government of Mauritius in the above-mentioned Note Verbale [of 23 November 2009] in relation to the Marine Protected Area project and in view of the continuation by the Government of the United Kingdom of the initial consultation process it had embarked upon.

The Government of Mauritius trusts that it will receive, within a reasonable period, adequate clarification and reassurances on the part of the Government of the United Kingdom on the issues raised in the above-mentioned Note Verbale.¹⁸²

On 13 January 2010, Foreign Minister Boolell called on the British High Commissioner, Mr John Murton. The conversation that ensued covered the differing understandings of the Prime Ministers’ meeting at CHOGM and potential ways forward. The High Commissioner’s record is as follows:

By far the biggest issue was the outcome of the PM Brown/PM Ramgoolam tete-a-tete. Ramgoolam had briefed Cabinet following the meeting at CHOGM and told them that Brown had agreed to 'drop' the consultation. He was very (and unusually) clear and definitive about this and had clearly expected Brown to make some sort of statement to this effect. Ramgoolam also briefed the press on the matter and took pride in pointing to this result as stemming from his good relationship with Brown (Boolell noted he had a 'soft spot' for him). As the days wore on after the summit without a statement, Ramgoolam became increasingly frustrated. When Miliband’s letter arrived (which we had written thinking it was very conciliatory), Ramgoolam took this as a kick in the teeth. Ramgoolam’s anger triggered the notes of 30 December and, upon Ramgoolam’s instructions, the press briefing by Boolell earlier this month.

Some of these points are manageable, but the discord between Ramgoolam’s readout of the PM’s meeting and the readout from Brown is clearly large and, in many ways, insurmountable. I detected no sense that the Mauritians are playing a game on this. Ramgoolam clearly believes Brown promised him what he had wanted and that, somehow, Miliband has sought to circumvent this. I assured Boolell this wasn't the case and showed him the readout we had received from No 10. We both scratched our heads.

I noted we needed a way forward that allowed the MPA consultation to continue and ensured that the issue did not become a political burden to the Government here. I passed across the draft letter I had shared with you yesterday and explained that, if we sent such a letter, a conciliatory reply from the Mauritians would go a long way to resolving things. Boolell suggested a number of changes to the letter.¹⁸³

On 20 January 2010, the British High Commissioner met with Prime Minister Ramgoolam on the subject of the MPA consultations. The United Kingdom’s record of this conversation is, in relevant part, as follows:

PM Ramgoolam reiterated his record of the bilateral with Gordon Brown: Brown had been 'very thankful' for all Ramgoolam had done sorting out the CHOGM Summit impasse with Sri Lanka - enabling Sri Lanka to climb down without being humiliated. When Ramgoolam had begun setting out his case on BIOT, Brown had 'interrupted' him to say 'Navin, what do you want?'. Ramgoolam says he had asked for the MPA consultation to be stopped, and Brown had agreed: "It’s done." Hence Mauritius’ upset when David Miliband’s letter of 15 December indicated the consultation was ongoing.

I went through our version of events and explained the readout we had received from the meeting. I noted that, although I obviously hadn't been present, I knew and trusted the PM’s [Private Secretary]. In light of the readout we'd received, David Miliband’s letter was written in good faith as a constructive gesture. We'd been stung by the reaction it had met, particularly by the mis-reporting of Boolell’s comments in the press and the claim we'd been 'dishonest'. Discussions with Koonjul and Boolell had revealed that the MFA here hadn't been fully aware of the extent of consultations we'd had with Ramgoolam himself, and this had (wrongly) coloured their advice to the PM. Mauritian non-participation at recent seminars wasn't helpful; they could easily have taken part under some form of disclaimer on sovereignty. More willingness to engage from them could have dispelled a lot of misunderstanding. He took these points.

Looking forward, I explained how my goal in meeting the PM was to enable both sides to move forward without humiliation and to avoid any further painting-into-corners. Ramgoolam jumped in: should he write to Gordon Brown to clarify the outcome of the CHOGM meeting? I sought to deflect him from this: for such a move not to backfire, the PM would have to be sure that he'd get the answer he wanted from Gordon Brown - there were political issues in the mix in the UK too. Was he sure this would work? Ramgoolam pondered aloud about what he perceived as David Miliband’s strong commitment to the MPA and whether recent political events in the UK might inhibit Gordon Brown from pushing Miliband to rein in the consultation, even if he'd wanted to.

I noted that I had been working with Boolell to draft a letter that might help both sides move forward. Boolell was keen for the PM to see it. I didn't want to send the letter until I knew it would help the situation. The draft answered all of Mauritius’ concerns re consultation with [the Government of Mauritius] taking place through bilateral talks, sovereignty, non-prejudice to settlement case at ECHR etc. Ramgoolam undertook to look at it with Ruhee. He was glad no other copies existed yet.

[...]

I followed up afterwards by telephone with Ruhee, principally to alert him to the [Public Consultation] facilitator’s impending arrival (there hadn't been a good moment to raise this in the meeting). We'd need to factor a line on this into the letter to clear the way for her to come without it becoming a politically exploitable issue here.¹⁸⁴

On 4 February 2010, Mauritius submitted written evidence to the UK House of Commons Select Committee on Foreign Affairs in respect of the MPA:

2. Since there is an on-going bilateral Mauritius-UK mechanism for talks and consultations on issues relating to the Chagos Archipelago, it is inappropriate and insulting for the British Government to pursue consultations globally on the proposal for the establishment of an MPA around the Chagos Archipelago outside this bilateral framework. This position was brought to the attention of the British Government by way of Note Verbale dated 23 November 2009 issued by the Ministry of Foreign Affairs, Regional Integration and International Trade of the Republic of Mauritius to the UK Foreign and Commonwealth Office. We have not received any answer yet whilst the FCO continues to defy our deep concerns on this process.

3. The manner in which the Marine Protected Area proposal is being dealt with makes us feel that it is being imposed on Mauritius with a predetermined agenda.

4. The establishment of an MPA around the Chagos Archipelago must be compatible with the sovereignty of Mauritius over the Chagos Archipelago. Any endorsement of the proposed unilateral initiative of the FCO's, particularly in some scientific quarters, would be tantamount to condoning the violation of international law and the enduring human tragedy.

5. Moreover, the issue of resettlement in the Chagos Archipelago, access to the fisheries resources, and the economic development of the islands in a manner which would not prejudice the effective exercise by Mauritius of its sovereignty over the Chagos Archipelago are matters of high priority to the Government of Mauritius.

6. The exclusion of such important issues from any MPA project and a total ban on fisheries exploitation would not be compatible with resolution of the issue of sovereignty over the Chagos Archipelago and progress in the ongoing talks between Mauritius and the United Kingdom.

7. The existing framework of talks between Mauritius and the UK on the Chagos Archipelago and the related environmental issues should not be overtaken or bypassed by the public consultation launched by the British Government on the proposed establishment of an MPA around the Chagos Archipelago.

8. The establishment of any MPA around the Chagos Archipelago should also address the benefits that Mauritius should derive from any mineral or oil that may be discovered in or near Chagos Archipelago (as per the undertaking given in 1965).¹⁸⁵

On 8 February 2010, the British High Commissioner met again with Foreign Minister Boolell on the subject of the MPA. The United Kingdom’s record of this conversation is, in relevant part, as follows:

Much of the time was spent covering old ground, including [Government of Mauritius] unhappiness with the way the consultation was launched and the divergent readouts from the PM-PM meeting at CHOGM. We noted that repeated media briefing from the Mauritian side was unhelpful (e.g. Saturday’s Mauricien).

Boolell raised the issue of Chagossian resettlement and the meaning of our 'without prejudice' phrase in the MPA consultation document. We noted it meant respect for the [European Court of Human Rights] judgement. We then sought to unpick the issue of resettlement from the MPA, underlining once more the risks that resettlement potentially posed to our commitment to cede the islands when no longer needed for defence purposes. There was considerable discussion of the role of the Chagossian community in this process.

[...]

In discussing the way forward from here, Boolell suggested that we meet with Cabinet Secretary Seebaluck [ sic ] to request bilateral talks. We might do so using a 'short' letter: our earlier draft had been too 'long' and 'open to misinterpretation'. Once the 12th February [the originally scheduled end of the Public Consultation] was past, the atmosphere would be 'conducive' and 'welcoming' to a new round of talks. We alluded to the fact that we might not find it easy to draw a line under the consultation without some form of engagement with the Chagossians, noting that some argued there was a requirement to engage fully even with those not able to respond to a written consultation process.

It was clear that the Mauritians would not welcome the visit of the facilitator. Boolell noted that a visit would be a 'slight' on the people and Government of Mauritius. They wanted to retain their 'sovereign rights'. We asked if a [video teleconference]-based consultation be easier [ sic ] for the Mauritians to swallow? Boolell could only agree to take note of this and consider the matter, but didn't commit.

We said that, if talks could be restarted (and we'd been waiting for the Mauritians to discuss dates since 22 January), they'd be productive only if Mauritius came with a clear sense of what it realistically wanted rather than either (a) demanding sovereignty as they had done in London or (b) dwelling only on those things that were unacceptable to Mauritius. It would be best to focus on areas of common ground and potential cooperation. The idea of an MPA provided areas for joint work - the Mauritian Finance Minister had set aside money for MPAs in his recent budget. We thought there was enough common ground for this to be a constructive area.

Boolell took the point and raised a couple of issues that could be profitably discussed:

• demarcation of the continental shelf;

• the terminology 'MPA'. Marine Protected Area gave the idea of 'ownership' and the UK 'protecting' its sovereignty claim. Conservation/Preservation were better words, or at least 'the protection of the marine environment'. Mauritius was increasingly recognising it was an 'Oceanic state' and cooperation around this sphere could be helpful.

• future PM-PM engagement;

• trilateral discussions with the US [we countered this wasn't within our gift]

• a rest from nuclear ships visiting DG (just to give some political space at home in Mauritius)¹⁸⁶

On 15 February 2010, the United Kingdom wrote to Mauritius, referencing the latter’s Note Verbale of 30 December 2009 and enquiring only as to "an indication as to when the Government of Mauritius would be willing to reschedule such a meeting: either in London or Port Louis."¹⁸⁷ The Secretary to the Cabinet of Mauritius, Mr Seeballuck, responded on 19 February 2010, referencing the CHOGM discussion and stating:

3. I wish to reiterate the position of the Government of Mauritius to the effect that the consultation process on the proposed MPA should be stopped and the current Consultation Paper, which is unilateral and prejudicial to the interests of Mauritius withdrawn. Indeed, the Consultation Paper is a unilateral UK initiative which ignores the agreed principles and spirit of the ongoing Mauritius-UK bilateral talks and constitutes a serious setback to progress in these talks.

4. I further wish to inform you that the Government of Mauritius insists that any proposal for the protection of the marine environment in the Chagos Archipelago area needs to be compatible with and meaningfully take on board the position of Mauritius on the sovereignty over the Chagos Archipelago and address the issues of resettlement and access by Mauritians to fisheries resources in that area.

5. I also wish to state that the Government of Mauritius is keen to resume the bilateral talks on the premises outlined above.¹⁸⁸

On 19 March 2010, the British High Commission responded to Mauritius’ Note of 15 February 2010, reiterating the United Kingdom’s views on sovereignty over the Archipelago and on resettlement, and stating with respect to the MPA Public Consultation as follows:

The United Kingdom should like to reiterate that no decision on the creation of an MPA has yet been taken. However, as stated previously in discussions between Ministers and Officials and set out clearly in the MPA consultation document, the establishment of any marine protected area will have no impact on the United Kingdom’s commitment to cede the Territory to Mauritius when it is no longer needed for defence purposes. Additionally, the United Kingdom is keen to continue dialogue about environmental protection within bilateral framework or separately. The public consultation does not preclude, overtake or bypass these talks.¹⁸⁹

The High Commissioner further stated that "[l]ike Mauritius, the UK is keen to continue these bilateral talks as there are many other things we can discuss with regards to BIOT."¹⁹⁰

The Public Consultation ran until 5 March 2010. Thereafter, the Foreign Secretary received a detailed report from the consultation facilitator summarizing the consultation process and the comments received. The summary of the facilitator’s report presented the consultation as follows:

[...]

6. The response was wide ranging, with a global reach. It included inputs from private individuals, academic and scientific institutions, environmental organisations and networks, fishing and yachting interests, members of the Chagossian community, British MPs and peers and representatives of other governments.

7. The great majority of respondents - well over 90% - made clear that they supported greater marine protection of some sort in the Chagos Archipelago in principle. However, views on this proposal were more mixed, covering a wide spectrum of views. Responses did not confine themselves to the options listed in the Consultation Document.

8. The main difference between the responses was their view on potential resettlement of members of the Chagossian community, and whether this question should be tackled before designation of any MPA, or whether changes could be made later if circumstances changed, in an MPA agreed, as the Consultation Document suggests, in the context of the Government’s policy on the Territory, without prejudice to ongoing legal proceedings.

9. Of those who supported one of the three listed options the great majority supported Option 1, a full no-take marine reserve for the whole of the territorial waters and Environmental Preservation and Protection Zone (EPPZ)/Fisheries Conservation and Management Zone (FCMZ). The reasons given were generally very much in line with the conservation, climate change and scientific benefits set out in the Consultation Document. A number also highlighted a legacy element, as well as the opportunity to show leadership and provide an example for others, while contributing to meeting a number of global environmental commitments.

10. In terms of numbers, support for options 2 and 3 was limited. However, they were universally the choice of the Indian Ocean commercial tuna fishing community, as well as a number of regional interests. While agreeing that there was a strong case for protecting the fragile reef environment, this group considered that the scientific case for the extra benefits of option 1 was not strongly demonstrated and the group did not want to see a negative economic impact on the tuna industry. In addition, a limited number of private individuals thought that controlled, licensed fishing at around the current level was sufficient protection and was not causing significant decline or degradation.

11. A significant body of response did not support proceeding with any of the three listed options at the current time. Of this group, some, including most but not all of the Chagossian community, argued simply for abandoning or postponing the current proposal until further consultation and agreement could take place, while others proposed one or another different option (a 'fourth option'), which sought to take account of Chagossian (and in some cases other regional) requirements.

12. As well as their headline comments on preferred options, respondents raised a number of issues of interest or concern to them. These included: the consultation process itself; the rights and interests of the Chagossian community; regional interests and concerns; enforcement of an MPA; costs associated with an MPA; yachting interests; piracy; Diego Garcia and the US base; bycatch from commercial fishing, including sharks and fragile species; fish stocks; reputational issues; and other proposed environmental measures. These are described in more detail in a final section which summarises the issues covered in responses received to each of the Consultation questions.¹⁹¹

The United Kingdom’s further decision-making with respect to the MPA was then marked by significant differences between the political and diplomatic/civil service level. On 30 March 2010, the BIOT Administrator made a submission to the Parliamentary Under Secretary and Foreign Secretary entitled "British Indian Ocean Territory (BIOT): Proposed Marine Protected Area (MPA): Next Steps". Summarizing relevant considerations, including vis-a-vis Mauritius, the submission recommended as follows:

Preferred options

That the Foreign Secretary announces the publication of the report on the responses to the FCO public consultation into whether to create an MPA in the Territory; commenting on the level of interest in the consultation and general support for environmental protection and for a no-take fishing zone; noting that the consultation has thrown up a range of views which need to be explored further; stating that he believes that the establishment of an MPA is the way ahead for the protection of the environment of the Territory and that he will ask officials to work towards this. But he should stop short of announcing that he is going to ask the BIOT Commissioner to declare an MPA in the Territory at this stage. I attach a draft statement which could be used as both as a press statement and as a Written Ministerial Statement.¹⁹²

After receiving an indication that the Foreign Secretary was contemplating moving ahead directly with the declaration of the MPA, the BIOT Commissioner and BIOT Administrator exchanged correspondence with the British High Commissioner in Mauritius regarding the likely Mauritian reaction to such action. In the course of internal correspondence, the British High Commissioner stated his view that "to declare the MPA today could have very significant negative consequences for the bilateral relationship. It would be seen by the Government here in general, and by PM Ramgoolam in particular, as exceedingly damaging timing."¹⁹³ Reacting to this concern, on 31 March 2010, the BIOT Administrator provided a further minute to the Foreign Secretary as follows:

1. The FS has said that, in an ideal world, he would like to declare an MPA in BIOT and spend 3 months reaching some sort of agreement with the Mauritian government on the governance of the area but making it clear that we will have 3 months to consult them but if they won't come to an agreement, we will go ahead without them. You have asked for options, whether this is feasible and possible implications. We have discussed this with our High Commissioner in Port Louis.

2. The "3 months", or any defined period, to hammer out details of some sort of management structure will not fly in Mauritius. Ramgoolam would not be able to commit to negotiating in this framework if an MPA had already been declared. Any such offer would be seen as forcing them into a position and would only antagonize them further.

3. What might work in Mauritius is the announcement as suggested in my submission of 30 March. Our High Commissioner thinks that there might be a market for a proposal to work with Mauritius as a privileged partner on management issues but this would need to be done prior to a final decision and such talks would have to precede any formal announcement of an MPA. If Mauritius were not prepared to engage in any sensible way, we would want to press on without them, but we would want to give them time to reflect and ourselves time to manage the negative consequences.

4. The High Commissioner has asked that the Foreign Secretary be made aware that the timing could not be worse locally than to declare a full no-take MPA today. The Parliamentary Labour Party of Mauritius is currently in a closed door meeting and it is expected that they will announce their own elections during the course of today. All Ministers are uncontactable and so the High Commission have no capacity to manage political reactions. He also wanted to point out that declaring an MPA today could have very significant negative consequences for the bilateral relationship. It would be seen, especially by Ramgoolam, as exceedingly damaging timing and pressure would be on for him to commit to taking legal action to challenge the establishment of an MPA. The Foreign Secretary will recall the atmospherics of his telephone conversation with Ramgoolam on the day the consultation was launched.¹⁹⁴

On 31 March 2010, the Private Secretary to the Foreign Secretary wrote to the BIOT Administrator, conveying the following decision:

The Foreign Secretary was grateful for your submission and the copy of the report on the consultations. He has carefully considered the arguments in the submission and the views expressed during the consultation. He was grateful for your further note today. He has considered the submission in light of the High Commissioner’s views and has given serious thought to the different possible options for announcing an MPA.

The Foreign Secretary has decided to instruct Colin Roberts [the BIOT Commissioner] to declare the full MPA (option one) on 1 April. There will then need to be an announcement to this effect.

I would be grateful if you could take forward both.¹⁹⁵

On 1 April 2010, the BIOT Commissioner issued Proclamation No. 1 of 2010, formally establishing the MPA.¹⁹⁶ Before the Proclamation was made public, the UK Foreign Secretary placed a call to the Prime Minister of Mauritius. According to the United Kingdom FCO’s minute of the call:

1. The Foreign Secretary said that he wanted to inform the Mauritius Prime Minister that he would today instruct the BIOT Commissioner to establish a Marine Protected Area (MPA) in the British Indian Ocean Territory. We were telling the Prime Minister this in advance as we did not want there to be any surprises.

2. The Foreign Secretary said that both the UK and Mauritius were commited [ sic ] to the environmental agenda and the establishment of the MPA had no impact on the UK commitment to cede BIOT to Mauritius when the territory was no longer needed for defence purposes. Nor would it prejudice the legal position of Mauritius or the Chagos Islanders. The UK valued the relationship with Mauritius and the Foreign Secretary hoped that we could cooperate together to ensure that the MPA was a success.

3. The Foreign Secretary said there had been a very large response to the consultation exercise with about a quarter of a million responses. This was a remarkable number. The majority of the responses were straightforward but there had also been responses from the environmental, political, governmental and scientific communities and some from the business community. The consultation showed that those arguing for commercial exploitation of the area were clearly in the minority. There had been some debate around the no-take approach and there was overwhelming support for that.

4. Ramgoolam said that he was disappointed that there had not been bilateral discussions. He asked if it might be possible to delay the announcement until after the Mauritius elections. It was a controversial issue in Mauritius. The Foreign Secretary said that the consultation had been thorough and there had already been an extension to the consultation period. It would not be possible to delay the announcement. The UK would stress that the decision was without prejudice to the legal position of the Chagos Islanders or to the discussions with Mauritius on the Territory.

5. The Foreign Secretary said he would say very clearly that we would work with all interested parties, in Britain and internationally, on the implementation of the notake approach. He would also make clear that our commitment to the government and people of Mauritius in respect of ceding sovereignty at the appropriate time was strong and clear. While recognising the disagreement with the Mauritius Government on the process leading up to the establishment of the MPA, he hoped that this could bring the two governments together to work in the best interests of the environment.

6. Ramgoolam said that he had to take the line that Mauritius disagreed with the decision on the MPA but he would like to say that he and the Foreign Secretary had talked about sovereignty. The Foreign Secretary stressed that the sovereignty issue had not changed and Ramgoolam should not seek to suggest that was the purpose of the phone call. If it would help, Ramgoolam could say that if both governments were re-elected then there could be early bilateral talks on the implementation of the MPA.

7. Ramgoolam said that when the Mauritians tried to talk to the United States about BIOT the Americans took the line that Mauritius needed to settle the sovereignty issue with the UK first. The Foreign Secretary said that our position was clear. We would cede the Territory to Mauritius when we no longer required the base.¹⁹⁷

On 2 April 2010, Mauritius protested against the declaration of the MPA in the following terms:

The Government of the Republic of Mauritius strongly objects to the decision of the British Government to create a marine protected area (MPA) around the Chagos Archipelago, as announced by UK Secretary of State for Foreign and Commonwealth Affairs David Miliband yesterday.

The Government of the Republic of Mauritius wishes to recall that on several occasions following the announcement by the British authorities for an international consultation on their proposal for the creation of an MPA in the waters of the Chagos Archipelago, the Government of Mauritius conveyed its strong opposition to such a project being undertaken without consultation with and the consent of the Government of the Republic of Mauritius. In this regard, the Ministry refers to its Notes Verbales No. 1197/28/10 dated 23 November 2009 and No. 1197/28/4 dated 30 December 2009 in particular. The position of the Government of Mauritius was also conveyed directly by the Prime Minister of Mauritius to British Prime Minister Gordon Brown during the Commonwealth Heads of Government Meeting (CHOGM) in Port of Spain last November and earlier to British Foreign Secretary David Miliband over the phone. The Minister of Foreign Affairs, Regional Integration and International Trade of Mauritius, Dr. the Hon. Arvin Boolell, also communicated the position of Mauritius to Foreign Secretary Miliband during CHOGM in Port of Spain and to the British High Commissioner at several meetings.

It was explained in very clear terms during the above-mentioned meetings that Mauritius does not recognize the so-called British Indian Ocean Territory and that the Chagos Archipelago, including Diego Garcia, forms an integral part of the sovereign territory of Mauritius both under our national law and international law. It was also mentioned that the Chagos Archipelago, including Diego Garcia, was illegally excised from Mauritius by the British Government prior to grant of independence in violation of United Nations General Assembly resolutions 1514 (XV) of 14 December 1960 and 2066 (XX) of 16 December 1965.

The Government of the Republic of Mauritius further believes that the creation of an MPA at this stage is inconsistent with the right of settlement in the Chagos Archipelago of Mauritians, including the right of return of Mauritians of Chagossian origin which presently is under consideration by the European Court of Human Rights following a representation made by Mauritians of Chagossian origin.

The Government of the Republic of Mauritius will not recognize the existence of the marine protected area in case it is established and will look into legal and other options that are now open to it. The more so, the Anglo-US Lease Agreement in respect of the Chagos Archipelago, concluded in breach of the sovereignty rights of Mauritius over the Chagos Archipelago, is about to expire in 2016 and the Chagos Archipelago, including Diego Garcia, should be effectively returned to Mauritius at the expiry of the Agreement.¹⁹⁸

On 6 April 2010, the United Kingdom declared a general election. In response to a question posed during the hearing regarding the speed with which the decision to declare the MPA was taken, the United Kingdom noted as follows:

there was an election due at the beginning of May, which was a little over four weeks later. In the British system of government, when an election is called, essentially government stops. No new policies can be introduced. So, either Mr. Miliband took his decision on 1 April—which is the last possible date he could do so before the election —or he could leave the decision for the incoming government four weeks later. He took the decision, he did lose office, a new government came in, and they confirmed his decision.¹⁹⁹

On 3 June 2010, Prime Minister Ramgoolam raised the issue of the MPA declaration during a meeting with the new UK Foreign Secretary, William Hague.²⁰⁰

On 1 September 2010, the BIOT Administrator made a submission to the Foreign Secretary regarding the implementation and financing of the MPA. This submission recounted the United Kingdom’s analysis of the Mauritian attitude to the MPA in the following terms:

9. At his meeting with Prime Minister Ramgoolam on 3 June, the Foreign Secretary advised that he would familiarise himself with the issues surrounding the MPA but would not raise Ramgoolam’s hopes. He stressed that he could not give Ramgoolam any reason to hope for a change in policy but that he and Mr Bellingham did want to work closely with Ramgoolam and his government. Mr Bellingham repeated these messages when he met Foreign Minister Boolell at the AU Summit on 22 July 2010. The Acting High Commissioner in Port Louis has also recently informed Foreign Minister Boolell of the Minister for Africa’s letters to Lord Luce and Olivier Bancoult. However, the Mauritians are likely still to be disappointed: they had high hopes for the new Government. This issue is likely to continue to cause tension in our otherwise good bilateral relations with Mauritius, and could impact on our wider bilateral objectives, including working with Mauritius on counter piracy in the Indian Ocean.

10. The decision to continue with the MPA of itself is unlikely to push Mauritius to seek an Advisory Opinion at the International Court of Justice. But Boolell warned the Acting High Commissioner in Port Louis on 23 August that they would be prepared to do so if there were no progress on sovereignty. They would also seek compensation for income accrued over the period of time which the "UK had denied them their rights over the Territory". While we are confident in the strength of our legal case, a decision by Mauritius to challenge our position on sovereignty would be awkward. We will need to develop an active approach to Mauritius, therefore, being clear about our red lines, but being positive about bilateral talks and options for an advisory role in the implementation of the MPA. This might include options, such as offering Mauritius a "privileged partnership" where Mauritius could play an advisory role in the management of the MPA, which does not impact on the sovereignty position. While we are not obliged to offer Mauritius this, it might help to bring them along with us on the issue. We expect the new High Commissioner to have opportunities to take stock of Mauritian thinking in his introductory meetings.

11. There is a slim chance that Mauritius may raise the issue of their historical fishing rights in the Territory. During negotiations over the excision of the Chagos Archipelago between Mauritius and the UK in 1965, the UK gave an undertaking that HMG would use their good offices with the US government to ensure that certain facilities including fishing rights in Chagos would remain available "as far as was practicable". Over the years, these rights have come to mean free fishing licences to Mauritian-flagged vessels upon application. In our exchanges on the MPA to date the Mauritians have never raised the question of fishing rights. This may be because they see it as inconsistent with their sovereignty claim. Mauritius has shown interest only in trying to secure a percentage of the fishing licence money generated by the Territory’s fisheries. They do not accept our figures which show that the fishery operates at a substantial loss. Very few Mauritian-flagged vessels have fished in the Territory’s Fishing (Conservation and Management) Zone. Only a couple of Mauritian-flagged vessels are run by Chagossians and their "rights" are being taken up in the Judicial Review into the MPA case being brought by Clifford Chance against the Secretary of State.²⁰¹

On 9 September 2010, the new British High Commissioner in Mauritius, Mr Nicholas Leake, met with the then President of Mauritius, the Rt. Hon. Sir Anerood Jugnauth KCMG QC GCSK PC,²⁰² Prime Minister Ramgoolam, and Foreign Minister Boolell while presenting his credentials. The High Commissioner’s account of that conversation is as follows:

[...] The talks were wide-ranging, and other bilateral points will be reported separately to Africa Directorate. However, they all took the opportunity to raise Chagos/BIOT, which remains an irritant following the decision to establish a Marine Protection Area (MPA) in BIOT.

2. [President] Jugnauth said that he understood that the UK position was that sovereignty would be ceded to Mauritius once Diego Garcia was no longer needed for military purposes. But Mauritius had always understood that this meant the Cold War. The Cold War was now over, so was Diego Garcia still needed for military purposes? And if so, would there not always be a reason why the island was still needed? Jugnauth later added that the UK should just hand back the Territory; Mauritius had no problem with the US continuing to use the base, but they should pay rent to Mauritius.

3. Prime Minister Ramgoolam said that he appreciated you seeing him at Carlton Gardens on his recent visit to London. He rehearsed his disappointment following his CHOGM meeting with Gordon Brown, where he felt he had been promised that the MPA would be put on hold. But he was in "more sorrow than anger" mode. I said that we did not want to raise any hopes of a change of policy. The UK recognised the Mauritian position on sovereignty, and we trusted that the Mauritians understood ours. But, aside from sovereignty, there were a number of issues which could be discussed, and we hoped for a resumption of bilateral talks. The excellent and important relationship between the two countries should allow constructive discussions. You would be writing to set out the position. Ramgoolam said he would wait for the letter before considering his next move, but if there was no progress he would "have to do something".

4. Foreign Minister Boolell was grateful that Mr Bellingham had met him in Kampala at the recent [AU] summit. On BIOT, he said that the MPA consultation had marred the relationship, but if there was a will we could make progress. Mauritius was keen to restart bilateral talks, but 2014 was just around the corner and this was an important date under the UK/US agreement. They would like more clarity on this -the Government was under increasing pressure "from African Union friends" to take action ahead of that date. Boolell also mentioned Mauritius’ responsibilities under the Pelindaba Treaty (which says that there should be no nuclear weapons on the territory of AU members).

5. Boolell recognised that the US base was here to stay, but Mauritius wanted to exercise its "legitimate rights" over the territory. They wanted to be part of any discussions, and were unhappy that the US refused to engage with them and kept telling them to discuss all BIOT issues with us. Boolell drew attention to the Chagossian case in the ECHR, and said that this was a rare case where the Mauritian government and opposition were united. He also hinted at "mobilising world opinion", an ICJ case, and seeking "compensation for lost revenue" since independence.²⁰³

Mauritius’ final submissions are as follows:

On the basis of the facts and legal arguments presented in its Memorial, Reply, and during the oral hearings, Mauritius respectfully requests the Arbitral Tribunal to adjudge and declare, in accordance with the provisions of the 1982 United Nations Convention on the Law of the Sea ("the Convention"), in respect of the Chagos Archipelago, that:

(1) the United Kingdom is not entitled to declare an "MPA" or other maritime zones because it is not the "coastal State" within the meaning of inter alia Articles 2, 55, 56 and 76 of the Convention; and/or

(2) having regard to the commitments that it has made to Mauritius in relation to the Chagos Archipelago, the United Kingdom is not entitled unilaterally to declare an "MPA" or other maritime zones because Mauritius has rights as a "coastal State" within the meaning of inter alia Articles 56(1)(b)(iii) and 76(8) of the Convention; and/or

(3) the United Kingdom shall take no steps that may prevent the Commission on the Limits of the Continental Shelf from making recommendations to Mauritius in respect of any full submission that Mauritius may make to the Commission regarding the Chagos Archipelago under Article 76 of the Convention;

(4) The United Kingdom’s purported "MPA" is incompatible with the substantive and procedural obligations of the United Kingdom under the Convention, including inter alia Articles 2, 55, 56, 63, 64, 194 and 300, as well as Article 7 of the Agreement for the Implementation of the Provisions of the United Nations Convention on the Law of the Sea of 10 December 1982 Relating to the Conservation and Management of Straddling Fish Stocks and Highly Migratory Fish Stocks of 4 August 1995.

The United Kingdom’s final submissions are as follows:

For the reasons set out in the Counter-Memorial, the Rejoinder and these oral pleadings, the United Kingdom of Great Britain and Northern Ireland respectfully requests the Tribunal:

(i) to find that it is without jurisdiction over each of the claims of Mauritius;

(ii) in the alternative, to dismiss the claims of Mauritius.

In addition, the United Kingdom of Great Britain and Northern Ireland requests the Tribunal to determine that the costs incurred by the United Kingdom in presenting its case shall be borne by Mauritius, and that Mauritius shall reimburse the United Kingdom for its share of the expenses of the Tribunal.

The United Kingdom objects to the Tribunal’s jurisdiction to consider the claims arising in respect of each of Mauritius’ four final submissions. The United Kingdom also contends that Mauritius has failed, in respect of each of its submissions, to meet the procedural requirement in Article 283 to exchange views regarding the settlement of the Parties’ dispute. Mauritius, in turn, contends that the Tribunal has jurisdiction to consider each of its claims and that the procedural conditions to exercising this jurisdiction have been met.

Set out in brief, the Parties’ differing views on the Tribunal’s jurisdiction reflect their differing interpretations of the dispute settlement provisions of Part XV of the Convention. Mauritius considers that the United Kingdom bears the burden of establishing that an express exception to the Tribunal’s jurisdiction, such as those set out in Articles 297 and 298, is applicable. The United Kingdom, in contrast, considers these proceedings to be an attempt to "stretch the jurisdiction of courts and tribunals under Part XV" beyond permissible boundaries.²⁰⁴ The United Kingdom believes that the Tribunal must instead focus on the "carefully negotiated preconditions, limitations and exceptions" contained in the Convention²⁰⁵ and that so doing will lead the Tribunal to uphold the United Kingdom’s objections.

In approaching the question of its jurisdiction, the Tribunal will first consider its jurisdiction with respect to Mauritius’ First and Second Submissions. Although addressed by the United Kingdom collectively, the Tribunal considers it appropriate to address Mauritius’ First and Second Submissions separately and in turn. The Tribunal will then go on to consider its jurisdiction with respect to Mauritius’ Fourth Submission and the question of the compatibility of the MPA with the Convention. Thereafter, the Tribunal will address its jurisdiction with respect to Mauritius’ Third Submission concerning submission to the CLCS. Finally, the Tribunal will proceed to examine whether Mauritius has met the requirements of Article 283 with respect to those submissions over which the Tribunal would otherwise have jurisdiction.

In its First Submission, Mauritius requests the Tribunal to adjudge and declare that -

(1) the United Kingdom is not entitled to declare an "MPA" or other maritime zones because it is not the "coastal State" within the meaning of inter alia Articles 2, 55, 56 and 76 of the Convention; and/or

[...]

The United Kingdom maintains that the Tribunal lacks jurisdiction over Mauritius’ First Submission, which it characterizes as Mauritius’ "sovereignty claim". According to the United Kingdom, sovereignty over the Chagos Archipelago constitutes "the real issue in the case"²⁰⁶ and is a matter that falls outside the dispute settlement provisions of the Convention. Mauritius, in contrast, submits that "there are no grounds for determining that any aspect of the dispute is beyond the Tribunal’s jurisdiction, based on an ordinary interpretation of the Convention."²⁰⁷

The Parties’ arguments in respect of this objection divide broadly into those concerning the scope of jurisdiction under Articles 286 and 288 of the Convention, the relevance of Article 293 concerning the applicable law, the background understanding of the drafters of the Convention with respect to jurisdiction over land sovereignty issues, and the implications of accepting or rejecting jurisdiction in the present proceedings. Each issue is addressed in turn in the sections that follow.

Articles 286 and 288 of the Convention condition recourse to, and the jurisdiction of, a court or tribunal pursuant to the compulsory procedures entailing binding decisions set out in section 2 of Part XV of the Convention.

Article 288 provides for the Tribunal’s jurisdiction in the following terms:

Article 288 Jurisdiction

1. A court or tribunal referred to in article 287 shall have jurisdiction over any dispute concerning the interpretation or application of this Convention which is submitted to it in accordance with this Part.

2. A court or tribunal referred to in article 287 shall also have jurisdiction over any dispute concerning the interpretation or application of an international agreement related to the purposes of this Convention, which is submitted to it in accordance with the agreement.

[...]

Article 286 links the Tribunal’s compulsory jurisdiction with the non-binding mechanisms for the settlement of disputes, set out in section 1 of Part XV, as follows:

Article 286

Application of procedures under this section

Subject to section 3, any dispute concerning the interpretation or application of this Convention shall, where no settlement has been reached by recourse to section 1, be submitted at the request of any party to the dispute to the court or tribunal having jurisdiction under this section.

Within Part XV, the United Kingdom notes, Articles 286 and 288 of the Convention permit recourse to compulsory settlement, but are subject to "carefully negotiated preconditions, limitations and exceptions."²⁰⁸ Article 286 applies only where "no settlement has been reached by recourse to section 1" and only subject to the limitations and exceptions specified in section 3. The United Kingdom emphasizes that "the obligation to accept compulsory procedures entailing binding decisions applies only to disputes 'concerning the interpretation or application of this Convention'."²⁰⁹ That this provision was intended to restrain the Tribunal’s jurisdiction is, in the United Kingdom’s view, implicit from Article 288(2). That provision extends jurisdiction over related agreements that expressly refer disputes to Part XV of the Convention, but only to the extent that such an agreement is "related to the purposes of this Convention".²¹⁰ Because the possibility of jurisdiction over expressly related agreements is constrained, jurisdiction over disputes which fall to be decided under agreements unrelated to the Convention or under customary international law must also be constrained. According to the United Kingdom, the same conclusion follows from the context of the carefully constructed exclusions to jurisdiction set out in Article 297.²¹¹ As a result of the ordinary meaning of Article 288, the United Kingdom submits that "[d]isputes concerning matters that are wholly exterior to the Convention do not fall within Article 288(1), and that result cannot be avoided by presenting matters as a dispute over who is the coastal State."²¹²

The United Kingdom objects to the Tribunal’s jurisdiction on the grounds that questions of sovereignty lie "at the heart of the current claim"²¹³ and that it is "self-evident... that a dispute concerning sovereignty over land territory is not a dispute concerning the interpretation or application of the law of the sea convention".²¹⁴

"Part XV of the Convention," the United Kingdom recalls, "is not a General Act for the Pacific Settlement of International Disputes."²¹⁵ While some courts and tribunals applying the Convention may have exercised a broader jurisdiction, they have done so only in cases where their jurisdiction arose (as in Peru v. Chile before the International Court of Justice (the "ICJ") (Maritime Dispute (Peru v. Chile), Judgment of 27 January 2014)) from other instruments such as the Pact of Bogotá that provide for the settlement of disputes in terms that are notably broader than those of the Convention itself.²¹⁶ Where jurisdiction arises under Part XV, the United Kingdom emphasizes, it -

is confined to disputes concerning the interpretation or application of UNCLOS. It concerns UNCLOS and UNCLOS alone. It does not, unless expressly extended, concern other treaties, even other treaties on the law of the sea. Nor does it cover customary international law, even the customary international law of the sea such as is applicable between parties and non-parties or between non-parties.²¹⁷

With respect to the characterization of the Parties’ dispute, the United Kingdom recalls that the issue of sovereignty over the Chagos Archipelago is a longstanding point of contention. The formulation of the dispute as a matter arising under the Convention, however, is of recent origin and, according to the United Kingdom, arose only with the commencement of these proceedings.²¹⁸ It is telling, the United Kingdom argues, that the relief sought by Mauritius "has been formulated not in terms of a declaration of breach of UNCLOS, which is what one would expect to see if this were truly an UNCLOS claim."²¹⁹ Despite presenting its claim as one over the interpretation of the term "coastal State", the United Kingdom observes, Mauritius’ written pleadings do not contain "a single sentence on the correct interpretation of the term".²²⁰ Indeed, "the principal declaration sought by Mauritius is that the UK is not the coastal State."²²¹ Along the way to granting such relief, the United Kingdom notes, Mauritius invites the Tribunal to apply the law of self-determination to events in 1965 and to declare that Mauritius has retained sovereignty over the Chagos Archipelago. In the United Kingdom’s view, Mauritius is requesting the Tribunal to permit "an artificial re-characterization of the long-standing sovereignty dispute as a 'who is the coastal State' dispute."²²²

While other courts and tribunals exercising jurisdiction under the Convention have addressed some issues beyond the strict confines of the Convention itself, in the United Kingdom’s view none have done so to the extent now suggested by Mauritius. The United Kingdom distinguishes both Guyana v. Suriname (Award of 17 September 2007, PCA Award Series, p. 1, RIAA, Vol. XXX, p. 1) and MV Saiga (No. 2) ((Saint Vincent and the Grenadines v. Guinea), Judgment, ITLOS Reports 1999, p. 10) on the grounds that in each case "some incidental issue arose in relation to what was plainly a dispute as to the interpretation or application of UNCLOS."²²³ Here, in contrast, sovereignty is the principal issue and if the Tribunal were to decide that issue in Mauritius’ favour, "[t]here would be no UNCLOS case left... to decide".²²⁴ In short, the United Kingdom concludes, "the characterization of this long-established sovereignty claim as an UNCLOS claim, or as ancillary or incidental to a claim that could correctly be brought under UNCLOS, is untenable."²²⁵

According to the United Kingdom, this result is unaffected by the debate surrounding jurisdiction over mixed disputes involving the determination of maritime boundaries in areas where sovereignty over land features is also disputed. The present case does not arise in the context of a maritime boundary delimitation, the United Kingdom notes, and the arguments advanced in favour of jurisdiction over mixed disputes (discussed in greater detail in the context of Article 298(1)(a)(i) below) are specific to that context and can be left for other tribunals. The United Kingdom summarizes its objection as follows:

We do not, of course, contend for the existence of any implicit exclusion of all land sovereignty matters from article 288(1), [...]. We say that Mauritius’ 'we are the coastal State' claim is predicated on the determination of a long-standing dispute over a sovereignty that it wishes to be decided by reference to sources exterior to the Convention and, as such, on the ordinary meaning of article 288(1), the dispute is not one concerning the interpretation or application of the Convention.²²⁶

Mauritius submits that "all aspects of this dispute... are firmly within the jurisdiction of the Tribunal."²²⁷

Mauritius is not, it emphasizes, attempting to force a sovereignty dispute into the confines of the Convention. Instead, it is "inviting the Tribunal to determine whether or not the UK is a 'coastal State' within the meaning of the Convention, so that it is entitled to create the 'MPA' it has purported to establish."²²⁸ According to Mauritius, it "is not asking the Tribunal to widen or to extend its jurisdiction by looking at matters other than those 'concerning the interpretation and application of the Convention' under Article 288(1)."²²⁹ As Mauritius understands the issue:

Whether a state qualifies as "the coastal state" under the Convention (or "a coastal state," and we note the Convention uses both formulations) in respect of a particular state of affairs is a question arising under the Convention, and it can only be resolved by reference to the Convention itself and by general international law applicable in accordance with the Convention.²³⁰

In Mauritius’ view, "[t]he starting point is not the a priori question of whether Mauritius does or does not have sovereignty.... The correct starting point is whether or not this part of Mauritius’ claim concerns the interpretation or application of the Convention."²³¹ Mauritius considers that it obviously does. Having then raised a question relating to the interpretation and application of the Convention, Mauritius submits that the relevant question is "what other questions of public international law may be sufficiently closely connected to that dispute that they are questions the Tribunal can and must consider."²³² Where such issues do arise, Article 293 then permits the Tribunal to apply the other sources of international law necessary to resolve them.²³³

According to Mauritius, "[c]ompulsory procedures entailing binding decisions are available in every dispute concerning the interpretation or application of the Convention, unless an exception applies."²³⁴ Since neither the automatic exceptions to jurisdiction in Article 297 of the Convention, nor the optional ones in Article 298, are applicable, Mauritius submits that the United Kingdom is asking the Tribunal to find "that any dispute which may be construed as necessarily involving a question of sovereignty is inherently beyond the jurisdiction of a Part XV Tribunal despite the fact that there is nothing in the Convention that says that."²³⁵

Reviewing the drafting history of the Convention and the implications of Article 298(1)(a) (discussed in detail below), Mauritius submits that there is no basis for such an exception -

the idea of sovereignty was within the contemplation of the negotiators; they thought about it, they talked about it. Despite this, no consensus was reached on an explicit exclusion. If they truly did not wish a Tribunal such as this to deal with the words that are before you, such an express exclusion [...] could have been drafted and would have been included.²³⁶

Nor does Mauritius consider jurisdiction over land sovereignty issues to be relevant only in the context of maritime boundary delimitations.

Article 293 of the Convention provides as follows:

Article 293 Applicable law

1. A court or tribunal having jurisdiction under this section shall apply this Convention and other rules of international law not incompatible with this Convention.

2. Paragraph l does not prejudice the power of the court or tribunal having jurisdiction under this section to decide a case ex aequo et bono, if the parties so agree.

While the Parties are largely in agreement that Article 293 does not, of itself, constitute a basis of jurisdiction, they differ regarding the implications of this provision.

Mauritius submits that Article 293 of the Convention establishes that "issues 'closely linked or ancillary' to questions arising directly under the Convention are also questions 'concern[ing] the interpretation or application of the Convention.'"²³⁷ Mauritius "is not," it emphasizes, "asking this Tribunal to extend its jurisdiction by reference to rules of international law other than the Convention."²³⁸ Instead, Mauritius argues, "in compulsory jurisdiction cases, the Tribunal may have to decide matters of general international law that are not part of the law of the sea, and Article 293(1) allows for this."²³⁹ Mauritius summarizes the logical sequence as follows:

All the Convention asks us to consider first is whether there’s a dispute falling within the interpretation and application of the Convention (Article 288) and it then directs, if [the Tribunal is] satisfied that that is the case, [the Tribunal] "shall apply this Convention and other rules of international law not incompatible with this Convention" (Article 293).²⁴⁰

According to Mauritius, "ITLOS and Annex VII Tribunals have, on numerous occasions, indicated where other rules of international law are to be applied."²⁴¹ In this respect, Mauritius points to the application of the UN Charter provisions on the use of force in Guyana v. Suriname (Award of 17 September 2007, PCA Award Series, pp. 166-171, RIAA, Vol. XXX, p. 1 at p. 119, para. 425 et seq.) and of the determination of the permissibility of force as a matter of general international law in M/V "Saiga" (No. 2) ((Saint Vincent and the Grenadines v. Guinea), Judgment, ITLOS Reports 1999, p. 10 at p. 63, para. 159).²⁴² Mauritius also points to the considerations of human rights law at issue in Arctic Sunrise ((Kingdom of the Netherlands v. Russian Federation), Provisional Measures, Order of 22 November 2013, ITLOS Reports 2013, p. 230 at para. 33).²⁴³

According to the United Kingdom, Article 293 "cannot be invoked to support an expanded vision of the jurisdiction of a court or tribunal acting under section 2 of Part XV."²⁴⁴

In the United Kingdom’s view:

The purpose of the reference to "other rules of international law not incompatible with this Convention" is to dispel any doubt that, in interpreting and applying the provisions of the Convention, a Part XV court [or] tribunal may have recourse to such secondary rules as the law of treaties, State responsibility, diplomatic protection et cetera, and may apply other rules of international law when directed to do so expressly by a provision of the Convention.²⁴⁵

It is "most certainly not to empower a Part XV court or tribunal to decide disputes which have arisen in fields of international law that lie outside the provisions of the Convention."²⁴⁶

This distinction, the United Kingdom submits, was clearly established by the Order of 24 June 2003 in the MOX Plant Case ((Ireland v. United Kingdom), Order of 24 June 2003, PCA Award Series, p. 47 at p. 52, para. 19),²⁴⁷ and is supported by the approach of the ICJ in the Application of the Convention on the Prevention and Punishment of the Crime of Genocide ((Bosnia and Herzegovina v. Serbia and Montenegro), Judgment, I.C.J. Reports 2007, p. 43 at p. 104, para. 147) with respect to the comparable articles 36 and 38 of the ICJ Statute.²⁴⁸ It was also the approach of the Eurotunnel Tribunal with respect to the applicable law provisions of the contract at issue in those proceedings (Eurotunnel (Channel Tunnel Group and France-Manche v. UK and France), Partial Award of 30 January 2007, PCA Award Series p. 61, 132 ILR p. 1 at p.54, para. 152).²⁴⁹

The Parties disagree as to whether the effect of a declaration under Article 298(1)(a)(i) in excluding a dispute concerning sovereignty over land territory from compulsory conciliation implies a contrario that such a dispute would be subject to compulsory dispute resolution in the absence of such a declaration.

Article 298 of the Convention provides in relevant part:

1. When signing, ratifying or acceding to this Convention or at any time thereafter, a State may, without prejudice to the obligations arising under section 1, declare in writing that it does not accept any one or more of the procedures provided for in section 2 with respect to one or more of the following categories of disputes:

(a)(i) disputes concerning the interpretation or application of articles 15, 74 and 83 relating to sea boundary delimitations, or those involving historic bays or titles, provided that a State having made such a declaration shall, when such a dispute arises subsequent to the entry into force of this Convention and where no agreement within a reasonable period of time is reached in negotiations between the parties, at the request of any party to the dispute, accept submission of the matter to conciliation under Annex V, section 2; and provided further that any dispute that necessarily involves the concurrent consideration of any unsettled dispute concerning sovereignty or other rights over continental or insular land territory shall be excluded from such submission;

According to Mauritius, "there is no exclusion in the Convention of jurisdiction over mixed disputes either in the narrow sense of those arising in maritime delimitation cases or the broader sense of questions of public international law over which a Part XV Tribunal may properly exercise incidental or ancillary jurisdiction."²⁵⁰

Mauritius submits that the United Kingdom seeks to impose an artificial distinction and limit jurisdiction to the context of maritime boundaries. "The United Kingdom is wrong," Mauritius suggests, "to argue that the inference from the academic writings and from Article 298(1)(a)(i) itself is that sovereignty questions could only arise under Part XV where they are 'mixed' with a delimitation dispute..."²⁵¹ While "[d]elimitation is simply the most obvious case in which [a mixed dispute] could arise",²⁵² Mauritius considers that the reasoning supporting such jurisdiction applies equally to other issues that "cannot be determined in isolation without reference to territory."²⁵³ Nevertheless, Mauritius recalls the dispute between the Parties concerning Mauritius’ submissions to the CLCS in respect of the Chagos Archipelago and argues that "we do now have a situation of maritime boundaries in this case because the delineation issue, we say, is a maritime boundary issue."²⁵⁴ In Mauritius’ view, there is simply no reason for delimitation and delineation to be treated differently with respect to jurisdiction.²⁵⁵

According to Mauritius, this interpretation follows from the inclusion in the Convention of Article 298(1)(a)(i): "If, indeed, mixed disputes were not otherwise covered by the Convention’s jurisdiction, there would have been no need for the specific exclusion in the last clause of Article 298(1)(a)(i)."²⁵⁶ It also follows from the negotiating records of the Convention, insofar as, according to Mauritius, "an express exclusion [of jurisdiction over land sovereignty] was proposed and it was rejected" during the Third United Nations Conference on the Law of the Sea (the "Conference").²⁵⁷ The Report of the President of the Conference of 23 August 1980, Mauritius notes, records that a proposal was made to make "the exclusion of past or existing delimitation disputes as well as disputes relating to sovereignty over land or insular territories from the compulsory dispute settlement procedures and from compulsory submission to conciliation procedures"²⁵⁸ part of the automatic exclusions from jurisdiction (now set out in Article 297), but that this was rejected.²⁵⁹ Taken as a whole, Mauritius argues:

The travaux plainly point to one conclusion. The issue of sovereignty over land was addressed, and a majority wanted a compulsory dispute settlement system capable of touching on such questions. A minority did not. All the minority got was the opt-out in Article 298(1)(a)(i), and that became part of the package deal.²⁶⁰

Mauritius discounts the academic commentaries assembled by the United Kingdom to suggest that land sovereignty must be outside the Tribunal’s jurisdiction. According to Mauritius, of the authorities offered by the United Kingdom:

Many, [...] merely assert that Part XV cannot cover issues of territorial sovereignty: they offer no footnote and no explanation and no reasoning, beyond—at most—a bald reference to the words of Article 298(1)(a)(i), unaccompanied by any further textual analysis. [...] Another three attempt some explanation of their views but offer no reasoning at all beyond a sentence or two (that is Churchill, Oxman and Thomas). Closely read, at least two of the authors cited do not actually seem to rule out the possibility of jurisdiction in at least some sovereignty disputes (Torres Bernárdez and Smith). In fact quite a few of the authors cited use language along the lines of the Convention seeming, or appearing to, or probably, excluding such disputes, but they don't actually offer a firm conclusion. One author (Adede) makes the historical point that the President of the Conference in 1977 said, in his view, territorial disputes would not fall within Part XV and another, Yee, simply repeats that observation.²⁶¹

Mauritius summarises its position as follows:

The result of a proper a contrario understanding of Article 298(1)(a)(i) is not that all sovereignty disputes are automatically included under the Convention, it is that such disputes are not automatically excluded. Not every question relating to land will fall within the Convention, only those which must necessarily be dealt with in order to resolve a dispute that is within the Convention. The question is, as Professor Treves has put it, "whether the dispute, [...] as a whole, can be seen as being about the interpretation or application of the Convention."²⁶²

The United Kingdom acknowledges that there is an extensive debate in the academic literature as to whether issues of land sovereignty may be decided through compulsory dispute settlement under the Convention when they arise incidentally to a maritime boundary delimitation. As the present proceedings do not involve the delimitation of a maritime boundary, the United Kingdom is of the view that the Tribunal "need not and should not enter into the debate on mixed disputes to decide this case."²⁶³ To the extent the question is relevant, however, the United Kingdom endorses the view that land sovereignty disputes were excluded from jurisdiction under the Convention and cites numerous authorities in support of this view.²⁶⁴

In the United Kingdom’s view, "the proviso to Article 298(1)(a)(i) merely clarifies that the general exclusion of unsettled territorial sovereignty disputes from compulsory dispute settlement also applies in the context where such a dispute would fall for consideration... in the context of mandatory conciliation".²⁶⁵ But whatever one makes of the a contrario argument, the United Kingdom submits, it does not assist Mauritius in the present case. Article 298(1)(a)(i) "is concerned only with disputes over maritime delimitation and historic bays or titles."²⁶⁶ For the United Kingdom, it therefore follows that any a contrario reading of the provision is similarly limited to maritime boundary delimitation. Rather than infer, as Mauritius asks the Tribunal to do, that "because jurisdiction can be excluded pursuant to a declaration in context 'A', it must therefore be included in context 'B'," the United Kingdom submits that "[t]he more obvious conclusion is that [jurisdiction] was not included in context 'B' in the first place."²⁶⁷ Moreover, the United Kingdom argues, Mauritius’ interpretation is illogical:

It posits certain States being utterly unwilling to agree to determine territorial disputes where these arose in the context of maritime delimitation claims, and insisting on the terms of the Article 298 opt-out (which excludes sovereignty disputes even from conciliation), but at the same time those very same States being willing to agree to the compulsory determination of such disputes in the far broader context of claims made wherever the Convention refers to a coastal state.²⁶⁸

Were this the case, the United Kingdom submits, "there would be an opt-out for 'who is the coastal State' disputes".²⁶⁹

Turning to the negotiating record of Article 298(1)(a)(i), the United Kingdom emphasizes that all of the statements identified by Mauritius as allegedly supporting jurisdiction over land sovereignty disputes were made in the context of Negotiating Group 7 and "in each case, the delegate relied on had been making a statement on land sovereignty issues in the specific context of maritime delimitation disputes."²⁷⁰ Simply put, the United Kingdom argues -

The debates do not reflect any consideration of any kind of the possibility that a justiciable dispute as to land sovereignty could be raised in the context of [...] who was the, or indeed a, coastal State. The supposed majority does not exist, because no one was considering what Mauritius is now proposing.²⁷¹

Instead, "the negotiating history does no more than confirm that there is no foundation whatsoever for the radical and unwarranted jurisdiction that Mauritius contends for in this case."²⁷²

The United Kingdom advances a cautionary argument against finding jurisdiction over Mauritius’ First Submission. In the United Kingdom’s view, the risks involved in disregarding limits to jurisdiction were recalled by Judge Koroma in the context of comparable provisions in Georgia v. Russia -

a link must exist between the substantive provisions of the treaty invoked and the dispute. This limitation is vital. Without it, States could use the compromissory clause as a vehicle for forcing an unrelated dispute with another State before the Court.

(Application of the International Convention on the Elimination of all Forms of Racial Discrimination (Georgia v. Russian Federation), Preliminary Objections, Judgment, Separate Opinion of Judge Koroma, I.C.J. Reports 2011, p. 183 at p. 185, para. 7.)

Here, the United Kingdom submits that the open-ended approach to jurisdiction advocated by Mauritius risks opening the door to a wide range of latent sovereignty disputes among States worldwide, brought on the pretext that one State or another is not the "coastal State" with respect to the territory in question. For the United Kingdom, there is a "grave danger in abuse of Part XV represented by Mauritius’ arguments in the present case," and "[t]he arguments of Mauritius’ lawyers risk undermining the system of Part XV" as States would be dissuaded from acceding to the Convention or accepting the jurisdiction of other courts and tribunals.²⁷³

While Mauritius contends that its case is sui generis and limited by the colonial history of the Chagos Archipelago, the United Kingdom submits that -

[t]here is no wording in Articles 288(1) or 298(1) to suggest that they somehow apply differently in different circumstances. No references to the impacts of undertakings or jurisdiction with respect to former colonies. So if Mauritius is correct in its interpretation of Article 288(1), then, as long as the claimant State can plausibly assert that the respondent State is exercising the rights or duties of a coastal State, that claimant State will be able to bring a claim challenging the territorial sovereignty of the respondent State.²⁷⁴

Mauritius rejects the United Kingdom’s concerns about the consequences of finding jurisdiction in this case. Mauritius describes an evolutionary process in the application of compulsory dispute settlement under the Convention -

with the passage of time, as dispute settlement under the 1982 Convention and Part XV has become increasingly established and settled, as the International Tribunal for the Law of the Sea and Annex VII Tribunals have been confronted with a range of issues and questions that may not have been at the forefront of the minds of the drafters of the Convention, or indeed in their minds at all, sensible solutions have been found, and the law has evolved. Those solutions have been practical and they have been effective. It is true that they may have taken the interpretation of the Convention to a place where some of the early writings that the United Kingdom likes to rely upon may not have foreseen and may not like. But it cannot be said that disaster has followed.²⁷⁵

The result of that process, according to Mauritius, is not a threat to the system, but the effective application of the Convention to resolve disputes -

the reality is the very opposite of what the United Kingdom argues: far from undermining the whole Convention, if [the Tribunal] take[s] jurisdiction over this case, [it] will strengthen the dispute settlement structure of the Convention; to decline jurisdiction will be to exacerbate the dispute, to prolong it unnecessarily, and to signal that Part XV serves to perpetuate a colonial era dispute such as this one.²⁷⁶

In any event, however, Mauritius contends that the circumstances of the Chagos Archipelago are unique:

The United Kingdom has consistently described Mauritius as having rights in reversion of the islands. It has described itself as a mere "temporary freeholder." This fact alone places this dispute in a category of one. No other case like it anywhere, and the United Kingdom has not been able to find one for us.²⁷⁷

According to Mauritius, this "is the key to this case. It allows you to open the door that leads to the particular facts of this unique dispute."²⁷⁸ However, "to admit one dispute touching upon such matters is not to admit them all," and "not all such disputes will necessarily come within the jurisdiction of a Part XV court or tribunal."²⁷⁹ In Mauritius’ view, the Tribunal should concern itself "with the facts of this case and this dispute and this case and this dispute only and no other."²⁸⁰

Mauritius’ First Submission asks the Tribunal to interpret and apply the term "coastal State" as it is used in the Convention. This term is not defined in the Convention, although its usage in the text makes evident that it was intended to denote a State having a sea coast, as distinct from a land-locked State. Nowhere, however, does the Convention provide guidance on the identification of the "coastal State" in cases where sovereignty over the land territory fronting a coast is disputed. Nor is provision made for circumstances of war or secession in which a coast might effectively be occupied by authorities exercising de facto governmental powers, or other complex permutations of territorial sovereignty, such as condominium governments. In each of these cases, the identity of the coastal State for the purposes of the Convention would be a matter to be determined through the application of rules of international law lying outside the international law of the sea. Whether the Tribunal, or other courts and tribunals convened pursuant to Part XV of the Convention, may apply such exterior sources of law and address such matters raises a question of the scope of jurisdiction under the Convention. On this point, the United Kingdom objects to Mauritius’ First Submission.

The Tribunal’s subject matter jurisdiction is set out in Article 288(1) of the Convention, which provides as follows:

1. A court or tribunal referred to in article 287 shall have jurisdiction over any dispute concerning the interpretation or application of this Convention which is submitted to it in accordance with this Part.

Although expressed in general terms, Article 288(1) is then limited by the provisions of section 3 of Part XV, which restrict the compulsory settlement of disputes with respect to certain subject matters. Within section 3, Article 297 sets out a series of limitations and exceptions to compulsory settlement that apply automatically and which will be discussed in the Tribunal’s consideration of Mauritius’ Fourth Submission (see paragraphs 283-323 below). Article 298 permits States, by declaration, to exclude certain additional matters from compulsory settlement.

Neither Party has suggested that any of the automatic exceptions set out in Article 297 bears upon the Tribunal’s jurisdiction with respect to Mauritius’ First Submission. Nor has either Party made any relevant declaration pursuant to Article 298. The question of the Tribunal’s jurisdiction therefore hinges entirely on whether the issues raised in Mauritius’ First Submission represent a dispute "concerning the interpretation or application" of the Convention. In the Tribunal’s view, this question consists of two parts: first, what is the nature of the dispute encompassed in Mauritius’ First Submission? Second, to the extent that the Tribunal finds the Parties’ dispute to be, at its core, a matter of territorial sovereignty, to what extent does Article 288(1) permit a tribunal to determine issues of disputed land sovereignty as a necessary precondition to a determination of rights and duties in the adjacent sea?

As set out above (see paragraph 172), the United Kingdom considers Mauritius’ First Submission to be "an artificial re-characterisation of the long-standing sovereignty dispute as a 'who is the coastal State' dispute."²⁸¹ Mauritius, in turn, (see paragraphs 176-177 above) considers that it is merely asking the Tribunal to interpret the term "coastal State" as it is used repeatedly in the text of the Convention itself.

Ultimately, it is for the Tribunal itself "while giving particular attention to the formulation of the dispute chosen by the Applicant, to determine on an objective basis the dispute dividing the parties, by examining the position of both parties" (Fisheries Jurisdiction (Spain v. Canada), Jurisdiction of the Court, Judgment, I.C.J. Reports 1998, p. 432 at p. 448, para. 30) and in the process "to isolate the real issue in the case and to identify the object of the claim" (Nuclear Tests (New Zealand v. France), Judgment, I.C.J. Reports 1974, p. 457 at p. 466, para. 30).

In the Tribunal’s view, the record (see paragraphs 101-107 above) clearly indicates that a dispute between the Parties exists with respect to sovereignty over the Chagos Archipelago. Since at least 1980, Mauritius has asserted its sovereignty over the Chagos Archipelago in a variety of fora, including in bilateral communications with the United Kingdom and in statements to the United Nations. Mauritius has also challenged the circumstances by which the Archipelago was detached; questioned the validity of the Mauritius Council of Ministers’ approval of that decision; enshrined a claim to sovereignty over the Archipelago in its Constitution and legislation; and declared its own exclusive economic zone in the surrounding waters. Finally, the pleadings in these proceedings are replete with assertions of Mauritian sovereignty over the Chagos Archipelago.

In the Tribunal’s view, however, a dispute also exists between the Parties with respect to the manner in which the MPA was declared and the implications of the MPA for the Lancaster House Undertakings, made by the United Kingdom in connection with the detachment of the Archipelago. This dispute is distinct from the matter of sovereignty and will be the subject of further consideration in connection with Mauritius’ Fourth Submission.

Finally, the Parties clearly differ regarding the identity of the "coastal State". For the purpose of characterizing the Parties’ dispute, however, the Tribunal must evaluate where the relative weight of the dispute lies. Is the Parties’ dispute primarily a matter of the interpretation and application of the term "coastal State", with the issue of sovereignty forming one aspect of a larger question? Or does the Parties’ dispute primarily concern sovereignty, with the United Kingdom’s actions as a "coastal State" merely representing a manifestation of that dispute? In the Tribunal’s view, this question all but answers itself. There is an extensive record, extending across a range of fora and instruments, documenting the Parties’ dispute over sovereignty. In contrast, prior to the initiation of these proceedings, there is scant evidence that Mauritius was specifically concerned with the United Kingdom’s implementation of the Convention on behalf of the BIOT. Moreover, as Mauritius itself has argued its case, the consequences of a finding that the United Kingdom is not the coastal State extend well beyond the question of the validity of the MPA. In the words of Mauritius’ counsel, the Tribunal is "entitled" to -

rule that the United Kingdom is [...] not "the coastal State" of the Chagos Archipelago. The skies will not fall if [the Tribunal] so rule[s], although this "Marine Protected Area" will. The Tribunal will do no more than state that Mauritius is the "coastal State" in relation to the Chagos Archipelago and that the Chagos Archipelago forms an integral part of the Republic of Mauritius. The American base will not be affected, as we have shown. The British will leave. The former residents of the Chagos Archipelago who wish to return finally will be free to do so and their exile will come to an end. Contrary to the United Kingdom’s submissions, [...] those are the consequences that flow from applying the law, from exercising jurisdiction and interpreting and applying the words that sit in the Convention.²⁸²

These are not the sort of consequences that follow from a narrow dispute regarding the interpretation of the words "coastal State" for the purposes of certain articles of the Convention.

Accordingly, the Tribunal concludes that the Parties’ dispute with respect to Mauritius’ First Submission is properly characterized as relating to land sovereignty over the Chagos Archipelago. The Parties’ differing views on the "coastal State" for the purposes of the Convention are simply one aspect of this larger dispute.

The Tribunal’s conclusion that the Parties’ dispute in respect of Mauritius’ First Submission is, at its core, a dispute over sovereignty does not definitively answer the question of jurisdiction. There remains the question of the extent to which Article 288(1) accords the Tribunal jurisdiction in respect of a dispute over land sovereignty when, as here, that dispute touches in some ancillary manner on matters regulated by the Convention.

In the course of these proceedings, the Parties devoted a great deal of argument to whether jurisdiction over issues of land sovereignty was, or was not, contemplated by the drafters of the Convention. The Parties also debated whether an a contrario reading of Article 298(1)(a)(i) supports the view that land sovereignty is generally within the jurisdiction of a Part XV court or tribunal. Article 298(1)(a)(i) permits States to exclude disputes regarding maritime boundaries and historic bays or titles from compulsory settlement, requires submission instead to compulsory conciliation, and provides that "any dispute that necessarily involves the concurrent consideration of any unsettled dispute concerning sovereignty or other rights over continental or insular land territory shall be excluded from such submission [to conciliation]."

In the Tribunal’s view, much of this argumentation misses the point. The negotiating records of the Convention provide no explicit answer regarding jurisdiction over territorial sovereignty. The Tribunal considers that the simple explanation for the lack of attention to this question is that none of the Conference participants expected that a long-standing dispute over territorial sovereignty would ever be considered to be a dispute "concerning the interpretation or application of the Convention."

The negotiation of the Convention involved extensive debate regarding the extent to which disputes concerning its provisions would be subject to compulsory settlement. The distrust with which some participants at the Conference viewed compulsory settlement is evidenced by the inclusion in the final texts of substantial carve outs, in Article 297, for disputes relating to the exercise of sovereign rights and jurisdiction in the exclusive economic zone. It is also apparent in the option, in Article 298(a)(i), for States to exclude the delimitation of maritime boundaries from dispute settlement, subject only to the requirement of compulsory conciliation. Given the inherent sensitivity of States to questions of territorial sovereignty, the question must be asked: if the drafters of the Convention were sufficiently concerned with the sensitivities involved in delimiting maritime boundaries that they included the option to exclude such disputes from compulsory settlement, is it reasonable to expect that the same States accepted that more fundamental issues of territorial sovereignty could be raised as separate claims under Article 288(1)?

In the Tribunal’s view, had the drafters intended that such claims could be presented as disputes "concerning the interpretation or application of the Convention", the Convention would have included an opt-out facility for States not wishing their sovereignty claims to be adjudicated, just as one sees in Article 298(1)(a)(i) in relation to maritime delimitation disputes.

Mauritius suggests that the opposite conclusion can be reached by reading Article 298(1)(a)(i) a contrario : if it was necessary for that Article to expressly state that disputes concerning sovereignty over continental or insular land territory are excluded from compulsory conciliation when a declaration pursuant to the Article is made, then a fortiori it must be the case that such disputes fall within the ambit of compulsory settlement when no such declaration is made. The Tribunal is not convinced by this argument. Article 298(1)(a)(i) relates only to the application of the Convention to disputes involving maritime boundaries and historic titles. At most, an a contrario reading of the provision supports the proposition that an issue of land sovereignty might be within the jurisdiction of a Part XV court or tribunal if it were genuinely ancillary to a dispute over a maritime boundary or a claim of historic title.

This case, however, is not such a dispute. In the Tribunal’s view, to read Article 298(1)(a)(i) as a warrant to assume jurisdiction over matters of land sovereignty on the pretext that the Convention makes use of the term "coastal State" would do violence to the intent of the drafters of the Convention to craft a balanced text and to respect the manifest sensitivity of States to the compulsory settlement of disputes relating to sovereign rights and maritime territory. Such sensitivities arise to an even greater degree in relation to land territory.

As a general matter, the Tribunal concludes that, where a dispute concerns the interpretation or application of the Convention, the jurisdiction of a court or tribunal pursuant to Article 288(1) extends to making such findings of fact or ancillary determinations of law as are necessary to resolve the dispute presented to it (see Certain German Interests in Polish Upper Silesia, Preliminary Objections, Judgment of 25 August 1925, P.C.I.J. Series A, No. 6, p. 4 at p. 18). Where the "real issue in the case" and the "object of the claim" (Nuclear Tests (New Zealand v. France), Judgment, I.C.J. Reports 1974, p. 457 at p. 466, para. 30) do not relate to the interpretation or application of the Convention, however, an incidental connection between the dispute and some matter regulated by the Convention is insufficient to bring the dispute, as a whole, within the ambit of Article 288(1).

The Tribunal does not categorically exclude that in some instances a minor issue of territorial sovereignty could indeed be ancillary to a dispute concerning the interpretation or application of the Convention. That, however, is not this case, and the Tribunal therefore has no need to rule upon the issue. The Parties’ dispute regarding sovereignty over the Chagos Archipelago does not concern the interpretation or application of the Convention. Accordingly, the Tribunal finds itself without jurisdiction to address Mauritius’ First Submission.

In its Second Submission, Mauritius requests the Tribunal to adjudge and declare that -

[...]

(2) having regard to the commitments that it has made to Mauritius in relation to the Chagos Archipelago, the United Kingdom is not entitled unilaterally to declare an "MPA" or other maritime zones because Mauritius has rights as a "coastal State" within the meaning of inter alia Articles 56(1)(b)(iii) and 76(8) of the Convention; and/or

[...]

The United Kingdom objects to the Tribunal’s jurisdiction to address Mauritius’ claim that it has rights as "a" coastal State for the same reasons for which it objects to Mauritius’ First Submission that the United Kingdom is not the coastal State.

According to the United Kingdom, Mauritius "again is asking the Tribunal to engage in issues of sovereignty, although it is some sort of reversionary rather than actual sovereignty, and it follows from that that the jurisdictional issues are the same."²⁸³ "The only basis", in the United Kingdom’s view, "for saying that Mauritius is 'a' coastal State is understood to be that it has what are said to be certain attributes of a coastal State, i.e., some reversionary interest in sovereignty."²⁸⁴ Accordingly, "the only difference... is that [the Tribunal is] not being asked to interpret and apply the laws on self-determination, but instead other sources of alleged international law exterior to the Convention, which sources are said to establish the form of reversionary sovereignty".²⁸⁵ In the United Kingdom’s view, this amounts to a legal construct: "Mauritius wishes [the Tribunal] to interpret and apply the 1965 understandings, in one way or another, and it looks for some hook in the 1982 Convention."²⁸⁶

In any event, the United Kingdom notes, "there is no suggestion anywhere in UNCLOS that there could be more than one coastal State in the way that Mauritius contends for."²⁸⁷

Mauritius distinguishes the question of the Tribunal’s jurisdiction to find that Mauritius "has the attributes of a coastal State" from the question of jurisdiction to declare that the United Kingdom is not the coastal State.

According to Mauritius, in addressing Mauritius’ Second Submission, the Tribunal does -

not have to consider whether Part XV excludes all, or any, disputes related to land sovereignty. These aspects of our claim do not require [the Tribunal] to consider which State is currently exercising sovereignty over the Chagos Archipelago. We are proceeding here on the basis that the Archipelago will be returned to the sovereignty of Mauritius when it is no longer needed for defence purposes and because of the exclusive rights in regard to the living and non-living resources with which Mauritius has already been vested. Our claims of entitlement to be regarded as a coastal State for purposes of Articles 56(1)(b)(iii) and 76(8), because of the attributes of a coastal State which Mauritius acquired as a result of the UK’s undertakings, are indisputably matters calling for [the Tribunal's] interpretation and application of those two provisions of the Convention, and the meaning of the words "coastal State" under them and, as such, they plainly fall within [the Tribunal's] jurisdiction under Article 288(1).²⁸⁸

Mauritius considers that "[t]here can be no reason... why the dispute about how the Convention can be applied in the light of [Mauritius'] rights and [the United Kingdom's] undertakings should be excluded from [the Tribunal's] jurisdiction."²⁸⁹

The Parties disagree both as to whether Mauritius’ Second Submission presents a distinct issue from the First Submission, which the Tribunal has already considered, and as to whether the Tribunal’s jurisdiction extends to Mauritius’ Second Submission. In the United Kingdom’s view, the issues raised by the two submissions are the same, except that in its Second Submission, Mauritius claims only a form of reversionary sovereignty. According to Mauritius, its Second Submission is distinct and does not require a determination of sovereignty. Instead, Mauritius claims that the Lancaster House Undertakings endowed Mauritius with the attributes of a coastal State for the purposes of the Convention.

The Tribunal agrees with Mauritius that the issues presented by its First and Second Submissions are distinct, but is nevertheless of the view that Mauritius’ Second Submission must be viewed against the backdrop of the Parties’ dispute regarding sovereignty over the Chagos Archipelago. Although in its Second Submission Mauritius asks only for the Tribunal to determine that it has rights as "a coastal State", the Tribunal considers that such a determination would effectively constitute a finding that the United Kingdom is less than fully sovereign over the Chagos Archipelago. As with Mauritius’ First Submission, the Tribunal evaluates where the weight of the Parties’ dispute lies. In carrying out this task, the Tribunal does not consider that its role is limited to parsing the precise wording chosen by Mauritius in formulating its submission. On the contrary, the Tribunal is entitled, and indeed obliged, to consider the context of the submission and the manner in which it has been presented in order to establish the dispute actually separating the Parties. Again, the Tribunal finds that the Parties’ underlying dispute regarding sovereignty over the Archipelago is predominant. The question of the "coastal State"—now presented in terms of the "attributes of a coastal State"—remains merely an aspect of this larger dispute.

The Tribunal accepts that a dispute exists between the Parties concerning the manner in which the MPA was declared. Nevertheless, the Tribunal is of the view that the true "object of the claim" (Nuclear Tests (New Zealand v. France), Judgment, I.C.J. Reports 1974, p. 457 at p. 466, para. 30) in Mauritius’ Second Submission is to bolster Mauritius’ claim to sovereignty over the Chagos Archipelago. The Tribunal also notes that the relief sought by Mauritius in its First and Second Submissions is the same: a declaration that the United Kingdom was not entitled to declare the MPA. Accordingly, and notwithstanding the difference in presentation, the Tribunal concludes that Mauritius’ Second Submission is properly characterized as relating to the same dispute in respect of land sovereignty over the Chagos Archipelago as Mauritius’ First Submission. The Tribunal therefore finds itself without jurisdiction to address Mauritius’ Second Submission.

The United Kingdom objects to the Tribunal’s jurisdiction over Mauritius’ Fourth Submission and its claims concerning the compatibility of the MPA with the Convention (what the United Kingdom describes as the "non-sovereignty claims"). Mauritius maintains its position that the Tribunal has jurisdiction over these claims.

Both Parties approach this question with reference to the mandatory exceptions to compulsory jurisdiction set out in Article 297 of the Convention. Broadly speaking, Mauritius contends that the MPA is an environmental measure and that the jurisdiction of this Tribunal is therefore established by Article 297(1)(c) concerning the protection of the environment. The United Kingdom, in contrast, considers the MPA to be a measure relating to "sovereign rights with respect to living resources" in the exclusive economic zone and argues that jurisdiction is precluded by Article 297(3)(a) concerning fisheries. The United Kingdom also objects, separately, to jurisdiction over Mauritius’ claims regarding straddling and highly migratory fish stocks, fisheries access in both the territorial sea and exclusive economic zone, the harvesting of the sedentary species of the continental shelf, marine pollution, and the abuse of rights. The Parties’ positions on each of these issues will be set out in turn in the sections that follow.

Article 297(1) of the Convention provides as follows:

Article 297

Limitations on applicability of section 2

1. Disputes concerning the interpretation or application of this Convention with regard to the exercise by a coastal State of its sovereign rights or jurisdiction provided for in this Convention shall be subject to the procedures provided for in section 2 in the following cases:

(a) when it is alleged that a coastal State has acted in contravention of the provisions of this Convention in regard to the freedoms and rights of navigation, overflight or the laying of submarine cables and pipelines, or in regard to other internationally lawful uses of the sea specified in article 58;

(b) when it is alleged that a State in exercising the aforementioned freedoms, rights or uses has acted in contravention of this Convention or of laws or regulations adopted by the coastal State in conformity with this Convention and other rules of international law not incompatible with this Convention; or

(c) when it is alleged that a coastal State has acted in contravention of specified international rules and standards for the protection and preservation of the marine environment which are applicable to the coastal State and which have been established by this Convention or through a competent international organization or diplomatic conference in accordance with this Convention.

The United Kingdom submits that "Article 297(1)(c) provides no basis for jurisdiction over the declaration of an MPA or the ban on commercial fishing."²⁹⁰ According to the United Kingdom -

the purpose of this provision, like paragraph (1) as a whole, is to protect freedom of navigation, or the other freedoms referred to in Article 58, against misuse by the coastal States of their power to regulate marine pollution. It does not cover environmental disputes in general, and specifically it does not cover this dispute.²⁹¹

The United Kingdom looks to the structure of Article 297(1), and notes that it is generally concerned with navigation, overflight, cables, and pipelines. Fishing and the management of living resources are distinct, the United Kingdom argues, and "obviously fall[] outside the context of Article 297(1) read as a whole."²⁹² Thus, the United Kingdom concludes "even if we do characterise the MPA and the ban on commercial fishing as having an environmental purpose, this will not be sufficient to bring the present case within Article 297(1)(c)."²⁹³

The United Kingdom emphasizes the requirement in Article 297(1)(c) that a dispute concern "specified international rules and standards for the protection and preservation of the marine environment which are applicable to the coastal State."²⁹⁴ Where the phrase "international rules and standards" appears in the Convention, the United Kingdom notes, it is consistently to "empower or require coastal States, flag States, or port States to regulate and enforce regulations for the prevention of marine pollution from ships, aircraft, and seabed activities,"²⁹⁵ and "none of these articles covers anything resembling a marine protected area whose purpose is to manage and conserve living resources in the EEZ".²⁹⁶

With respect to fisheries, the United Kingdom argues, the Convention’s approach is different: "far from endorsing any commitment to international regulation, in Part V it is the laws of the coastal State that prevail."²⁹⁷ The United Kingdom continues:

There are no internationally agreed rules and standards on those subjects, none on the conservation and management of marine living resources which could fit within the terminology used in Article 297(1)(c) and the other articles of the Convention to which Mauritius refers do not do so. There is no fisheries equivalent of MARPOL or SOLAS or the London Dumping Convention.²⁹⁸

Turning to the various articles of the Convention itself invoked by Mauritius, the United Kingdom submits that "the very general wording of articles 55, 56, 63, 64, and 194 also contradicts any suggestion that they could constitute 'specified international rules and standards.'"²⁹⁹ In the United Kingdom’s view:

(a) Article 55 "simply defines the exclusive economic zone";³⁰⁰

(b) Article 56 "provides the legal basis for the United Kingdom’s right as a coastal State to regulate the exclusive economic zone of BIOT and, in particular to regulate conservation and management of living resources, but it specifies no particular international rules and standards for doing so";³⁰¹

(c) Articles 63 and 64 require international cooperation, but neither "identifies specific international rules and standards: at best they encourage States to negotiate such rules and standards";³⁰² and

(d) "Article 194 sets out the obligation of States parties to take measures necessary to prevent reduce and control pollution,"³⁰³ but "does not itself constitute or incorporate specified international rules and standards; indeed it makes no reference to them".³⁰⁴

In sum, the United Kingdom concludes -

the point of Article 297(1)(c)—and this is entirely consistent with articles 297(1)(a) and (b)—is to protect freedom of navigation, or the other freedoms referred to in Article 58, against misuse by coastal States of their power to regulate marine pollution. And that interpretation is consistent with the two previous sub-paragraphs and it reflects their focus on navigation and pipelines and it reflects the wording of the article itself. But bringing articles 55, 56, 63, 64 and 194 into the ambit of Article 297(1)(c) achieves neither coherence nor contextual consistency with the rest of Article 297(1).³⁰⁵

Mauritius contends that the Tribunal has jurisdiction to address the compatibility of the MPA with the Convention because Mauritius’ claims "concern the contravention of specified international rules or standards for the protection and preservation of the marine environment, matters over which [the Tribunal has] jurisdiction under Article 297(1)."³⁰⁶

Mauritius rejects the objection that Article 297(1) is limited to the context of navigational rights, overflight, cables and pipelines. Mauritius notes that that "limitation appears only in (1)(a) and (1)(b). It does not appear in (1)(c)."³⁰⁷ For Mauritius, this is significant, and reflects the intention for Article 297(1)(c) to be of broader application than the preceding provisions. For similar reasons, Mauritius also rejects the United Kingdom’s attempt to limit Article 297(1)(c) to the context of marine pollution. In Mauritius’ view, "marine pollution may fall within the general category of environmental protection and preservation, but there is no textual basis on which to conclude that 297(1)(c) is confined solely and exclusively to marine pollution."³⁰⁸

With respect to whether the identified provisions of the Convention are rules or standards within the meaning of Article 297(1)(c), Mauritius submits simply that "each of the articles alleged to have been contravened by the UK—Article 194 stands out in particular—establish a binding obligation and each relates to the protection or preservation of the marine environment. Nothing more is required."³⁰⁹

Finally, Mauritius submits that the Tribunal need not be concerned that the MPA deals with both the marine environment and fisheries. According to Mauritius, the interplay between Article 297(1)(c) and Article 297(3) operates as follows:

297(1)(c) and 297(3) are both affirmative grants of jurisdiction, though in the case of 297(3) the grant is limited by an exception. The fact that 297(1)(c) and 297(3) are independent grants of jurisdiction means that an Applicant need only satisfy one of them. It also means that a dispute that falls within a Tribunal’s jurisdiction because it concerns an alleged contravention of an international rule or standard for the protection or preservation of the marine environment, cannot be excluded from jurisdiction if it may also be said to involve a coastal State’s sovereign rights over the living resources of the EEZ or their exercise. If a dispute falls within 297(1)(c), jurisdiction is established. The exception contained in 297(3) is irrelevant.³¹⁰

Article 297(3)(a) provides as follows:

Article 297

Limitations on applicability of section 2

[...]

3. (a) Disputes concerning the interpretation or application of the provisions of this Convention with regard to fisheries shall be settled in accordance with section 2, except that the coastal State shall not be obliged to accept the submission to such settlement of any dispute relating to its sovereign rights with respect to the living resources in the exclusive economic zone or their exercise, including its discretionary powers for determining the allowable catch, its harvesting capacity, the allocation of surpluses to other States and the terms and conditions established in its conservation and management laws and regulations.

The United Kingdom submits that the MPA is properly characterized as a fisheries measure, noting that "whatever their purpose, the only implementation measures actually adopted so far are the ban on commercial fishing and the new regulations on illegal fishing."³¹¹ As such, it is properly subject to the limitation on jurisdiction expressed in Article 297(3)(a). According to the United Kingdom -

a dispute relating to conservation and management of fish stocks and other living resources in the exclusive economic zone is excluded from compulsory jurisdiction by Article 297(3)(a) unless the coastal State agrees. This provision [...] is fatal for Mauritius’ challenge to the ban on commercial fishing within the BIOT MPA. And it is fatal even if the MPA’s purpose is characterised as environmental, since the wording of Article 297(3)(a) takes no account of the purpose for which the discretionary powers of the coastal State have been exercised.³¹²

"Article 297(3)(a)", the United Kingdom argues, "is unambiguous and there is no basis for looking beyond its clear terms."³¹³ In the United Kingdom’s view, Article 297(3)(a) grants jurisdiction over fisheries disputes generally and then excludes jurisdiction over fisheries disputes in the exclusive economic zone. As a result, "high seas fisheries disputes are within compulsory jurisdiction, EEZ living resources, quite deliberately, are not."³¹⁴ According to the United Kingdom, this result is "entirely consistent with the UNCLOS negotiating record."³¹⁵ Recalling that record, the United Kingdom submits that "the object of this whole provision, particularly 297(3), is to keep coastal State fisheries disputes out of court as far as possible. That’s what coastal States wanted, particularly Developing States, when they asked for creation of the exclusive economic zone."³¹⁶ As such, the United Kingdom submits, "[i]n advocating an evolutionary and environmental interpretation of Article 297 Mauritius invites you to overturn a clear policy preference of the negotiating States at [the Conference]."³¹⁷

For the United Kingdom, Mauritius’ attempt to parse the language of Article 297(3)(a) and to distinguish between fishing in the exclusive economic zone and the exercise of sovereign rights in the exclusive economic zone (and to argue that the former is permitted) fails. According to the United Kingdom, "Article 297(3) makes no jurisdictional distinction between an exercise of sovereign rights that affects other states and one that does not affect other states",³¹⁸ and "[i]t seems self-evident that the grant or denial of a licence to fish in the EEZ involves the exercise of sovereign rights over conservation and management of living resources,... and that it will do so even if the rights of other states are thereby terminated."³¹⁹

Nor, for the United Kingdom, does it matter if the MPA is characterized as environmental in nature, as "almost any modern fisheries conservation and management measure will serve... multiple objectives".³²⁰ "We can characterise the ban on fishing in the MPA as 'environmental,'" the United Kingdom submits, "but it does not follow that it therefore ceases to be about conservation and management of living resources, or that the environmental purpose prevails over the conservation and management purpose for jurisdictional purposes, or that it falls outside the very broad terms of Article 297(3)(a)."³²¹

"[T]aken as a whole," Mauritius submits, Article "297(3) provides that fisheries disputes are within a tribunal’s jurisdiction unless they fall within the categories of disputes that are excluded."³²² Even if the Tribunal does not accept that the MPA is an environmental measure, for which Article 297(1)(c) would apply, this Tribunal has jurisdiction because the exclusions in Article 297(3) "do not apply here."³²³

In applying Article 297(3), Mauritius distinguishes between the effect of the provision on the sovereign rights of the coastal State and the rights of third States in the exclusive economic zone. According to Mauritius:

The dispute is not based on the purported sovereign rights of the UK as a coastal State in relation to the living resources in the EEZ. That is not how the dispute should be characterized. As Mauritius has shown in its written pleadings, and emphasized in these oral pleadings, the dispute concerns the rights of Mauritius, this includes its right to fish in the EEZ of the Chagos Archipelago; its right to be consulted about matters that can affect its interests; its right to have fulfilled the undertaking given by Prime Minister Brown to Prime Minister Ramgoolam. It is these rights—the rights of Mauritius —that are at issue. For that reason, even if the dispute were to be characterized as a fishing dispute, it would not fall within the exception to jurisdiction located in 297(3). That exception, as the text makes unmistakably clear, pertains only to disputes relating to the rights of a coastal State; it does not concern disputes relating to the rights of other States in the EEZ arising under rules of international law.³²⁴

In Mauritius’ view, this division mirrors the distinction in Article 56 between the rights of the coastal State and the rights of other States, and there is, accordingly, "a correlation between Article 56 and 297."³²⁵ Within Article 56, Mauritius submits:

Subparagraph (1)(a) concerns a coastal State’s "sovereign rights," including sovereign rights for the purpose of conserving and managing living resources. Jurisdiction in the EEZ, on the other hand, is addressed in subparagraph (1)(b), including specifically "jurisdiction" concerning "the protection and preservation of the marine environment," as set out in subparagraph (1)(b)(iii).

Article 297(3)’s exclusion mentions only sovereign rights. It does not mention jurisdiction. This must have been deliberate. When the drafters of 297 intended a jurisdictional clause to cover both "jurisdiction" and "sovereign rights," they did so expressly. [...] This, we submit, is a clear indication that the drafters intended only disputes over "sovereign rights" under Article 56(1)(a) to be covered by the exclusion. Disputes relating to "jurisdiction" under 56(b)(iii) were not. The latter category of disputes thus falls within the general grant of jurisdiction over fisheries disputes, not the exclusion.³²⁶

Moreover, according to Mauritius, the exclusion in Article 297(3) does not apply to procedural obligations such as those that Mauritius has alleged in respect of the obligation to consult in Articles 63 and 64 of the Convention and Article 7 of the 1995 Fish Stocks Agreement. In support of this position, Mauritius relies on the award of the tribunal in Barbados/Trinidad and Tobago (Award of 11 April 2006, PCA Award Series, p. 1, RIAA, Vol. XXVII, p. 147) and the separate opinion in Southern Bluefin Tuna ((New Zealand v. Japan, Australia v. Japan), Award of 4 August 2000, Separate Opinion Of Justice Sir Kenneth Keith, RIAA, Vol. XXIII, p. 49), both of which, according to Mauritius, proceeded to consider Articles 63 and 64 on the grounds that there was no bar to jurisdiction.³²⁷

In its final submissions, Mauritius claims that the MPA is incompatible with Articles 63 and 64 of the Convention, as well as Article 7 of the 1995 Fish Stocks Agreement.

Article 63 provides as follows:

Article 63

Stocks occurring within the exclusive economic zones of two or more coastal States or both within the exclusive economic zone and in an area beyond and adjacent to it

1. Where the same stock or stocks of associated species occur within the exclusive economic zones of two or more coastal States, these States shall seek, either directly or through appropriate subregional or regional organizations, to agree upon the measures necessary to coordinate and ensure the conservation and development of such stocks without prejudice to the other provisions of this Part.

2. Where the same stock or stocks of associated species occur both within the exclusive economic zone and in an area beyond and adjacent to the zone, the coastal State and the States fishing for such stocks in the adjacent area shall seek, either directly or through appropriate subregional or regional organizations, to agree upon the measures necessary for the conservation of these stocks in the adjacent area.

Article 64 provides as follows:

Article 64

Highly migratory species

1. The coastal State and other States whose nationals fish in the region for the highly migratory species listed in Annex I shall cooperate directly or through appropriate international organizations with a view to ensuring conservation and promoting the objective of optimum utilization of such species throughout the region, both within and beyond the exclusive economic zone. In regions for which no appropriate international organization exists, the coastal State and other States whose nationals harvest these species in the region shall cooperate to establish such an organization and participate in its work.

2. The provisions of paragraph 1 apply in addition to the other provisions of this Part.

Article 7 of the 1995 Fish Stocks Agreement provides as follows:

Compatibility of conservation and management measures

1. Without prejudice to the sovereign rights of coastal States for the purpose of exploring and exploiting, conserving and managing the living marine resources within areas under national jurisdiction as provided for in the Convention, and the right of all States for their nationals to engage in fishing on the high seas in accordance with the Convention:

(a) with respect to straddling fish stocks, the relevant coastal States and the States whose nationals fish for such stocks in the adjacent high seas area shall seek, either directly or through the appropriate mechanisms for cooperation provided for in Part III, to agree upon the measures necessary for the conservation of these stocks in the adjacent high seas area;

(b) with respect to highly migratory fish stocks, the relevant coastal States and other States whose nationals fish for such stocks in the region shall cooperate, either directly or through the appropriate mechanisms for cooperation provided for in Part III, with a view to ensuring conservation and promoting the objective of optimum utilization of such stocks throughout the region, both within and beyond the areas under national jurisdiction.

2. Conservation and management measures established for the high seas and those adopted for areas under national jurisdiction shall be compatible in order to ensure conservation and management of the straddling fish stocks and highly migratory fish stocks in their entirety. To this end, coastal States and States fishing on the high seas have a duty to cooperate for the purpose of achieving compatible measures in respect of such stocks. In determining compatible conservation and management measures, States shall:

(a) take into account the conservation and management measures adopted and applied in accordance with article 61 of the Convention in respect of the same stocks by coastal States within areas under national jurisdiction and ensure that measures established in respect of such stocks for the high seas do not undermine the effectiveness of such measures;

(b) take into account previously agreed measures established and applied for the high seas in accordance with the Convention in respect of the same stocks by relevant coastal States and States fishing on the high seas;

(c) take into account previously agreed measures established and applied in accordance with the Convention in respect of the same stocks by a subregional or regional fisheries management organization or arrangement;

(d) take into account the biological unity and other biological characteristics of the stocks and the relationships between the distribution of the stocks, the fisheries and the geographical particularities of the region concerned, including the extent to which the stocks occur and are fished in areas under national jurisdiction;

(e) take into account the respective dependence of the coastal States and the States fishing on the high seas on the stocks concerned; and

(f) ensure that such measures do not result in harmful impact on the living marine resources as a whole.

3. In giving effect to their duty to cooperate, States shall make every effort to agree on compatible conservation and management measures within a reasonable period of time.

4. If no agreement can be reached within a reasonable period of time, any of the States concerned may invoke the procedures for the settlement of disputes provided for in Part VIII.

5. Pending agreement on compatible conservation and management measures, the States concerned, in a spirit of understanding and cooperation, shall make every effort to enter into provisional arrangements of a practical nature. In the event that they are unable to agree on such arrangements, any of the States concerned may, for the purpose of obtaining provisional measures, submit the dispute to a court or tribunal in accordance with the procedures for the settlement of disputes provided for in Part VIII.

6. Provisional arrangements or measures entered into or prescribed pursuant to paragraph 5 shall take into account the provisions of this Part, shall have due regard to the rights and obligations of all States concerned, shall not jeopardize or hamper the reaching of final agreement on compatible conservation and management measures and shall be without prejudice to the final outcome of any dispute settlement procedure.

7. Coastal States shall regularly inform States fishing on the high seas in the subregion or region, either directly or through appropriate subregional or regional fisheries management organizations or arrangements, or through other appropriate means, of the measures they have adopted for straddling fish stocks and highly migratory fish stocks within areas under their national jurisdiction.

8. States fishing on the high seas shall regularly inform other interested States, either directly or through appropriate subregional or regional fisheries management organizations or arrangements, or through other appropriate means, of the measures they have adopted for regulating the activities of vessels flying their flag which fish for such stocks on the high seas.

The United Kingdom objects to the Tribunal’s jurisdiction over Mauritius’ claims in relation to straddling and highly migratory fish stocks on four grounds:

- First, the United Kingdom argues that none of the relevant provisions specify "international rules or standards", such that "Article 297(1)(c)... cannot provide a jurisdictional foundation for them."³²⁸

- Second, according to the United Kingdom, Article 297(3)(a) bars jurisdiction over measures relating to straddling and highly migratory stocks in the exclusive economic zone. On this basis, the United Kingdom notes, the tribunal in Barbados/Trinidad and Tobago "found that disputes about straddling fish stocks in adjacent EEZs were outside their jurisdiction."³²⁹

- Third, "Mauritius has the burden of proving... that Mauritian vessels fish in high seas areas adjacent to the BIOT MPA or in the same region," absent which "it has no standing to invoke a dispute".³³⁰ According to the United Kingdom, Mauritius has offered evidence only of fishing within BIOT waters.³³¹

- Finally, insofar as Mauritius’ claim relates to a failure to cooperate with the Indian Ocean Tuna Commission (the "IOTC"), the United Kingdom notes that the Agreement for the Establishment of the Indian Ocean Tuna Commission³³² (the "IOTC Agreement") includes its own procedure for the settlement of disputes involving a conciliation commission, followed by recourse to the Convention or to the ICJ. According to the United Kingdom, Mauritius’ failure to initiate a conciliation commission precludes jurisdiction as Article 282 of the Convention gives priority to jurisdiction under other agreements providing for the binding resolution of disputes. Alternatively, the United Kingdom submits that jurisdiction would also be precluded by Article 281 (applicable where an agreement between the Parties excludes any further procedure) following the reasoning of the Tribunal in the Southern Bluefin Tuna arbitration.³³³

Mauritius submits that it does have standing to assert claims in relation to straddling and highly migratory fish stocks:

The UK does not deny that the relevant stocks occur within the EEZ of both the Chagos Archipelago (assuming quod non the UK is the coastal State) and Mauritius, for purposes of 63(1). Mauritius is also a "State fishing for stocks" in an area adjacent to the Chagos Archipelago’s EEZ in the sense of 63(2).³³⁴

Mauritius relies, in this respect, on the records of the IOTC Scientific Committee regarding the issuance of Mauritian tuna licenses, and submits that there is no authority for the United Kingdom’s suggestion that such fishing is located too far away from the Chagos Archipelago.³³⁵

At the same time, Mauritius rejects the proposition that the dispute resolution provisions of the IOTC Agreement pose any bar to this Tribunal’s jurisdiction. First, Mauritius notes, it "has not made any claims under the IOTC Agreement; all of its claims are based upon breaches of UNCLOS or the 1995 Fish Stocks Agreement."³³⁶ Equally important, however, Mauritius emphasizes, the IOTC Agreement does not provide for the mandatory submission of disputes to a binding procedure: "Disputes are initially referred to conciliation, which Article XXIII takes pains to say is 'not binding in character.' If conciliation does not settle the dispute, the Parties 'may'—but are not required to—refer the dispute to the ICJ."³³⁷ On its face, Mauritius argues, the criteria for exclusion in Article 282 are not met. As for Article 281, Mauritius endorses the separate opinion of Judge Keith in Southern Bluefin Tuna, to the effect that "[t]he requirement is that the Parties have agreed to exclude any further procedure for the settlement of the dispute concerning UNCLOS.... They require opting out. They do not require that the Parties positively agree to the binding procedure by opting in."³³⁸

With respect to the application of Article 297(3)(a) to straddling stocks and highly migratory species,³³⁹ Mauritius raises three arguments:

(a) First, "297(1)(c) and 297(3) are independent grounds for exercising jurisdiction" and the dispute is properly characterized as "the UK’s contravention of specified international rules or standards for the protection and preservation of the marine environment".³⁴⁰

(b) Second, "[t]he dispute is not based on the purported sovereign rights of the UK as a coastal State in relation to the living resources in the EEZ"; instead "the dispute concerns the rights of Mauritius."³⁴¹

(c) Third, relying on Judge Keith’s separate opinion in Southern Bluefin Tuna, "[p]rocedural obligations of consultation and cooperation under [Article 63, Article 64, or Article 7 of the 1995 Agreement] fall outside the 297(3) exclusion."³⁴²

In its final submissions, Mauritius claims that the MPA is incompatible with Articles 2(3) and 56(2) of the Convention, insofar as the Lancaster House Undertakings give Mauritius rights in the territorial sea and exclusive economic zone of the Chagos Archipelago.

Article 2(3) provides as follows:

Article 2

Legal status of the territorial sea, of the air space over the territorial sea and of its bed and subsoil

[...]

3. The sovereignty over the territorial sea is exercised subject to this Convention and to other rules of international law.

Article 56(2) provides as follows:

Article 56

Rights, jurisdiction and duties of the coastal State in the exclusive economic zone

[...]

2. In exercising its rights and performing its duties under this Convention in the exclusive economic zone, the coastal State shall have due regard to the rights and duties of other States and shall act in a manner compatible with the provisions of this Convention.

[...]

The United Kingdom objects to the jurisdiction of the Tribunal in respect of Mauritius’ claimed rights to fish in the territorial sea of the Chagos Archipelago on the grounds that "a dispute concerning the status and interpretation of a fisheries access agreement is not a dispute concerning interpretation and application of UNCLOS unless there is a provision for dispute settlement meeting the terms of Article 288(2) of UNCLOS."³⁴³ No such provision exists. In the United Kingdom’s view, this bar cannot be evaded by incorporating the undertaking giving Mauritius fishing rights into Article 2(3) itself. For the United Kingdom, "whether the alleged agreement is viewed separately from Article 2(3) or as part of Article 2(3), there must still be provision for dispute settlement in accordance with Article 288(2) in order for that dispute about a fisheries access agreement to fall within Part XV jurisdiction."³⁴⁴

Similarly, the United Kingdom argues with respect to Article 56(2) that "an agreement on access to EEZ stocks is... subject to compulsory jurisdiction only if it so provides in accordance with Article 288(2)."³⁴⁵ Any other interpretation would be contrary to State practice in the area of fisheries access agreements.³⁴⁶

In sum, the United Kingdom concludes:

Mauritius and the United Kingdom never agreed to any mechanism to settle disputes with respect to Mauritian fishing in the territorial sea or in the waters out to 200 nm, and UNCLOS Part XV cannot now be invoked to solve that omission or the legal consequences that flow from it.³⁴⁷

Mauritius submits that a dispute over Mauritian fishing rights in the territorial sea exists by virtue of the subjection in Article 2(3) of sovereignty over the territorial sea to other rules of international law. Mauritius contends that by extinguishing the Lancaster House Undertakings, the United Kingdom acted in contravention of such other rules of international law. According to Mauritius, the Tribunal’s jurisdiction is then "plainly established" by the simple fact that "none of the exceptions to jurisdiction that the drafters of the Convention adopted in Articles 297 and 298 are applicable such as to exclude the Tribunal’s jurisdiction in relation to a dispute under Article 2(3)."³⁴⁸

Mauritius rejects the suggestion that, in respect of the territorial sea, it has not raised a dispute concerning the interpretation or application of the Convention, but only of the Lancaster House Undertakings. Among the disputes directly relating the Convention, Mauritius identifies the following:

Does Article 2(3) impose upon the UK an obligation to respect 'other rules of international law' in exercising its purported sovereignty over the Territorial Sea around the Chagos Archipelago? Do those 'rules of international law' encompass the obligation to respect, for example, recognized fishing rights, or the obligation to respect legally binding undertakings? Has the UK breached Article 2(3) by failing to respect those rules of international law?³⁴⁹

Mauritius considers the link to the interpretation and application of the Convention to be selfevident and notes that the Parties are in agreement on the permissibility of applying other rules of international law where—as in Article 2(3)—the Convention provides an express renvoi.³⁵⁰

Mauritius similarly rejects the idea that Article 288(2) limits the Tribunal’s jurisdiction. According to Mauritius:

Article 288(2) applies only to cases submitted pursuant to the provisions of a dispute settlement clause of an international agreement other than the Convention itself. Mauritius’ claims were not submitted in accordance with the dispute settlement provisions of any other agreement. They were submitted by Mauritius in accordance with the dispute settlement provisions of Part XV of the Convention itself, invoking the Tribunal’s jurisdiction expressly under Article 288(1), because they arise directly under various substantive articles of the Convention, including Article 2(3), whose interpretation or application is clearly called for.³⁵¹

Mauritius raised claims that the MPA breached Article 78 of the Convention in its pleadings but did not include such a claim in its final submissions.

Article 78 provides as follows:

Article 78

Legal status of the superjacent waters and air space and the rights and freedoms of other States

1. The rights of the coastal State over the continental shelf do not affect the legal status of the superjacent waters or of the air space above those waters.

2. The exercise of the rights of the coastal State over the continental shelf must not infringe or result in any unjustifiable interference with navigation and other rights and freedoms of other States as provided for in this Convention.

The United Kingdom objects to the Tribunal’s jurisdiction over any claim regarding an alleged right to seabed minerals and sedentary species on the grounds that this "requires interpretation of the understanding reached in 1965, an issue that falls outside the scope of [the Tribunal's] jurisdiction under Article 288 of the Convention".³⁵² Additionally, the United Kingdom submits that there is no evidence that Mauritian nationals have ever harvested sedentary species.

According to Mauritius, "[t]here can be no doubt about the jurisdiction of this Tribunal."³⁵³ "Nothing in Article 297," Mauritius submits, "excludes from your jurisdiction the dispute over the right to harvest sedentary species on the Continental Shelf. The 297(3) exclusion applies only to the EEZ, it does not apply to the Continental Shelf."³⁵⁴

Additionally, Mauritius argues, "it was immaterial that Mauritius did not exploit sedentary species in 1965, since the undertaking was intended to 'safeguard' Mauritius’ future uses of the sea. It was not the intention that Mauritius would be forever constrained by its 1965 fishing practices."³⁵⁵

In its final submissions, Mauritius claims that the MPA is incompatible with Article 194 of the Convention, which provides in relevant part as follows:

Article 194

Measures to prevent, reduce and control pollution of the marine environment

1. States shall take, individually or jointly as appropriate, all measures consistent with this Convention that are necessary to prevent, reduce and control pollution of the marine environment from any source, using for this purpose the best practicable means at their disposal and in accordance with their capabilities, and they shall endeavour to harmonize their policies in this connection.

[...]

4. In taking measures to prevent, reduce or control pollution of the marine environment, States shall refrain from unjustifiable interference with activities carried out by other States in the exercise of their rights and in pursuance of their duties in conformity with this Convention.

[...]

The United Kingdom objects to any claim regarding Article 194 on the grounds that "[a]t present the MPA involves no new laws or policies on marine pollution."³⁵⁶ In any event, the United Kingdom argues, "although Article 194 is undoubtedly concerned with protection and preservation of the marine environment, it does not constitute the 'specified international rules and standards’ whose contravention comes within [the Tribunal's] jurisdiction under Article 297(1)(c)".³⁵⁷

According to Mauritius, the United Kingdom "concedes that Article 194 is a provision relevant to the protection and preservation of the marine environment," that would fall under Article 297(1)(c).³⁵⁸ The only objection to jurisdiction left to it is to claim that no dispute exists.³⁵⁹

Mauritius contends that this is wrong on the facts as the Parties disagree as to whether the MPA is an environmental or a fisheries measure, and that therefore "there is plainly a dispute over the interpretation or application of Article 194 over which [the Tribunal] may exercise jurisdiction."³⁶⁰ Mauritius summarizes its position as follows:

The United Kingdom does not argue it is excluded by 297. Its only argument is that the UK has not yet enacted new laws or regulations on marine pollution. The UK seems to be saying there will be jurisdiction, but not yet. [...] Article 194(1) obligates States to "endeavour to harmonize their policies" in connection with marine pollution. This is an obligation that, self-evidently, attaches prior to the enactment of such rules since it is concerned with the development of regulatory policies. The UK avers that the BIOT administration is drafting these laws, so the dispute is ripe.³⁶¹

In its final submissions, Mauritius claims that the MPA is incompatible with Article 300 of the Convention, which provides as follows:

Article 300

Good faith and abuse of rights

States Parties shall fulfil in good faith the obligations assumed under this Convention and shall exercise the rights, jurisdiction and freedoms recognized in this Convention in a manner which would not constitute an abuse of right.

According to the United Kingdom, the Parties agree that -

this Tribunal would have jurisdiction over its abuse of rights claim only to the extent that it already has jurisdiction over a dispute concerning other provisions of the Convention. So, if Article 297(1)(c) does not give you jurisdiction over the MPA declaration or the fishing ban, or if Article 297(3)(a) excludes jurisdiction, then there is likewise no jurisdiction over the related article 300 claim.³⁶²

The United Kingdom submits, however, that "[t]he core of Mauritius’ case on abuse of rights is the denial of fishing rights, and the Convention has its own special regime for abuse of rights claims in that context—that’s Article 297(3)(b)... [which] mandates compulsory conciliation as the remedy for abuse of coastal State rights over fishing."³⁶³ Mauritius has not requested conciliation and the United Kingdom considers its Article 300 claim to have been foreclosed by this separate regime.

According to Mauritius:

Article 300 establishes an independent obligation under the Convention and, to that extent, it is an independent basis of the claim. What the Convention requires, as construed by the tribunal in the Virginia case, is that the abuse be linked with the exercise of one of the substantive rights provided in the Convention.³⁶⁴

The Tribunal considers that the question of its jurisdiction over Mauritius’ Fourth Submission— concerning the compatibility of the MPA with the Convention—hinges on the characterization of the Parties’ dispute and on the interpretation and application of Article 297.

As set out above, Mauritius contends that the MPA is a measure "for the protection and preservation over the marine environment" and bases the Tribunal’s jurisdiction on Article 297(1)(c) of the Convention. The United Kingdom, in turn, contends that the MPA is an exercise of "its sovereign rights with respect to the living resources of the exclusive economic zone" and argues that the Tribunal’s jurisdiction is precluded by Article 297(3)(a). The Parties thus differ sharply in their interpretation of the factual record and their characterization of the MPA.

As set out above (see paragraph 208), it is for the Tribunal to characterize the dispute dividing the Parties. In so doing, the Tribunal considers that it is essential to evaluate both the scope of the MPA, as the measure complained of, and the scope of the rights that Mauritius alleges have been violated.

Turning first to the characterization of the MPA, the Tribunal does not accept that the MPA is solely a measure relating to fisheries. While in these proceedings the United Kingdom has sought, at times, to characterize the MPA as relating only to fisheries, noting its suspension of commercial fishing licences, the United Kingdom has justified the measure in far broader terms. In the Public Consultation preceding the decision to create the MPA, the United Kingdom FCO answered the question of "what would be the added value of creating a marine protected area?" as follows:

There is sufficient scientific information to make a convincing case for designating most of the Territory as a marine protected area (MPA), to include not only protection for fish-stocks but also to strengthen conservation of the reefs and land areas.

[...]

There is high value to scientific/environmental experts in having a minimally perturbed scientific reference site, both for Earth system science studies and for regional conservation management.

[...]

MPA designation for BIOT would safeguard around half the high quality coral reefs in the Indian Ocean whilst substantially increasing the total global coverage of MPAs. If all the BIOT area were a no-take MPA, it would be the world’s largest site with that status, more than doubling global coverage with full protection.

[...]³⁶⁵

In the BIOT Proclamation No. 1, establishing the MPA, the United Kingdom described it as follows:

1. There is established for the British Indian Ocean Territory a marine reserve to be known as the Marine Protected Area, within the Environment (Protection and Preservation) Zone which was proclaimed on 17 September 2003.

2. Within the said Marine Protected Area, Her Majesty will exercise sovereign rights and jurisdiction enjoyed under international law, including the United Nations Convention on the Law of the Sea, with regard to the protection and preservation of the environment of the Marine Protected Area. The detailed legislation and regulations governing the said Marine Protected Area and the Territory will be addressed in future legislation of the Territory.

[...]³⁶⁶

The FCO Press Release of 1 April 2010, announcing the creation of the MPA, described it in similarly expansive terms:

The MPA will cover some quarter of a million square miles and its establishment will double the global coverage of the world’s oceans under protection. Its creation is a major step forward for protecting the oceans, not just around BIOT itself, but also throughout the world.

This measure is a further demonstration of how the UK takes its international environmental responsibilities seriously.

The territory offers great scope for research in all fields of oceanography, biodiversity and many aspects of climate change, which are core research issues for UK science.³⁶⁷

In these proceedings the United Kingdom has sought to justify the MPA by submitting scientific writings describing its purpose as follows:

the Chagos/BIOT MPA was not primarily initiated as a fisheries management tool, rather to conserve the unique and rich biodiversity of this region, both in the coastal and pelagic realm. The relatively pristine nature of the coral reefs of Chagos/BIOT is particularly important considering the 2008 Status of the World’s coral reefs report reporting 19% of the original global coral reef area has already been lost through direct human impacts, with a further 15% seriously threatened within 10-20 years, and another 20% under threat in 2040 years. These predictions do not take into account the accelerating problem of climate change on the oceans. There remains a critically urgent need for more effective management that conserves remaining coral reefs, particularly those in areas of low anthropogenic pressure and thus likely to be most resilient to climate change impacts.³⁶⁸

Finally, before this Tribunal, the Attorney-General of the United Kingdom defended the MPA on the basis of its broad environmental benefits:

We are committed to furthering biodiversity of the oceans, and we believe that one significant way of doing this is through the establishment of marine protected areas.

[...]

The BIOT MPA is a regionally and internationally critical step in beginning to address the risk of irreversible damage to the oceans. It has substantially increased the global coverage of MPAs. [That] [t]he scientific case for the BIOT MPA is robust actually hasn't been challenged in this case at all. The waters around British Indian Ocean Territory are some of the most pristine in the Indian Ocean, indeed on the planet, and have a genuinely worldwide importance: scientists agree it is an exceptional place and merits protection.³⁶⁹

Having argued for the necessity and importance of the MPA by reference to environmental concerns that extend well beyond the management of fisheries, it is not now open to the United Kingdom to limit the jurisdiction of this Tribunal with the argument that the MPA is merely a fisheries measure. The Tribunal is entitled to hold the United Kingdom to the manner in which it has characterized the MPA in these proceedings and in numerous public pronouncements. The Tribunal also notes that the initiation of this arbitration, only nine months after the declaration of the MPA, may well have delayed the introduction of further implementing measures. In any event, the UK’s declared object and purpose of the MPA are certainly relevant to Mauritius, a country with a reversionary interest in the area.

The Tribunal now turns to the rights that Mauritius’ alleges to have been violated.

Mauritius contends that the MPA is incompatible with the United Kingdom’s obligations under Articles 2, 55, 56, 63, 64, 194, and 300 of the Convention, as well as Article 7 of the 1995 Fish Stocks Agreement.³⁷⁰ Among these provisions, Articles 2(3) and 56(2), regarding the exercise of sovereignty or sovereign rights over the territorial sea and exclusive economic zone, respectively, make reference to "other rules of international law" or an obligation to "have due regard to the rights and duties of other States". These provisions require the Tribunal to consider Mauritius’ legal rights as they otherwise arise as a matter of international law, as well as Mauritius’ rights arising under the Convention. Articles 63, 64, and 194, in contrast, create obligations on the United Kingdom, arising entirely within the Convention itself, to consult with other States regarding certain fisheries measures and regarding the harmonization of measures in respect of marine pollution. Article 55 describes the exclusive economic zone. Article 300 requires that the United Kingdom not exercise its rights in a manner that would constitute an abuse of rights.

For the purposes of Articles 2(3) and 56(2), the Tribunal considers the rights at issue to be those originating in the Lancaster House Undertakings made by the United Kingdom to Mauritius on 23 September 1965, in connection with the detachment of the Chagos Archipelago. As set out in detail above (see paragraphs 74-79), following that meeting Sir Seewoosagur Ramgoolam wrote to the Colonial Office, supplementing the undertakings set out in the draft record. Following the inclusion of these additions, the final minutes of the meeting record the undertakings as follows:

(i) negotiations for a defence agreement between Britain and Mauritius;

(ii) in the event of independence an understanding between the two governments that they would consult together in the event of a difficult internal security situation arising in Mauritius;

(iii) compensation totalling up to £3m. should be paid to the Mauritius Government over and above direct compensation to landowners and the cost of resettling others affected in the Chagos Islands;

(iv) the British Government would use their good offices with the United States Government in support of Mauritius’ request for concessions over sugar imports and the supply of wheat and other commodities;

(v) that the British Government would do their best to persuade the American Government to use labour and materials from Mauritius for construction work in the islands;

(vi) the British Government would use their good offices with the U.S. Government to ensure that the following facilities in the Chagos Archipelago would remain available to the Mauritius Government as far as practicable:

(a) Navigational and Meteorological facilities;

(b) Fishing Rights;

(c) Use of Air Strip for emergency landing and for refuelling civil planes without disembarkation of passengers.

(vii) that if the need for the facilities on the islands disappeared the islands should be returned to Mauritius;

(viii) that the benefit of any minerals or oil discovered in or near the Chagos Archipelago should revert to the Mauritius Government.³⁷¹

These undertakings were then conveyed to the Mauritius Council of Ministers, who were asked to indicate their agreement to the detachment of the Chagos Archipelago and did so on 5 November 1965, subject to the understanding that -

(1) statement in paragraph 6 of your despatch "H.M.G. have taken careful note of points (vii) and (viii)" means H.M.G. have in fact agreed to them.

(2) As regards (vii) undertaking to Legislative Assembly excludes

(a) sale or transfer by H.M.G. to third party or

(b) any payment or financial obligation by Mauritius as condition of return.

(3) In (viii) "on or near" means within area within which Mauritius would be able to derive benefit but for change of sovereignty. I should be grateful if you would confirm this understanding is agreed.³⁷²

Mauritius contends that these undertakings were binding as from their acceptance by the Council of Ministers and became so as a matter of international law upon the independence of Mauritius. Mauritius further contends that in declaring the MPA, the United Kingdom failed to exercise its jurisdiction subject to these undertakings (Article 2) and failed to give due regard to them (Article 56). For the purposes of determining its jurisdiction, however, the Tribunal’s concern is with the scope and character of the rights that Mauritius alleges to have been violated. The existence and binding nature of these alleged rights are matters for the merits that the Tribunal will address subsequently (see paragraphs 417-456 below). For present purposes, the Tribunal needs only to satisfy itself that the rights asserted by Mauritius are such as to justify the provisional conclusion that they may have been binding as a matter of international law and relevant to the application of Articles 2 and 56 (Interhandel Case, Judgment of March 21st 1959: I.C.J. Reports 1959, p. 6 at p. 24; see also Ambatielos case (merits: obligation to arbitrate), Judgment of May 19th, 1953: I.C.J. Reports 1953, p. 10 at p. 18). Having reviewed the role of the undertakings in the Mauritian Ministers’ agreement to the detachment of the Archipelago, the Tribunal finds that this test is satisfied.

Among the undertakings made by the United Kingdom, the Tribunal notes that (vi)(b), relating to fishing rights; (vii), relating to the return of the Archipelago when no longer needed for defence purposes; and (viii), relating to the benefit of oil and mineral resources, are potentially implicated by the declaration of the MPA. The United Kingdom’s undertaking with respect to fishing rights is clearly related to living resources and—insofar as it applies to the exclusive economic zone—falls under the exclusion from jurisdiction set out in Article 297(3)(a). In this respect, the Tribunal does not accept Mauritius’ argument that a distinction can be made between disputes regarding the sovereign rights of the coastal State with respect to living resources, and disputes regarding the rights of other States in the exclusive economic zone (with only the former excluded from compulsory settlement). In nearly any imaginable situation, a dispute will exist precisely because the coastal State’s conception of its sovereign rights conflicts with the other party’s understanding of its own rights. In short, the two are intertwined, and a dispute regarding Mauritius’ claimed fishing rights in the exclusive economic zone cannot be separated from the exercise of the United Kingdom’s sovereign rights with respect to living resources.

The United Kingdom’s remaining undertakings, however, are evidently broader. In the Tribunal’s view, the United Kingdom’s undertaking to return the Chagos Archipelago to Mauritius gives Mauritius an interest in significant decisions that bear upon the possible future uses of the Archipelago. Mauritius’ interest is not simply in the eventual return of the Chagos Archipelago, but also in the condition in which the Archipelago will be returned. In this respect, the question of whether the Archipelago will or will not be covered by an MPA in the potentially extended period prior to its return significantly affects the nature of what Mauritius will eventually receive and the uses Mauritius will be able to make of it. The Tribunal does not accept the United Kingdom’s argument that the MPA is irrelevant to the return of the Archipelago merely because the applicable regulations could potentially be undone. As the record of diplomatic correspondence in these proceedings amply demonstrates, the creation of the MPA was a significant political decision. If it were to remain and be developed over the course of many years, it could well become impractical or impolitic for Mauritius to adopt a radically different course. In short, the MPA’s very existence bears upon the choices that Mauritius will have open to it when the Archipelago is eventually returned. In a like manner, the Tribunal considers that the benefit of the minerals and oil in the surrounding waters, which Mauritius will receive when the Archipelago is returned, may be significantly affected by the MPA, in particular in light of the expansive objective of environmental protection declared by the United Kingdom.

Turning now to Mauritius’ rights to consultation and coordination pursuant to Articles 63, 64, and 194 of the Convention and Article 7 of the 1995 Fish Stocks Agreement, the Tribunal notes that the rights Mauritius claims to have been violated are not dependent on undertakings by the United Kingdom, but arise directly from the Convention itself. Articles 63 and 64 of the Convention, and Article 7 of the 1995 Fish Stocks Agreement, apply wherever the nationals of another State fish for straddling or highly-migratory fish stocks. Meanwhile, Article 194(1) imposes an obligation to "endeavour to harmonize" policies on pollution of the marine environment whenever joint action is "appropriate".

The Tribunal accepts that Articles 63 and 64 (as well as the 1995 Fish Stocks Agreement) are, on their face, measures in respect of fisheries and in their application in the exclusive economic zone are subject to the exclusion in Article 297(3)(a) (see Arbitration between Barbados and the Republic of Trinidad and Tobago, Award of 11 April 2006, PCA Award Series, p. 121, RIAA, Vol. XXVII, p. 147 at p. 226, para. 283). As set out above, the Tribunal does not accept that a distinction can be made between disputes in the exclusive economic zone over sovereign rights and those over the rights of another State (see paragraph 297). The Tribunal also finds no basis, in either Barbados/Trinidad and Tobago or Southern Bluefin Tuna (including the Separate Opinion) for the proposition that the exclusion in Article 297(3) does not apply to procedural obligations. In Barbados/Trinidad and Tobago, that tribunal expressly held that it had it no jurisdiction to establish a right of access for Barbadian fisherman in Trinidadian waters precisely because Article 297(3) applied. That tribunal went on to address the straddling flying fish stocks and Article 63 of the Convention only to the extent of "draw[ing] attention to certain matters that are necessarily entailed by the boundary line that [the Tribunal] has drawn" and of recording certain commitments made by Trinidad and Tobago during the hearing (Award of 11 April 2006, PCA Award Series, pp. 122-124, RIAA, Vol. XXVII, p. 147 at pp. 226-228, paras. 284-293). Southern Bluefin Tuna, in turn, involved a dispute over catch allowances for highly migratory species applicable "principally in the high seas" ((New Zealand v. Japan, Australia v. Japan), Award of 4 August 2000, RIAA, Vol. XXIII, p. 1 at p. 8, para. 21). Neither the Award nor the Separate Opinion make any suggestion that the jurisdictional exclusion in the exclusive economic zone pursuant to Article 297(3) was potentially applicable, nor is Japan recorded as having raised any objection on this basis.

Finally, the Tribunal is aware of the view, advanced in certain academic settings, that Article 297(3) should be construed narrowly in its application to Article 63 and Article 64 and to the 1995 Fish Stocks Agreement on the grounds that the entire purpose of the special regime for these species is to enable populations to be managed as a unified whole, and that this object and purpose is potentially frustrated by providing distinct dispute resolution regimes for such species in the exclusive economic zone and in the high seas. However desirable this purpose may be as a matter of policy, the Tribunal can see no textual basis for such a construction in either the Convention or the 1995 Fish Stocks Agreement. The latter agreement afforded ample opportunity to remedy any ambiguity of drafting in the earlier Convention, but nevertheless expressly provides that "Article 297, paragraph 3, of the Convention applies also to this Agreement" (Agreement for the Implementation of the Provisions of the United Nations Convention on the Law of the Sea of 10 December 1982 relating to the Conservation and Management of Straddling Fish Stocks and Highly Migratory Fish Stocks (with annexes), Art. 31, 4 August 1995, 2167 UNTS p. 3).

Article 194, however, is not so limited. The Tribunal notes that the United Kingdom’s objection with respect to this final provision is merely that no dispute exists as the obligation would apply only in the event the MPA were to include new regulations on marine pollution. This, however, is a defence on the merits, and not a bar to the Tribunal’s jurisdiction.

Finally, Mauritius has invoked Articles 55 and 300. Article 55 is principally concerned with the definition of the exclusive economic zone and, in the Tribunal’s view, adds nothing to the scope of the rights that Mauritius has already asserted pursuant to Article 56 and the Lancaster House Undertakings. With respect to Article 300 and the abuse of rights, the Tribunal agrees with the Parties that a claim pursuant to Article 300 is necessarily linked to the alleged violation of another provision of the Convention. As such, the nature of Mauritius’ rights pursuant to this provision coincides with the nature of the other provisions allegedly violated.

The Tribunal therefore concludes that neither the MPA nor the rights asserted by Mauritius are limited to the living resources of the exclusive economic zone. The Tribunal finds that the dispute between the Parties in relation to the compatibility of the MPA with the Convention relates more broadly to the preservation of the marine environment and to the legal regime applicable to the Archipelago and its surrounding waters when it is eventually returned to Mauritius. The Tribunal’s consideration of Mauritius’ Fourth Submission cannot therefore be excluded entirely by the exception from jurisdiction set out Article 297(3)(a). This is particularly the case in light of the extensive focus by the United Kingdom on the protection of coral, a sedentary species expressly excluded from the regime for the exclusive economic zone by Article 68 of the Convention and therefore beyond any possible application of Article 297(3)(a). The Tribunal also emphasizes that all of the rights of a coastal State, inherent in the United Kingdom’s undertaking to return the Archipelago to Mauritius, are potentially implicated and entitled to due regard pursuant to Article 56(2). In the Tribunal’s view, the Parties’ dispute cannot, as a whole, be dismissed as a fisheries matter.

Having thus addressed the objection to jurisdiction made by the United Kingdom on the basis of Article 297(3)(a), the Tribunal now turns to the relationship between its jurisdiction and Article 297(1)(c).

In the sections that follow, the Tribunal will first examine the relationship between Article 288(1) and Article 297(1) and will determine which provision founds the Tribunal’s jurisdiction in the present case. The Tribunal will then go on to consider the applicability of Article 297(1)(c) to the MPA.

Within the structure of the Part XV dispute settlement provisions of the Convention, Article 288(1) (contained in section 2 of Part XV) grants the Tribunal jurisdiction generally with respect to "any dispute concerning the interpretation or application of this Convention which is submitted to it in accordance with this Part." Article 297, although captioned "Limitations on applicability of section 2", then goes on to grant the Tribunal jurisdiction specifically over certain categories of disputes relating to sovereign rights, marine scientific research, and fisheries, providing that disputes relating to these matters "shall be subject to the procedures provided for in section 2" or "shall be settled in accordance with section 2". Articles 297(2) and 297(3) also impose express limitations on the jurisdiction the Tribunal may exercise with respect to marine scientific research or to fisheries. Article 297(1), however, is phrased entirely in affirmative terms and includes no exceptions to the jurisdiction the Tribunal may exercise.

Article 297(1) does not state that disputes concerning the exercise of sovereign rights and jurisdiction are only subject to compulsory settlement in the enumerated cases. And, as a matter of textual construction, the Tribunal does not consider that such a limitation can be implied. If Article 297(1) were understood to mean that a Tribunal would have jurisdiction over the exercise of sovereign rights and jurisdiction only in the specified cases, there would have been no need for Article 297(3) to expressly exclude disputes over the living resources of the exclusive economic zone: such disputes would be excluded already, by virtue of their noninclusion in the list of cases set out in Article 297(1). Similarly, if Article 297(1) were understood to include an implied "only" and to present an exclusive list of the cases over which the Tribunal could exercise jurisdiction, it would then conflict with the jurisdiction over marine scientific research recognized in Article 297(2), which in some cases will involve sovereign rights in the exclusive economic zone. Textually, therefore, Article 297(1) reaffirms, but does not limit, the Tribunal’s jurisdiction pursuant to Article 288(1). In light, however, of the apparent ambiguity of including a jurisdiction-affirming provision in an article otherwise devoted to limitations on the exercise of compulsory dispute settlement, the Tribunal considers it useful to delve deeper into the history of this provision.

The Tribunal recalls that the negotiations over the provision that ultimately became Article 297 of the Convention were marked by differences over the scope of compulsory dispute settlement in the exclusive economic zone. Many coastal States sought to limit or exclude compulsory settlement in order to protect their newly won jurisdiction from the expense and burden of potentially frequent challenge. Others considered comprehensive provisions for compulsory dispute settlement to be essential to the preservation of the rights of other States in the expansive areas being incorporated into the exclusive economic zone.³⁷³ In attempting to balance these competing interests, the text of what became Article 297 underwent a series of substantial revisions that dramatically changed its structure and content.

In the 1976 draft of the Convention, the Tribunal notes, what became Article 297 did provide that compulsory dispute resolution would only apply to the three cases now set out in Article 297(1).³⁷⁴ Following textual revisions in the course of that year, the provision read as follows:

1. Disputes relating to the exercise by a coastal State of sovereign rights, exclusive rights or exclusive jurisdiction recognized by the present Convention shall be subject to the procedures specified in section 2 only in the following cases:

(a) When it is claimed that a coastal State has acted in contravention of the provisions of the present Convention in regard to the freedom of navigation or overflight or of the laying of submarine cables and pipelines and other internationally lawful uses of the sea related to navigation or communication; or

(b) When it is claimed that any State, in exercising the aforementioned freedoms, has acted in contravention of the provisions of the present Convention or of laws or regulations enacted by the coastal State in conformity with the present Convention and other rules of international law not incompatible with the present Convention; or

(c) When it is claimed that a coastal State has acted in contravention of specified international standards or criteria for the preservation of the marine environment or for the conduct of marine scientific research, which are applicable to the coastal State and which have been established by the present Convention or by a competent international authority acting in accordance with the present Convention; or

(d) When it is claimed that a coastal State has manifestly failed to comply with specified conditions established by the present Convention relating to the exercise of its rights or performance of its duties in respect of living resources, provided that in no case shall the sovereign rights of the coastal State be called in question.

2. Any dispute excluded by paragraph 1 may be submitted to the procedure specified in section 2 only with the express consent of the coastal State concerned.

3. Any disagreement between the parties to a dispute as to the applicability of this article shall be decided in accordance with paragraph 3 of article 10 [now 288].³⁷⁵

At that time, no express exception was included with respect to either marine scientific research or fisheries.

In the 1977 draft of the Convention, this provision was substantially modified. Reflecting the concern with the abuse of legal process and the possibility of frequent, frivolous challenges to the jurisdiction of the coastal State, the 1977 draft provided that any dispute involving the exercise of sovereign rights or jurisdiction would be subject to certain mandatory procedural safeguards. Compulsory dispute settlement was no longer expressly restricted to the three cases now set out in Article 297(1); instead, jurisdiction in the three cases was made conditional on the fulfilment of the procedural safeguards. New exclusions were also introduced with respect to marine scientific research and fisheries. Finally, the draft Article provided in paragraph (5) that any dispute excluded from the other paragraphs could be submitted to compulsory settlement "only by agreement of the parties to such dispute". As restructured, the draft Article read as follows:

1. Without prejudice to the obligations arising under section 1, disputes relating to the exercise by a coastal State of sovereign rights or jurisdiction provided for in the present Convention shall only be subject to the procedures specified in the present Convention when the following conditions have been complied with:

(a) that in any dispute to which the provisions of this article apply, the court or tribunal shall not call upon the other party or parties to respond until the party which has submitted the dispute has established prima facie that the claim is well founded;

(b) that such court or tribunal shall not entertain any application which in its opinion constitutes an abuse of legal process or is frivolous or vexatious; and

(c) that such court or tribunal shall immediately notify the other party to the dispute that the dispute has been submitted and such party shall be entitled, if it so desires, to present objections to the entertainment of the application.

2. Subject to the fulfillment of the conditions specified in paragraph 1, such court or tribunal shall have jurisdiction to deal with the following cases:

(a) When it is alleged that a coastal State has acted in contravention of the provisions of the present Convention in regard to the freedoms and rights of navigation or overflight or of the laying of submarine cables and pipelines and other internationally lawful uses of the sea specified in article 58; or

(b) When it is alleged that any State in exercising the aforementioned freedoms, rights or uses has acted in contravention of the provisions of the present Convention or of laws or regulations established by the coastal State in conformity with the present Convention and other rules of international law not incompatible with the present Convention; or

(c) When it is alleged that a coastal State has acted in contravention of specified international rules and standards for the protection and preservation of the marine environment which are applicable to the coastal State and which have been established by the present Convention or by a competent international organization or diplomatic conference acting in accordance with the present Convention.

3. No dispute relating to the interpretation or application of the provisions of the present Convention with regard to marine scientific research shall be brought before such court or tribunal unless the conditions specified in paragraph 1 have been fulfilled; provided that:

(a) when it is alleged that there has been a failure to comply with the provision of articles 247 [now 246] and 254 [now 253], in no case shall the exercise of a right or discretion in accordance with article 247, or a decision taken in accordance with article 254, be called in question; and

(b) the court or tribunal shall not substitute its discretion for that of the coastal State.

4. No dispute relating to the interpretation or application of the provisions of the present Convention with regard to the living resources of the sea shall be brought before such court or tribunal unless the conditions specified in paragraph 1 have been fulfilled; provided that:

(a) when it is alleged that there has been a failure to discharge obligations arising under articles 61, 62, 69 and 70, in no case shall the exercise of a discretion in accordance with articles 61 and 62 be called in question; and

(b) the court or tribunal shall not substitute its discretion for that of the coastal State; and

(c) in no case shall the sovereign rights of a coastal State be called in question.

5. Any dispute excluded by the previous paragraphs may be submitted to the procedures specified in section 2 only by agreement of the parties to such dispute.³⁷⁶

In the 1979 draft, this provision was restructured yet again, and the procedural safeguards that had been a condition to the exercise of jurisdiction over the cases now set out in Article 297(1) were broken off as separate articles, eventually to become Article 294 (Preliminary Proceedings) and Article 300 (Abuse of Rights) of the final Convention. The revised draft Article on limitations to compulsory dispute settlement still provided in its final paragraph, however, that "any dispute excluded by the previous paragraphs may be submitted to the procedures specified in section 2 only by agreement of the parties to such dispute." In its 1979 form, the provision that became Article 297 thus read as follows:

1. Notwithstanding the provisions of article 286, disputes relating to the interpretation or application of this Convention with regard to the exercise by a coastal State if [ sic ] its sovereign rights or jurisdiction provided for in this Convention, shall be subject to the procedures specified in this section in the following cases.

(a) When it is alleged that a coastal State has acted in contravention of the provisions of this Convention in regard to the freedoms and rights of navigation or overflight or of the laying of submarine cables and pipelines and other internationally lawful uses of the sea specified in article 58; or

(b) When it is alleged that any State in exercising the aforementioned freedoms, rights or uses has acted in contravention of the provisions of this Convention or of laws or regulations established by the coastal State in conformity with this Convention and other rules of international law not incompatible with this Convention; or

(c) When it is alleged that a coastal State has acted in contravention of specified international rules and standards for the protection and preservation of the marine environment which are applicable to the coastal State and which have been established by this Convention or by a competent international organization or diplomatic conference acting in accordance with this Convention.

2. No dispute relating to the interpretation or application of the provisions of this Convention with regard to marine scientific research shall be brought before such court or tribunal unless the conditions specified in article have been fulfilled; provided that:

(a) when it is alleged that there has been a failure to comply with the provision of articles 246 and 253, in no case shall the exercise of a right or discretion in accordance with article 246, or a decision taken in accordance with article 253, be called in question; and

(b) the court or tribunal shall not substitute its discretion for that of the coastal State.

3. (a) Unless otherwise agreed or decided by the parties concerned, disputes relating to the interpretation or application of the provisions of this Convention with regard to fisheries shall be settled in accordance with this section, except that the coastal State shall not be obliged to accept the submission to such settlement of any dispute relating to its sovereign rights with respect to the living resources in the exclusive economic zone or their exercise, including its discretionary powers for determining the allowable catch, its harvesting capacity, the allocation of surpluses to other States and the terms and conditions established in its conservation and management regulations.

(b) Where no settlement has been reached by recourse to the provisions of section 1, a dispute shall, notwithstanding article 284, paragraph 3, be submitted to the conciliation procedure provided for in annex IV, at the request of any party to the dispute, when it is alleged that:

(i) a coastal State has manifestly failed to comply with its obligations to ensure through proper conservation and management measures that the maintenance of the living resources in the exclusive economic zone is not seriously endangered;

(ii) a coastal State has arbitrarily refused to determine, upon the request of another State, the allowable catch and its capacity to harvest the living resources with respect to stocks which that other State is interested in fishing;

(iii) a coastal State has arbitrarily refused to allocate to any State, under the provisions of articles 68, 69 and 70 and under the terms and conditions established by the coastal State consistent with this Convention, the whole or part of the surplus it has declared to exist.

(c) In any case the conciliation commission shall not substitute its discretion for that of the coastal State.

(d) The report of the conciliation commission shall be communicated to the appropriate global, regional or sub-regional intergovernmental organizations.

(e) In negotiating agreements pursuant to articles 69 and 70 the parties, unless they otherwise agree, shall include a clause on measures which the parties shall take in order to minimize the possibility of a disagreement concerning the interpretation or application of the agreement, and on how the parties should proceed if a disagreement nevertheless arises.

4. Without prejudice to the provisions of paragraph 3, any dispute excluded by the previous paragraphs may be submitted to the procedures specified in section 2 only by agreement of the parties to such dispute.³⁷⁷

In the 1980 revisions of the draft negotiating text, the provision underwent a final, major revision when the text in respect of marine scientific research was substantially re-written and the procedure for the compulsory conciliation of disputes relating to marine scientific research and fisheries was introduced.³⁷⁸ The provision was moved to the newly created section 3 and renumbered as draft Article 297. At the same time, the ultimate paragraph restricting jurisdiction over any dispute "excluded by the previous paragraphs" was deleted.³⁷⁹ As redrafted, the nearly final 1980 text of Article 297 read as follows:

1. Disputes relating to the interpretation or application of this Convention with regard to the exercise by a coastal State of its sovereign rights or jurisdiction provided for in this Convention, shall be subject to the procedures specified in section 2 in the following cases:

(a) When it is alleged that a coastal State has acted in contravention of the provisions of this Convention in regard to the freedoms and rights of navigation or overflight or of the laying of submarine cables and pipelines and other internationally lawful uses of the sea specified in article 58; or

(b) When it is alleged that any State in exercising the aforementioned freedoms, rights or uses has acted in contravention of the provisions of this Convention or of laws or regulations established by the coastal State in conformity with this Convention and other rules of international law not incompatible with this Convention; or

(c) When it is alleged that a coastal State has acted in contravention of specified international rules and standards for the protection and preservation of the marine environment which are applicable to the coastal State and which have been established by this Convention or by a competent international organization or diplomatic conference acting in accordance with this Convention.

2. (a) Disputes relating to the interpretation or application of the provisions of this Convention with regard to marine scientific research shall be settled in accordance with section 2, except that the coastal State shall not be obliged to accept the submission to such settlement any dispute arising out of:

(i) the exercise by the coastal State of a right or discretion in accordance with article 246; or

(ii) a decision by the coastal State to order suspension or cessation of a research project in accordance with article 253.

(b) Disputes arising from an allegation by the researching State that with respect to a specific project the coastal State is not exercising its rights under articles 246 and 253 in a manner compatible with the provisions of this Convention shall be submitted, at the request of either party, to the conciliation procedure specified in section 2 of annex V, provided that the conciliation commission shall not call in question the exercise by the coastal State of its discretion to designate specific areas as referred to in paragraph 6 of article 246 or of its discretion to withhold consent in accordance with paragraph 5 of article 246.

3. (a) Disputes relating to the interpretation or application of the provisions of this Convention with regard to fisheries shall be settled in accordance with section 2, except that the coastal State shall not be obliged to accept the submission to such settlement of any dispute relating to its sovereign rights with respect to the living resources in the exclusive economic zone or their exercise, including its discretionary powers for determining the allowable catch, its harvesting capacity, the allocation of surpluses to other States and the terms and conditions established in its conservation and management regulations;

(b) Where no settlement has been reached by recourse to the provisions of section 1, a dispute shall be submitted to the conciliation procedure specified in section 2 of annex V, at the request of any party to the dispute, when it is alleged that:

(i) a coastal State has manifestly failed to comply with its obligations to ensure through proper conservation and management measures that the maintenance of the living resources in the exclusive economic zone is not seriously endangered;

(ii) a coastal State has arbitrarily refused to determine, upon the request of another State, the allowable catch and its capacity to harvest the living resources with respect to stocks which that other State is interested in fishing;

(iii) a coastal State has arbitrarily refused to allocate to any State, under the provisions of articles 62, 69 and 70 and under the terms and conditions established by the coastal State consistent with this Convention, the whole or part of the surplus it has declared to exist.

(c) In any case the conciliation commission shall not substitute its discretion for that of the coastal State;

(d) The report of the conciliation commission shall be communicated to the appropriate international organizations;

(e) In negotiating agreements pursuant to articles 69 and 70 the parties, unless they otherwise agree, shall include a clause on measures which the parties shall take in order to minimize the possibility of a disagreement concerning the interpretation or application of the agreement, and on how the parties should proceed if a disagreement nevertheless arises.³⁸⁰

The Tribunal considers this extended recitation of the history of Article 297 to be warranted for the light it sheds on the intent of a provision that, as drafted, remains far from clear. In the Tribunal’s view, two propositions follow from the long evolution of Article 297. First, a limitation on the submission to compulsory settlement of disputes involving the exercise by a coastal State of its sovereign rights or jurisdiction in cases other than those set out in Article 297(1) was contemplated—originally in the exclusive formulation of that provision in 1976, and then in the catch-all final paragraph of the 1977 and 1979 draft Articles—but was omitted from the final text. The evolution and eventual disappearance of this restriction is noted in the Commentary, which observes that "the restrictive word 'only,' which appeared in earlier drafts of article 297, paragraph 1, and was moved to the abuse of legal process paragraph in 1977, was omitted in the final text of article 297, paragraph 1."³⁸¹ The Commentary further posits the change was linked to the addition of express limitations for fisheries and marine scientific research.³⁸²

Second, the placement of the jurisdiction affirming Article 297(1) within an Article devoted to limitations on the compulsory settlement of disputes is explained by the procedural safeguards that were briefly introduced into the Article and which ultimately became Article 294. Article 297(1) thus imposes a "limitation" on the compulsory settlement of disputes in the enumerated cases insofar as Article 294 permits a party to seek a preliminary determination, in advance of other procedures, that the application constitutes an abuse of legal process or is prima facie unfounded. Article 297(1) is thus not without effect within the jurisdictional structure of the Convention.

The Tribunal also notes that, in certain respects, Article 297(1) expands the jurisdiction of a Tribunal over the enumerated cases beyond that which would follow from the application of Article 288(1) alone. In addition to describing disputes relating to the interpretation and application of the Convention itself, each of the three specified cases in Article 297(1) includes a renvoi to sources of law beyond the Convention itself:

(a) Article 297(1)(a) establishes jurisdiction "in regard to other internationally lawful uses of the sea specified in article 58" and Article 58, in turn, provides that "other pertinent rules of international law" apply to the conduct of third States in the exclusive economic zone.

(b) Article 297(1)(b) establishes jurisdiction over the exercise of freedoms, rights, and uses of the sea "in contravention of... the laws and regulations adopted by the coastal State in conformity with this Convention and other rules of international law not incompatible with this Convention".

(c) Article 297(1)(c) establishes jurisdiction over acts "in contravention of specified international rules and standards for the protection and preservation of the marine environment", including those established "through a competent international organization or diplomatic conference".

Article 297(1) thus expressly expands the Tribunal’s jurisdiction to certain disputes involving the contravention of legal instruments beyond the four corners of the Convention itself and ensures that such disputes will not be dismissed as being insufficiently related to the interpretation and application of the Convention.

The Tribunal considers that the drafting history confirms the conclusion it reached from the textual construction of Article 297. Article 297(1) reaffirms a tribunal’s jurisdiction over the enumerated cases and (through Article 294) imposes additional safeguards; it does not restrict a tribunal from considering disputes concerning the exercise of sovereign rights and jurisdiction in other cases. Where a dispute concerns "the interpretation or application" of the Convention, and provided that none of the express exceptions to jurisdiction set out in Article 297(2) and 297(3) are applicable, jurisdiction for the compulsory settlement of the dispute flows from Article 288(1). It is not necessary that the Parties’ dispute also fall within one of the cases specified in Article 297(1).

In the present case, Mauritius has directly alleged that the MPA violates certain articles of the Convention. Accordingly, having determined that the exclusion of disputes relating to the living resources of the exclusive economic zone in Article 297(3)(a) does not prevent the Tribunal from considering Mauritius’ Fourth Submission, and considering that a dispute over the MPA’s alleged violation of specific articles of the Convention is a dispute concerning the interpretation or application of the Convention, the Tribunal determines that its jurisdiction is established by Article 288(1).

As set out the preceding section, the Tribunal considers that its jurisdiction is established by Article 288(1), except with respect to those portions of the Fourth Submission that the Tribunal considered subject to Article 297(3). For the sake of completeness, however, the Tribunal notes that it is also of the view that the dispute concerning Mauritius’ Fourth Submission falls within the class of disputes identified in Article 297(1)(c). Properly characterized, the Tribunal considers that the Parties’ dispute in respect of the MPA relates to the preservation of the marine environment and that Mauritius has alleged a violation of international rules and standards in this area. Article 297(1)(c) expressly reaffirms the application of compulsory settlement to such disputes.

In reaching this conclusion, the Tribunal rejects the suggestion that either Article 297(1)(c) or Part XII of the Convention (relating to the protection and preservation of the marine environment) are limited to measures aimed at controlling marine pollution. While the control of pollution is certainly an important aspect of environmental protection, it is by no means the only one. Far from equating the preservation of the marine environment with pollution control, the Tribunal notes that Article 194(5) expressly provides that -

The measures taken in accordance with this Part shall include those necessary to protect and preserve rare or fragile ecosystems as well as the habitat of depleted, threatened or endangered species and other forms of marine life.

Notably, in the Tribunal’s view, this provision offers a far better fit with the MPA as presented by the United Kingdom than its characterization as a fisheries measure.

Neither can the Tribunal accept the proposition that Article 297(1)(c) was intended to refer only to external conventions such as MARPOL, SOLAS, or the London Convention. Although the Tribunal considers that Article 297(1) sets out a further grant of jurisdiction over disputes relating the contravention of the standards elaborated in such conventions (see paragraph 316 above), it remains the case that Article 297(1)(c) also expressly refers to "rules and standards... established by this Convention."

Finally, the Tribunal is unconvinced that the reference to "international rules and standards" in Article 297(1)(c) was intended to refer only to substantive rules and standards, and cannot therefore include the obligation to consult with or give due regard to the rights of other States. As a general matter, the Tribunal has little difficulty with the concept of procedural constraints on State action, and notes that such procedural rules exist elsewhere in international environmental law, for instance in the general international law requirement to carry out an environmental impact assessment in advance of large scale construction projects (see Indus Waters Kishenganga Arbitration (Pakistan v. India), Partial Award of 18 February 2013, PCA Award Series, p. 81 at pp. 291-292, para. 450; Pulp Mills on the River Uruguay (Argentina v. Uruguay), Judgment, I.C.J. Reports 2010, p. 14 at p. 83, para. 205). Such procedural rules may, indeed, be of equal or even greater importance than the substantive standards existing in international law. In the Tribunal’s view, the obligation to consult with and have regard for the rights of other States, set out in multiple provisions of the Convention, is precisely such a procedural rule and its alleged contravention is squarely within the terms of Article 297(1)(c).

For the foregoing reasons, the Tribunal concludes that it has jurisdiction pursuant to Article 288(1), and Article 297(1)(c), to consider Mauritius’ Fourth Submission and the compatibility of the MPA with the following provisions of the Convention:

(a) Article 2(3) insofar as it relates to Mauritius’ fishing rights in the territorial sea or to the United Kingdom’s undertakings to return the Archipelago to Mauritius when no longer needed for defence purposes and to return the benefit of any minerals or oil discovered in or near the Chagos Archipelago to Mauritius;

(b) Article 56(2), insofar as it relates to the United Kingdom’s undertakings to return the Archipelago to Mauritius when no longer needed for defence purposes and to return the benefit of any minerals or oil discovered in or near the Chagos Archipelago to Mauritius;

(c) Article 194; and

(d) Article 300, insofar as it relates to the abuse of rights in connection with a violation of one of the foregoing articles.

In its final submissions, Mauritius requests the Tribunal to declare that -

the United Kingdom shall take no steps that may prevent the Commission on the Limits of the Continental Shelf from making recommendations to Mauritius in respect of any full submission that Mauritius may make to the Commission regarding the Chagos Archipelago under Article 76 of the Convention;

Article 76 of the Convention defines the continental shelf and provides in relevant part as follows:

Article 76

Definition of the continental shelf

[...]

8. Information on the limits of the continental shelf beyond 200 nautical miles from the baselines from which the breadth of the territorial sea is measured shall be submitted by the coastal State to the Commission on the Limits of the Continental Shelf set up under Annex II on the basis of equitable geographical representation. The Commission shall make recommendations to coastal States on matters related to the establishment of the outer limits of their continental shelf. The limits of the shelf established by a coastal State on the basis of these recommendations shall be final and binding.

[...]

Mauritius submits that a dispute concerning the interpretation or application of Article 76(8) of the Convention "is a dispute which is plainly within the jurisdiction of this tribunal."³⁸³

According to Mauritius, there is "a dispute between the Parties as to whether or not Mauritius has standing under that article to submit information to the CLCS in respect of the Chagos Archipelago area. The resolution of that dispute requires that the Tribunal interpret or apply Article 76(8)."³⁸⁴ Alternatively, Mauritius submits that -

Another way to look at it is that there is a dispute as to whether the filing by Mauritius was effective, whether or not the clock has stopped, and whether or not Mauritius can make a full submission. There is thus a dispute as to whether the conditions exist for the CLCS to give effect to its role under Article 76(8) and Annex 2 in relation to Mauritius and the Chagos Archipelago. This is not an exhaustive list. But it is more than sufficient, [...] to establish [...] jurisdiction in regard to the issues raised under Article 76(8).³⁸⁵

Mauritius concludes that "[d]isputes concerning rights in the Continental Shelf, including the Extended Continental Shelf, are not subject to any of the exclusions of section 3 of Part XV. A fortiori the Tribunal has jurisdiction to resolve the aspects of this dispute that concern Article 76(8)."³⁸⁶

The United Kingdom objects to the Tribunal’s jurisdiction on the grounds that -

there can be no basis whatsoever for Mauritius’ new final submission (3), [...]. Even if this new claim were within the scope of the Notification and Statement of Claim, which [...] it is not, there is no way that Mauritius can show that it has complied with the requirements of section 1 of Part XV, in particular, article 283.³⁸⁷

The United Kingdom argues further as follows:

The dispute that Mauritius brought up [...] over delineation is just a reiteration of the same underlying sovereignty dispute [...]. Mauritius is just saying that there is a dispute as to Article 76(8) because it is the coastal State entitled to submit information under that article. That just adds another provision to the current dispute. It makes no difference whatsoever to the jurisdictional hurdles that Mauritius faces, and likewise does not impact on the fact that Mauritius’ form of mixed dispute has nothing whatsoever to do with maritime delimitation.³⁸⁸

The Tribunal notes that Mauritius’ Third Submission did not feature in the Notification and Statement of Claim. At the hearings, Mauritius explained³⁸⁹ that it had added this submission in response to the following statement in the United Kingdom’s Rejoinder :

In accordance with the terms of article 76(7), only the coastal State may delineate the outer limits of the continental shelf. In accordance with article 76(8), only the coastal State may submit information to the CLCS on the limits of the shelf beyond 200 nautical miles. Mauritius is not the coastal State in respect of BIOT and as such it has no standing before the CLCS with respect to BIOT.³⁹⁰

In assessing its jurisdiction, the Tribunal considers that it must first determine whether there is a dispute between the Parties regarding the issue addressed by Mauritius’ Third Submission. In order to do that, it is necessary to examine the history of the position taken by each Party regarding that issue, both before and after the commencement of arbitration proceedings on 20 December 2010.

The question of a submission to the CLCS was discussed at the Mauritius-United Kingdom Joint Meeting on 14 January 2009. There were no official minutes of that meeting but each side kept its own record and there was a Joint Communiqué issued at the end of the meeting, all of which have been put before the Tribunal. The Mauritius record deals with the prospective CLCS submission in the following terms.³⁹¹ The matter was raised by Mr Doug Wilson, an FCO legal adviser who was a member of the United Kingdom team. Mauritius records him as having said the following:

Art. 76 UNCLOS provides that a state make an application to the UN for Continental Shelf beyond 200 miles zone. UK has no interest to applying to the UN for extension. There is very little prospect for oil and gas. So reference to paragraph 22 of the 1965 letter would not be an issue.

We wanted to open a possibility to produce a joint submission to claim an extended Continental Shelf. That would require extensive scientific research and employment of qualified scientists. We can look forward for joint submissions.

Mr Suresh C. Seeballuck, the head of the Mauritian delegation, replied as follows:

With regard to Continental Shelf, we have a deadline of 13 May 2009 to make our submission. The deadline is there. We welcome your suggestion for a joint submission and possibly we have to work in earnest to achieve it. We have, on the basis of research, some basic data. We are prepared to exchange same with the UK side for the joint submission.

Mr Wilson clarified that all that was needed by 13 May 2009 was "an outline submission". In this respect, the Tribunal recalls that Article 4 of Annex II to the Convention established the procedure that -

Where a coastal State intends to establish, in accordance with article 76, the outer limits of its continental shelf beyond 200 nautical miles, it shall submit particulars of such limits to the Commission along with supporting scientific and technical data as soon as possible but in any case within 10 years of the entry into force of this Convention for that State.

In practice, it emerged that developing States would, in many instances, have difficulty in assembling the scientific and technical data required to meet the ten year deadline. On 29 May 2001, the Meeting of States Parties to the Convention took the decision that -

(a) In the case of a State Party for which the Convention entered into force before 13 May 1999, it is understood that the ten-year time period referred to in article 4 of Annex II to the Convention shall be taken to have commenced on 13 May 1999;

(b) The general issue of the ability of States, particularly developing States, to fulfil the requirements of article 4 of Annex II to the Convention be kept under review.³⁹²

On 20 June 2008, with the revised deadline approaching, the Meeting of States Parties took the following further decision that preliminary outline submissions would suffice to toll the ten year deadline:

(a) It is understood that the time period referred to in article 4 of annex II to the Convention and the decision contained in SPLOS/72, paragraph (a), may be satisfied by submitting to the Secretary-General preliminary information indicative of the outer limits of the continental shelf beyond 200 nautical miles and a description of the status of preparation and intended date of making a submission in accordance with the requirements of article 76 of the Convention and with the Rules of Procedure and the Scientific and Technical Guidelines of the Commission on the Limits of the Continental Shelf;

(b) Pending the receipt of the submission in accordance with the requirements of article 76 of the Convention and with the Rules of Procedure and the Scientific and Technical Guidelines of the Commission, preliminary information submitted in accordance with subparagraph (a) above shall not be considered by the Commission;

(c) Preliminary information submitted by a coastal State in accordance with subparagraph (a) is without prejudice to the submission in accordance with the requirements of article 76 of the Convention and with the Rules of Procedure and the Scientific and Technical Guidelines of the Commission, and the consideration of the submission by the Commission;

(d) The Secretary-General shall inform the Commission and notify member States of the receipt of preliminary information in accordance with subparagraph (a), and make such information publicly available, including on the website of the Commission;

[...]³⁹³

In the course of the Joint Meeting, Mr Roberts, the BIOT Administrator, then added:

We have no expectation of deriving any benefit from what we will get. It will flow to Mauritius when the territory will be ceded to you. It is one of the reasons why we have not invested resources to collect data. We recognize the underlying structure of this discussion. You may wish to take action and we will provide political support.

After a brief discussion, Mr Seeballuck reiterated "our willingness to join the UK on the joint submission notwithstanding our sovereignty position".

The United Kingdom record of the talks is very similar. The United Kingdom record summed up the discussion of the possible CLCS submission in the following terms:

The UK opened up the possibility of co-operating with the Mauritians, under a sovereignty umbrella, on an extended continental shelf agreement (ie., a joint submission to the Commission on the Limits of the Continental Shelf). We had no interest ourselves in seabed mineral extraction. That would be for Mauritius when we have ceded BIOT. There would be no exploration or exploitation until then. It would require much expensive scientific and research work to collect and analyse data but it could be done if both sides agreed that a joint submission was appropriate.

The Mauritian delegation welcomed the UK statement about a joint submission but was concerned that the deadline was 30 May 2009 so much work would need to be done. They already had some basic data that could help. Mauritian agreement to a joint submission would, however, be conditional upon an equitable exploitation of resources whenever they may occur.

The UK delegation clarified that all that was needed by May was an outline submission. The UK delegation reiterated that the UK had no expectation of deriving commercial or economic benefit from anything discovered on the continental shelf. Our understanding was that this would flow to Mauritius once the territory had been ceded. This was one of the reasons why the UK had not invested resources in collecting data. What we were talking about was legal and political co-operation to secure the continental shelf on the premise that it is scientifically possible to do this.

The Mauritians questioned why the UK was insisting on its position on sovereignty but prepared to accept a joint submission to the Continental Shelf? We explained that the Mauritians should not see our position as a sign of weakness or obligation. We wanted to be helpful where we could within the limits set out on sovereignty and treaty obligations. Our offers were on specific subjects we thought would be useful.³⁹⁴

The Joint Communiqué issued at the end of the talks made only a brief reference to the discussions having included the topic of the continental shelf. The Communiqué did, however, make clear that the talks had been held under a "sovereignty umbrella":

Both Governments agreed that:

nothing in the conduct or content of the present meeting shall be interpreted as:

(a) A change in the position of the United Kingdom with regard to sovereignty over the British Indian Ocean Territory/Chagos Archipelago;

(b) A change in the position of Mauritius with regard to sovereignty over the British Indian Ocean Territory/Chagos Archipelago;

(c) Recognition of or support for the position of the United Kingdom or Mauritius with regard to sovereignty over the British Indian Ocean Territory/Chagos Archipelago;

(d) No act or activity carried out by the United Kingdom, Mauritius or third parties as a consequence and in implementation of anything agreed to in the present meeting or in any similar subsequent meetings shall constitute a basis for affirming, supporting, or denying the position of the United Kingdom or Mauritius regarding sovereignty of the British Indian Ocean Territory/Chagos Archipelago.³⁹⁵

In May 2009, Mauritius filed preliminary information with the CLCS.³⁹⁶ Paragraph 6 of that document was entitled "unresolved land and maritime disputes" and stated that -

The Republic of Mauritius states that the Chagos Archipelago is and has always formed part of its territory. The Republic of Mauritius wishes to inform the Commission, however, that a dispute exists between the Republic of Mauritius and the United Kingdom over the Chagos Archipelago. Discussions are ongoing between the two governments on this matter. The last bilateral talks were held in London, United Kingdom, in January 2009.

The second round of Mauritius-United Kingdom talks took place in Port Louis on 21 July 2009. The Mauritius record of those talks (contained in a briefing document provided for the Mauritian Cabinet) described the discussion of the extended continental shelf in the following terms:

The British side proposed that Mauritius and the UK should make a joint submission to the United Nations Commission on the Limits of the Continental Shelf (CLCS) for an extended continental shelf around the Chagos Archipelago. The Mauritian side remarked that at the first round of talks, the UK did not show much interest in submitting a claim for an extension of the continental shelf. In the circumstances, Mauritius decided to make a unilateral submission to be within the deadline of 13 May 2009.

After discussions, it was agreed that although we have already made our submission within the deadline of 13 May 2009, there is scope for Mauritius and UK to work together towards a coordinated submission and that a technical committee would be set up with officials from both sides to look into the modalities of this coordinated approach.³⁹⁷

The United Kingdom record contained the following passage:

The UK delegation suggested that Mauritius and the UK could work together within the UN process to secure a claim perhaps by a coordinated submission. This could be of benefit to Mauritius because otherwise the submission would effectively be put on ice because of the sovereignty dispute. All benefits of an [extended Continental Shelf] would ultimately fall to Mauritius when BIOT was no longer required for defence purposes. Mauritius welcomed the suggestion that the UK and Mauritian teams could work together on this. The Mauritian delegation explained the reasons behind their preliminary note which flagged up their intention to lodge a submission over this area by 2012 was to ensure that they were not prejudiced by failing to meet the May 2009 deadline. The UK delegation commented that this time-frame for preparation of the submission seemed realistic. The UK delegation also explained that we were not proposing UK funding extensive analysis and surveys but could facilitate access to the technical sources and help with the legal process. It was agreed that the best way forward would be a coordinated submission under a sovereignty umbrella and that technical experts from both sides should get together. Comment: there was a need, as in the January talks, to reiterate the fact that the UK had no intention of benefiting from an [extended Continental Shelf]. Any exploitation would be for the benefit of Mauritius. Our proposal was to get an [extended Continental Shelf] established. We would then talk about the basis on which exploitation could begin. We could not define a date when BIOT will no longer be needed for defence purposes but this was one way of ensuring that the [extended Continental Shelf] could be established in principle pending the area being eventually ceded to Mauritius.³⁹⁸

The Joint Communiqué issued after the talks stated:

Both delegations were of the view that it would be desirable to have a coordinated submission for an extended continental shelf in the Chagos Archipelago/British Indian Ocean Territory region to the UN Commission on the Limits of the Continental Shelf, in order not to prejudice the interest of Mauritius in that area and to facilitate its consideration by the Commission. It was agreed that a joint technical team would be set up with officials from both sides to look into possibilities and modalities of such a coordinated approach, with a view to informing the next round of talks.³⁹⁹

As recorded above (see paragraphs 146-147), the further rounds of talks envisaged at the second round in July 2009 never took place. Nor has the joint technical team been set up.

Mauritius’ Notification and Statement of Claim referred to the issue of submissions to the CLCS only to the extent of stating that "[i]n 2009, Mauritius submitted to the United Nations Commission on the Limits of the Continental Shelf a preliminary claim to an extended continental shelf in areas beyond 200 miles from the archipelagic baselines of the Chagos Islands..."⁴⁰⁰ In its Memorial, Mauritius referred to the preliminary information which it had submitted to the CLCS and the absence of protest by the United Kingdom and argued that "the absence of protest on the part of the UK appears to be a clear recognition that Mauritius has sovereign rights in relation to the continental shelf".⁴⁰¹ The United Kingdom responded, in its Counter-Memorial, by contending that this argument was unfounded insofar as everything had been done under the sovereignty umbrella agreed upon at the first round of talks and that the CLCS Rules of Procedure expressly dealt with submissions in respect of an extended continental shelf where there was a land or maritime dispute. The United Kingdom also highlighted the fact that Mauritius had stated in its submission of preliminary information that a dispute with the United Kingdom existed in respect of the Chagos Archipelago.⁴⁰²

In its Reply, Mauritius maintained that the fact that there had been no United Kingdom submission to the CLCS, together with the absence of protest by the United Kingdom regarding Mauritius’ preliminary information, suggested an acknowledgment that Mauritius possessed rights in respect of the continental shelf around the Chagos Archipelago.⁴⁰³ Mauritius contrasted the absence of protest by the United Kingdom in this case with its protest regarding the submission made by Argentina in respect of the Falkland Islands/Islas Malvinas.⁴⁰⁴ The United Kingdom countered, in its Rejoinder, that Mauritius "cannot alter the status of the BIOT continental shelf by making its own submission to the CLCS with respect to BIOT".⁴⁰⁵ It was in this context that the United Kingdom made the comment quoted in paragraph 331 above, which Mauritius claimed at the hearings gave rise to an additional dispute between the Parties.⁴⁰⁶ Mauritius expressed its grave concern that what it considered to be a new position taken by the United Kingdom risked permanently precluding Mauritius from enjoying the benefits of an extended continental shelf.⁴⁰⁷

In response, the United Kingdom denied that there was any such dispute. It maintained that it had raised the argument set out in its Rejoinder (and the earlier argument in its Counter-Memorial) merely in order to respond to the attempt by Mauritius to invoke the filing of preliminary information and the absence of a protest by the United Kingdom as support for its claim with regard to the issues raised in Mauritius’ first two submissions.⁴⁰⁸ The United Kingdom contended that it had offered at the two rounds of bilateral talks to make a joint submission under a sovereignty umbrella, in order to avoid any risk that Mauritius would be deprived of the chance to secure an extended continental shelf and that the United Kingdom itself had no intention of securing any benefit from the establishment of an extended continental shelf. Counsel for the United Kingdom told the Tribunal:

Mauritius mischaracterises the statement in paragraph 8.39, ignoring both context and content. First, it is a single sentence forming part of a legal argument made by one party to another in the course of arbitral proceedings. As Mauritius rightly points out, the United Kingdom has not protested to the United Nations. Second, it was a statement that Mauritius itself had provoked, by its arguments in these arbitral proceedings. The UK was reacting, in the context of these legal proceedings, to Mauritius’ argument that "[t]he absence of protest on the part of the UK appears to be a clear recognition that Mauritius has sovereign rights in relation to the continental shelf."

On content, Mauritius places an absolute interpretation on the statement in the Rejoinder. It means, they say, that the submission of the Preliminary Information is a nullity; that the clock has not been stopped and cannot now be stopped. That is not the position. In any event, as the Agent said yesterday, we now hear that Mauritius may be in the position to make a full submission later this year. If so, we look forward to discussing with Mauritius how this might be taken forward. If a State puts in an objection to another State’s submission to the CLCS, that is not the end of the matter. Objections can always be lifted. In fact, the practice in the CLCS suggests that an objection can be the start of a dialogue, part of an ongoing diplomatic process between the States concerned. Moreover, the CLCS’s backlog is so great that many years are likely to elapse before the Commission would be ready to proceed to consider a new submission and the situation then might be very different. During that period it would be incumbent on the United Kingdom and Mauritius to discuss how to take the matter forward, as the Agent indicated yesterday.⁴⁰⁹

The Tribunal has reviewed this record in detail, because it considers that it was a necessary step in determining whether a separate dispute between the Parties has come into existence regarding the subject-matter of Mauritius’ Third Submission. It is not suggested that there was a dispute between Mauritius and the United Kingdom regarding the question of submissions to the CLCS prior to the filing of the Notification and Statement of Claim. On the contrary, the record of the two rounds of bilateral talks confirms that no such dispute existed at that time. Rather, Mauritius maintains that such a dispute was created by the language used by the United Kingdom in its Rejoinder (in the passage quoted above). The Tribunal considers that that passage has to be seen in the light of the exchange of legal arguments between the Parties. The United Kingdom was responding to an argument by Mauritius regarding whether Mauritius was the (or, at least, a) coastal State in respect of the Chagos Archipelago. That argument was advanced in the context of a dispute over which the Tribunal has already held that it lacks jurisdiction. The United Kingdom was not raising an objection before the CLCS. In the course of the hearings, the United Kingdom made clear that the offer of co-operation, under a sovereignty umbrella, regarding the full submission to the CLCS, which the United Kingdom had already extended at the July 2009 bilateral talks after Mauritius had filed preliminary information with the CLCS, was still open. The Tribunal considers, therefore, that there is no risk of Mauritius losing the possibility of seeking an extended continental shelf by reason of the expiry of the 13 May 2009 deadline.

In view of the willingness of the United Kingdom that the submission to the CLCS proceed under a sovereignty umbrella—a willingness which the United Kingdom expressed in both rounds of the bilateral talks and repeated in the course of the oral proceedings in the present case—and of Mauritius’ acceptance of such an approach in the bilateral talks, the Tribunal considers that there is no dispute between the Parties regarding this issue.

Accordingly, the Tribunal considers that it is not required to rule on whether it has jurisdiction over Mauritius’ third submission, nor upon the merits of that submission.

The United Kingdom further objects to the jurisdiction of the Tribunal on the grounds that, prior to initiating this arbitration, Mauritius failed to engage in the exchange of views required by Article 283(1). In the United Kingdom’s view, such an exchange is a precondition to jurisdiction under the Convention that was not met with respect to any of Mauritius’ claims.⁴¹⁰

Article 283 of the Convention provides as follows:

Article 283

Obligation to exchange views

1. When a dispute arises between States Parties concerning the interpretation or application of this Convention, the parties to the dispute shall proceed expeditiously to an exchange of views regarding its settlement by negotiation or other peaceful means.

2. The parties shall also proceed expeditiously to an exchange of views where a procedure for the settlement of such a dispute has been terminated without a settlement or where a settlement has been reached and the circumstances require consultation regarding the manner of implementing the settlement.

Mauritius submits that the requirements of Article 283(1) are plainly met as it "repeatedly raised" the subject matter of all claims in these proceedings⁴¹¹ "over several decades, in bilateral and multilateral contexts".⁴¹² In any event, Mauritius emphasizes, the requirements of Article 283 are "not onerous", and a Party is not required to continue negotiations indefinitely.

As the Tribunal has already decided that it has jurisdiction only with respect to Mauritius’ Fourth Submission, it will examine the application of Article 283 only with respect to that portion of the Parties’ dispute.

According to the United Kingdom -

Article 283, in practical terms, requires as a first step communication by one party, received by the other party which results in a shared understanding as to what the dispute or disputes are and likewise that they are under the 1982 Convention. This is implicit from the requirement that the parties exchange views over its peaceful settlement or negotiation: they must have a shared understanding about what they are talking about in order to exchange views on it.⁴¹³

This requirement, the United Kingdom submits, is not part of customary international law,⁴¹⁴ but arose instead from the particular context of the negotiations at the Third UN Conference on the Law of the Sea. It was intended both to ensure that States would not be taken by surprise by the introduction of binding dispute settlement procedures, and "to allow a State to rectify any possible wrongdoing or violation of the [Convention] prior to the initiation of an interstate dispute."⁴¹⁵ While this requirement may be unusual, the United Kingdom considers it to have been an essential part of the overall bargain in the Convention, as "[t]he requirement for prior attempts to settle disputes without recourse to compulsory procedures was seen as a central element in the negotiations that led to the acceptance of Part XV by the Conference."⁴¹⁶ Compulsory jurisdiction under Article 286, the United Kingdom submits, is thus contingent upon compliance with the provisions for settlement through non-binding means, including Article 283.

Although the United Kingdom considers Article 283 to be distinct from compromissory clauses requiring prior attempts at negotiation,⁴¹⁷ it submits that international jurisprudence reinforces the importance of such conditions to jurisdiction. The United Kingdom notes, in particular, the ICJ’s observation in Georgia v. Russia that such provisions are important to give notice to the Respondent, to encourage the parties to settle their dispute, and to limit the scope of States’ consent to dispute settlement (Application of the International Convention on the Elimination of All Forms of Racial Discrimination (Georgia v. Russian Federation), Preliminary Objections, Judgment, I.C.J. Reports 2011, p. 70 at p. 124, para. 131). The United Kingdom also recalls the ICJ’s emphasis that "[w]hen that consent is expressed in a compromissory clause in an international agreement, any conditions to which such consent is subject must be regarded as constituting the limits thereon" (Armed Activities on the Territory of the Congo (New Application: 2002) (Democratic Republic of the Congo v. Rwanda), Jurisdiction and Admissibility, Judgment, I.C.J. Reports 2006, p. 6 at p. 39, para. 88).

With respect to the specific steps required by Article 283, the United Kingdom submits that -

- There must be a "dispute" between the States Parties to the Convention;

- The dispute must concern "the interpretation or application of the Convention";

- And the parties to the dispute must have "proceeded expeditiously to an exchange of views regarding its settlement by negotiation or other peaceful means".⁴¹⁸

While the United Kingdom does not consider that such exchanges must be lengthy, it does submit that the exchange must be sufficiently clear as to put the respondent on notice and to give it "the opportunity to redress the issues and to even modify its behaviour."⁴¹⁹ Moreover, "[s]ince the exchange of views must concern the modalities of settlement of disputes," the United Kingdom considers that the requirement cannot be met "without identifying the specific treaty and provisions concerned, since the range of settlement means available will depend upon the provisions at issue."⁴²⁰

Mauritius submits that -

the requirements of Article 283 are not particularly onerous. They form a threshold jurisdictional requirement to ensure that parties are not taken by surprise by the initiation of proceedings, but they do not require lengthy exchanges, they do not require reference to specific treaties or provisions, and the State’s judgment as to when to terminate exchanges will be accorded considerable respect. This is an area where the law is concerned with substance, not with form.⁴²¹

According to Mauritius, each of these propositions is supported in prior international jurisprudence. First, Mavrommatis Palestine Concessions provides that "[n]egotiations do not of necessity always presuppose a more or less lengthy series of notes and dispatches; it may suffice that a discussion should have commenced, and this discussion may have been very short" (Mavrommatis Palestine Concessions, Jurisdiction, Judgment of 30 August 1924, PCIJ Series A, No. 2, p. 6 at p. 13). Second, Guyana v. Suriname (Award of 17 September 2007, PCA Award Series, 158-159, RIAA, Vol. XXX, p. 1 at p. 113-114, paras. 407-410) and Land Reclamation by Singapore in and around the Straits of Johor ((Malaysia v. Singapore), Provisional Measures, Order of 8 October 2003, ITLOS Reports 2003, p. 10) (in the context of Article 283), and Georgia v. Russia (generally) stand for the proposition that "it is not necessary that a State must expressly refer to a specific treaty in its exchanges with the other State"⁴²² (Application of the International Convention on the Elimination of All Forms of Racial Discrimination (Georgia v. Russian Federation), Preliminary Objections, Judgment, I.C.J. Reports 2011, p. 70 at p. 84, para. 30). Finally, Land Reclamation and Mavrommatis both support the view that a State is "not obliged to continue with an exchange of views when it concludes that the possibilities of reaching agreement have been exhausted" (Land Reclamation by Singapore in and around the Straits of Johor (Malaysia v. Singapore), Provisional Measures, Order of 8 October 2003, ITLOS Reports 2003, p. 10 at para. 47) and further that "States themselves are 'in the best position to judge as to political reasons which may prevent the settlement of a given dispute' [ Mavrommatis Palestine Concessions, Jurisdiction, Judgment of 30 August 1924, PCIJ Series A, No. 2, p. 6 at p. 15]".⁴²³

According to Mauritius, the United Kingdom seeks to read into Article 283 requirements that are nowhere to be found in the accumulated case law. When it insists that an exchange of views must make specific reference to the Convention, Mauritius argues, the United Kingdom "ignore[s] the clear words of the International Court in Georgia v. Russia".⁴²⁴ And in limiting what it considers to be relevant exchanges to a narrow window of time, Mauritius considers the United Kingdom to have adopted an overly formalistic approach and neglected to examine the record as a whole.⁴²⁵

In sum, Mauritius concludes, the jurisprudence on the application of Article 283 indicates that it imposes a hurdle of only "very modest height" that can be "stepped over lightly," "[s]o long as the applicant can produce some evidence of relevant exchanges."⁴²⁶

The United Kingdom submits that Mauritius has not met the requirements of Article 283 in respect of its Fourth Submission, relating to the compatibility of the MPA with the Convention and the alleged breach of undertakings made by the United Kingdom. According to the United Kingdom, "there is nowhere any Statement from Mauritius that challenges the legality of MPA on the basis of UNCLOS provisions x, y, and z, and then concludes with an invitation to discuss some form of exchange of views. And there is nothing in this record that could be treated as somehow of equivalent effect."⁴²⁷

Turning to the correspondence advanced by Mauritius, the United Kingdom considers that "all the documents that Mauritius relies on to establish the existence of a dispute and an exchange of views for the purposes of its breach of UNCLOS strand [of argument] concern fishing rights, which is also the principal element in [relation to the claimed breach of undertakings]."⁴²⁸ With respect to correspondence prior to 2009, the United Kingdom argues that insofar as "these communications pre-date the MPA proposal, and even the ideas of Pew and the Chagos Conservation Trust for large-scale marine park in the BIOT, a dispute about the MPA proposal or the MPA could not have been raised."⁴²⁹

Moreover, according to the United Kingdom, whenever "Mauritius responded to the various restrictions on its ability to fish over the years, it did not object on the grounds that the UK was acting in breach of UNCLOS but cast its case in terms of its sovereignty claim, which... was not with reference to UNCLOS."⁴³⁰ Reviewing Mauritius’ correspondence piece by piece, the United Kingdom concludes that it "all com[es] down to the sovereignty issue"⁴³¹ and submits that "Mauritius is unable to point to any exchange of views in relation to a claim of alleged breaches of UNCLOS."⁴³²

Mauritius divides the relevant correspondence between that pre-dating and that post-dating Mauritius learning of the MPA proposal in February 2009. Before February 2009, Mauritius argues, correspondence is relevant because it shows "Mauritius continuously asserting its rights over the Archipelago, including the fishing rights which would be brought to an end by the decision to impose a no-take MPA."⁴³³ Mauritius recalls what it describes as a "huge number of occasions on which Mauritius asserted its specific rights in the Archipelago,"⁴³⁴ including fishing rights, and concludes that "UK officials... were well aware of the fact that Mauritius had raised these specific rights".⁴³⁵

After February 2009, Mauritius points to a series of exchanges that it considers make clear its diplomatic protest against the infringement of its rights in the Chagos Archipelago. In particular, Mauritius recalls:

(a) The Joint Communiqué⁴³⁶ of the July 2009 talks between the two governments, which according to Mauritius indicates that "the Mauritian delegation made it quite clear that the proposed MPA would have to accommodate its rights in the Chagos Archipelago";⁴³⁷

(b) Mauritius’ Note Verbale of 23 November 2009, which provided as follows:

The Government of Mauritius considers that an MPA project in the Chagos Archipelago should not be incompatible with the sovereignty of the Republic of Mauritius over the Chagos Archipelago and should address the issues of resettlement, access to the fisheries resources, and the economic development of the islands in a manner which would not prejudice an eventual enjoyment of sovereignty. A total ban on fisheries exploitation and omission of those issues from any MPA project would not be compatible with the long-term resolution of, or progress in the talks, on the sovereignty issue.⁴³⁸

(c) A letter dated 30 December 2009 from the Mauritius Minister of Foreign Affairs, which provided as follows:

Moreover, the issues of resettlement in the Chagos Archipelago, access to the fisheries resources and the economic development of the islands in a manner that would not prejudice the effective exercise by Mauritius of its sovereignty over the Chagos Archipelago are matters of high priority to the Government of Mauritius. The exclusion of such important issues in any discussion relating to the proposed establishment of a Marine Protected Area would not be compatible with resolution of the issue of sovereignty over the Chagos Archipelago and progress in the ongoing talks between Mauritius and the United Kingdom.⁴³⁹

(d) A letter dated 19 February 2010 from the Secretary to Cabinet and Head of the Civil Service, which provided as follows:

I further wish to inform you that the Government of Mauritius insists that any proposal for the protection of the marine environment in the Chagos Archipelago area needs to be compatible with and meaningfully take on board the position of Mauritius on the sovereignty over the Chagos Archipelago and address the issues of resettlement and access by Mauritians to fisheries resources in that area.⁴⁴⁰

In sum, Mauritius concludes, it "made it clear that, in its view, [the MPA] would violate its substantive and procedural rights—rights which Mauritius had asserted for many years, of which the UK was fully aware, and which in many cases were self-evidently incompatible with a no-take MPA."⁴⁴¹

In addition to disagreeing as to whether the requirements of Article 283 were met, the Parties differ as to whether it would have been futile to continue negotiations.

The United Kingdom dismisses Mauritius’ arguments about the supposed futility of further talks as "pure assertion."⁴⁴² On the contrary, the United Kingdom submits, "Mauritius, according to its own pleadings, had not even sought to communicate with the United Kingdom about the MPA for over eight months between 2 April 2010 and 20 December 2010 when it submitted its Notification and Statement of Claim."⁴⁴³

To the extent that Mauritius alleges that further exchanges were futile on the basis of the United Kingdom’s failure to honour a purported undertaking by then British Prime Minister Gordon Brown to suspend the Public Consultation, the United Kingdom denies that any undertaking was made. In any event, however, the United Kingdom denies that "a failure to withdraw the public consultation could possibly make it 'clear' that any further exchanges in relation to the dispute notified in Mauritius’ application would be 'futile and without purpose'."⁴⁴⁴

According to the United Kingdom, it -

does not dispute the well-established principle that a party is not obliged to continue with an exchange of views when the possibilities of settlement have been exhausted. Its contention is that Mauritius cannot even establish that it raised the UNCLOS claims which it now raises, let alone that an exchange of views had taken place and that the possibilities of a settlement had been exhausted.⁴⁴⁵

Mauritius maintains that the British Prime Minister Gordon Brown made a commitment, in November 2009, to put the MPA on hold that was "expressed in the clearest possible terms."⁴⁴⁶ Notwithstanding this commitment the United Kingdom declared the MPA on 1 April 2010.

Mauritius identifies communications between April and November 2010⁴⁴⁷ by which it conveyed "strong opposition" to the MPA⁴⁴⁸ and raised the inadequacy of the United Kingdom’s consultation process⁴⁴⁹ and the failure of the United Kingdom to honour the assurance by former Prime Minister Gordon Brown.⁴⁵⁰

In Mauritius’ view, the "violation of the commitment given at the highest level" made it plain that "no diplomatic solution was possible" and accordingly, continuing exchanges on the issue would have been futile.⁴⁵¹ Moreover, Mauritius submits that it was entirely reasonable to consider that further exchanges after initiation of these proceedings would have been futile in view of the circumstances.⁴⁵²

As set out above, the Parties disagree both as to the interpretation of Article 283 and as to its application to Mauritius’ Fourth Submission. Mauritius’ account of its compliance with Article 283 ranges widely through the history of the Parties’ diplomatic exchanges regarding the proposed MPA. The United Kingdom, in contrast, points to the absence of a specific communication setting out a particular dispute by reference to the Convention and either proposing an approach for its resolution, or inviting an exchange of views.

In the Tribunal’s view, much of the argument on this issue has tended to confuse two related, but distinct concepts. Article 283 requires the Parties to "proceed expeditiously to an exchange of views regarding [the] settlement [of the dispute] by negotiation or other peaceful means." Article 283 thus requires the Parties to exchange views regarding the means for resolving their dispute; it does not require the Parties to in fact engage in negotiations or other forms of peaceful dispute resolution. As a matter of textual construction, the Tribunal considers that Article 283 cannot be understood as an obligation to negotiate the substance of the dispute. Read in that manner, Article 283(1) would, redundantly, require that parties "negotiate regarding the settlement of the dispute by negotiation". The Tribunal also notes that Article 283(2) requires a further exchange of views upon the failure of a dispute settlement procedure. If an exchange of views were taken to involve substantive negotiations, this would literally require that, upon the failure of negotiations, the parties must engage in negotiations: such a construction cannot be correct. Finally, the drafters of this provision saw fit to include an exhortation that the parties proceed "expeditiously" to an exchange of views. Given the clear and understandable preference among the participants at the Third UN Conference on the Law of the Sea that disputes be resolved by negotiation whenever possible, the Tribunal cannot accept that the final text could have included a provision that would have the effect of rushing, or potentially imposing a time limit on, substantive negotiations. Article 283 is thus a provision particular to the Convention and distinct from a requirement that parties engage in negotiations prior to resorting to arbitration.

The Convention includes no express requirement that parties engage in negotiations on the substance of a dispute before resorting to compulsory settlement. To the extent that such a requirement could be considered to be implied from the structure of sections 1 and 2 of Part XV, the Tribunal has no hesitation in concluding that Mauritius has met such a requirement. The Parties discussed the proposed MPA during the bilateral talks in July 2009, in diplomatic correspondence, at CHOGM, and in a number of conversations between Prime Minister Ramgoolam and Foreign Minister Boolell and the British High Commissioner in Mauritius, Mr John Murton. With respect to any obligation to carry out substantive negotiations, the Tribunal considers it to be settled international law that "it is not necessary that a State must expressly refer to a specific treaty in its exchanges with the other State to enable it later to invoke that instrument," but that "the exchanges must refer to the subject-matter of the treaty with sufficient clarity to enable the State against which a claim is made to identify that there is, or may be, a dispute with regard to that subject-matter" (Application of the International Convention on the Elimination of All Forms of Racial Discrimination (Georgia v. Russian Federation) Preliminary Objections, Judgment, I.C.J. Reports 2011, p. 70 at p. 85, para. 30; see also Military and Paramilitary Activities in and against Nicaragua (Nicaragua v. United States of America), Jurisdiction and Admissibility, Judgment, I.C.J. Reports 1984, p. 392 at pp. 428-429, para. 83). Moreover, States themselves are in the best position to determine where substantive negotiations can productively be continued, and "if finally a point is reached at which one of the Parties definitely declares himself unable, or refuses, to give way, and there can therefore be no doubt that the dispute cannot be settled by diplomatic negotiation" (Mavrommatis Palestine Concessions, Jurisdiction, Judgment of 30 August 1924, PCIJ Series A, No. 2, p. 6 at p. 13, 15). As set out in the factual record, Mauritius engaged in negotiations with the United Kingdom regarding the steps that would be taken before an MPA might be declared (see paragraphs 128-147 above). Mauritius’ decision that substantive negotiations could not continue in parallel with the United Kingdom’s Public Consultation, or that negotiations did not warrant pursuing after the MPA was declared on 1 April 2010, did not violate any duty to negotiate in respect of the Parties’ dispute.

Article 283, however, concerns an exchange of views on the means to settle the dispute, whether by negotiation or other peaceful means. In the Tribunal’s view, the most unequivocal example of compliance with this provision is that offered by Australia and New Zealand in the Southern Bluefin Tuna arbitration. In identical Notes Verbales dated 15 September 1999, Australia and New Zealand each set out a history of diplomatic communications recording the termination of negotiations, the possible submission of the dispute to mediation, Japan’s preference for arbitration under the 1993 Convention for the Conservation of Southern Bluefin Tuna, and Australia and New Zealand’s rejection of this option and intent to submit that dispute to arbitration under the Convention (Southern Bluefin Tuna (New Zealand v. Japan), Request for the Prescription of Provisional Measures Submitted by New Zealand at Annex 1, New Zealand’s Diplomatic Note 701/14/7/10/3 to Japan dated 15 July 1999, reproduced in International Tribunal for the Law of the Sea, Pleadings, Minutes of Public Sittings and Documents, Vol. 4 (1999) at p. 14; Southern Bluefin Tuna (Australia v. Japan), Request for the Prescription of Provisional Measures Submitted by Australia at Annex 1, Australia’s Diplomatic Note No. LGB 99/258 to Japan dated 15 July 1999, reproduced in International Tribunal for the Law of the Sea, Pleadings, Minutes of Public Sittings and Documents, Vol. 4 (1999) at p. 82). The United Kingdom points to the absence of a similar record of views exchanged in these proceedings and would have the Tribunal deny jurisdiction on those grounds.

The Tribunal, however, is sensitive to the concern expressed by the tribunal in Barbados/Trinidad and Tobago that an overly formalistic application of Article 283 does not accord with how diplomatic negotiations are actually carried out (Award of 11 April 2006, PCA Award Series, pp. 94-96, RIAA, Vol. XXVII, p. 147 at pp. 206-207, paras. 201-205). In practice, substantive negotiations concerning the parties’ dispute are not neatly separated from exchanges of views on the preferred means of settling a dispute, and the idealized form exhibited in Southern Bluefin Tuna will rarely occur. Accordingly, it is unsurprising that in the jurisprudence on Article 283 it is frequently not clear as to whether the communications that were considered sufficient for the purposes of Article 283 were substantive or procedural in nature.

Nevertheless, Article 283 forms part of the Convention and was intended to ensure that a State would not be taken entirely by surprise by the initiation of compulsory proceedings. It should be applied as such, but without an undue formalism as to the manner and precision with which views were exchanged and understood. In the Tribunal’s view, Article 283 requires that a dispute have arisen with sufficient clarity that the Parties were aware of the issues in respect of which they disagreed. In the present case, the Tribunal considers that a dispute regarding the manner in which the United Kingdom was proceeding with the proposed MPA had arisen at least as of Mauritius’ Note Verbale of 23 November 2009. In that communication, Mauritius set out its concern regarding the impact of the MPA on issues of sovereignty, resettlement, and fisheries. Mauritius also stated its view that these issues should be addressed in the bilateral framework between the two governments and that this should be done before the United Kingdom undertook to consult with the public:

[...]

Furthermore, the Ministry of Foreign Affairs, Regional Integration and International Trade would like to state that since there is an on-going bilateral Mauritius-UK mechanism for talks and consultations on issues relating to the Chagos Archipelago and a third round of talks is envisaged early next year, the Government of the Republic of Mauritius believes that it is inappropriate for the consultation on the proposed marine protected area, as far as Mauritius is concerned, to take place outside this bilateral framework.

The Government of Mauritius considers that an MPA project in the Chagos Archipelago should not be incompatible with the sovereignty of the Republic of Mauritius over the Chagos Archipelago and should address the issues of resettlement, access to the fisheries resources, and the economic development of the islands in a manner which would not prejudice an eventual enjoyment of sovereignty. A total ban on fisheries exploitation and omission of those issues from any MPA project would not be compatible with the longterm resolution of, or progress in the talks, on the sovereignty issue.

The stand of the Government of Mauritius is that the existing framework for talks on the Chagos Archipelago and the related environmental issues should not be overtaken or bypassed by the consultation launched by the British Government on the proposed MPA.⁴⁵³

Once a dispute has arisen, Article 283 then requires that the Parties engage in some exchange of views regarding the means to settle the dispute. As is apparent from Foreign Secretary David Miliband’s letter of 15 December 2009, the United Kingdom considered it appropriate to continue with a third round of bilateral talks in parallel with the Public Consultation:

[...]

At our meeting, you mentioned your concerns that the UK should have consulted Mauritius further before launching the consultation exercise. I regret any difficulty this has caused you or your Prime Minister in Port Louis. I hope you will recognize that we have been open about the plans and that the offer of further talks has been on the table since July.

I would like to reassure you again that the public consultation does not in any way prejudice or cut across our bilateral intergovernmental dialogue with Mauritius on the proposed Marine Protected Area. The purpose of the public consultation is to seek the views of the wider interested community, including scientists, NGOs, those with commercial interests and other stakeholders such as the Chagossians. The consultations and our plans for an MPA do not in any way impact on our commitment to cede the territory when it is no longer needed for defence purposes.

Our ongoing bilateral talks are an excellent forum for your Government to express its views on the MPA. We welcome the prospect of further discussion in the context of these talks, the next round of which now look likely to happen in January.

As well as the MPA there are, of course, many other issues for bilateral discussion. My officials remain ready to continue the talks and I hope that Mauritius will take up the opportunity to pursue this bilateral dialogue.

[...]⁴⁵⁴

Mauritius, in contrast, considered that the dispute should be resolved through bilateral talks, but that pending such talks the United Kingdom’s Public Consultation should be put on hold. This is apparent from Mauritius’ account of the conversation at CHOGM (see paragraphs 135-138 above) and, in any event, from Foreign Minister Arvin Boolell’s letter of 30 December 2009:

During our recent meeting in the margins of the Commonwealth Heads of Government Meeting, I had expressed the concerns of the Government of Mauritius about the Marine Protected Area project. I had stated that it was inappropriate for the British authorities to embark on consultations on the matter outside the bilateral Mauritius-United Kingdom mechanism for talks on issues relating to the Chagos Archipelago.

[...]

In these circumstances, as I have mentioned, Mauritius is not in a position to hold separate consultations with the team of experts of the UK on the proposal to establish a Marine Protected Area.

You will no doubt be aware that, in the margins of the last CHOGM, our respective Prime Ministers agreed that the Marine Protected Area project be put on hold and that this issue be addressed during the next round of Mauritius-United Kingdom bilateral talks.⁴⁵⁵

Although this correspondence also dealt with substantive matters (as would be expected), the Parties’ views on the settlement of the dispute by negotiation were clearly exchanged in December 2009. This is all that Article 283 requires. It is not necessary for the Parties to comprehensively canvas the means for the peaceful settlement of disputes set out in either the UN Charter or the Convention, nor was Mauritius "obliged to continue with an exchange of views when it concludes that the possibilities of reaching agreement have been exhausted" (Land Reclamation in and around the Straits of Johor (Malaysia v. Singapore), Provisional Measures, Order of 8 October 2003, ITLOS Reports 2003, p. 10 at para. 47). Nor, importantly, does Article 283 require that the exchange of views include the possibility of compulsory settlement or that—before resorting to compulsory settlement—one party caution the other regarding the possibility of litigation or set out the specific claims that it might choose to advance. In the present case, both Parties preferred to address their dispute through negotiations, albeit subject to incompatible conditions that ultimately prevented further talks from taking place. The exchange of views took place on this basis. Thereafter, Mauritius determined that the possibility of reaching agreement on the conditions for further negotiations had been exhausted and elected to proceed with compulsory settlement through arbitration. Nothing further was called for.

Accordingly, the Tribunal concludes that Mauritius has met the requirement of Article 283 to exchange views regarding the settlement, by negotiation or other peaceful means, of the dispute underpinning Mauritius’ Fourth Submission.

As set out in the preceding Chapter, the Tribunal has found that it has jurisdiction with respect to Mauritius’ Fourth Submission, requesting the Tribunal to adjudge and declare that -

(4) The United Kingdom’s purported "MPA" is incompatible with the substantive and procedural obligations of the United Kingdom under the Convention, including inter alia Articles 2, 55, 56, 63, 64, 194 and 300, as well as Article 7 of the Agreement for the Implementation of the Provisions of the United Nations Convention on the Law of the Sea of 10 December 1982 Relating to the Conservation and Management of Straddling Fish Stocks and Highly Migratory Fish Stocks of 4 August 1995.

Among the provisions of the Convention invoked by Mauritius in this submission, the Tribunal has held (see paragraph 323 above) that it has jurisdiction with respect to:

(a) Article 2(3) insofar as it relates to Mauritius’ fishing rights in the territorial sea or to the United Kingdom’s undertakings to return the Archipelago to Mauritius when no longer needed for defence purposes and to return the benefit of any minerals or oil discovered in or near the Chagos Archipelago to Mauritius;

(b) Article 56(2), insofar as it relates to the United Kingdom’s undertakings to return the Archipelago to Mauritius when no longer needed for defence purposes and to return the benefit of any minerals or oil discovered in or near the Chagos Archipelago to Mauritius;

(c) Article 194; and

(d) Article 300, insofar as it relates to the abuse of rights in connection with a violation of one of the foregoing articles.

The Tribunal will now proceed to consider the merits of the claims Mauritius has advanced pursuant to these provisions. The Tribunal will first address the content of Mauritius’ rights, both pursuant to the Convention and otherwise, in the territorial sea, exclusive economic zone, and continental shelf areas affected by the MPA. The Tribunal will then address whether the United Kingdom’s declaration of the MPA was in breach of its obligations under the aforementioned provisions of the Convention.

The Tribunal has set out the Lancaster House Undertakings made by the United Kingdom to Mauritius on 23 September 1965 (see paragraphs 74-79 above).

Mauritius contends that these undertakings were binding legal commitments and give Mauritius rights as a matter of international law, including fishing rights in the waters of the Chagos Archipelago, mineral and oil rights in the seabed and subsoil, and a right to the return of the Chagos Archipelago to Mauritius when it is no longer needed for defence purposes. The United Kingdom, in contrast, categorically denies that the undertakings could have been legally binding as a matter of British constitutional law and argues that the scope of any such rights would, in any event, be limited.

Separately, Mauritius also claims traditional fishing rights in the waters of the Chagos Archipelago. The United Kingdom does not accept that Mauritius has made out a case for the existence of such rights.

Mauritius’ primary position in these proceedings is that no valid agreement was reached in 1965 at Lancaster House or in the subsequent approval of the detachment of the Chagos Archipelago by the Mauritius Council of Ministers. According to Mauritius, the United Kingdom was in violation of its obligations with respect to self-determination, the linkage between detachment and independence imposed by the United Kingdom put the Mauritius Council of Ministers under duress, and any purported consent "was not given in accordance with the applicable standards for the treatment of a colonizer towards an independence movement."⁴⁵⁶

Nevertheless, Mauritius argues, even though there was no valid agreement, "the U.K.’s undertakings to Mauritius, all of which were repeated and expressly renewed by successive British governments over the next four and a half decades after Mauritius became an independent State, still constitute binding legal obligations."⁴⁵⁷ According to Mauritius, the binding nature of the undertakings stems not from Mauritius’ agreement to detachment, but from the fact that the United Kingdom retained the Archipelago after making them:

The United Kingdom, on independence, not after independence—on independence— retained the Archipelago. It therefore affirmed the conditions on which it had come to receive the Archipelago, even if the consent given was vitiated.

[...]

[The 1965 agreement] was not a treaty, nor was it intended as a binding arrangement under British law [...]. It was an arrangement made in the context of negotiations for independence which take some time between persons who knew what they were doing in virtue of independence.

[...]

At the very second of independence, when the excision was affirmed by the continued presence of the United Kingdom in the Archipelago, the United Kingdom disabled itself from denying the conditions attached to its presence. [...] [T]his is a situation in which the colonial authority exercising its power assumed a responsibility which it affirms not after independence, but on independence, the very second of independence, because otherwise it would have to hand the territory back. [...] [I]n the circumstances, the United Kingdom is bound by the obligations it assumed while it holds on to the territory [...].⁴⁵⁸

In the alternative, Mauritius submits that if "there was a lawful agreement on detachment of the Archipelago, then the consideration for Mauritius’ consent must include the undertakings that the United Kingdom expressly gave in exchange for it. They would then be legally binding terms of a lawful agreement under international law."⁴⁵⁹

Under either view, Mauritius argues that the applicable test is whether the United Kingdom intended to be bound by the undertakings.⁴⁶⁰ In this respect, Mauritius maintains that the contemporaneous documentary evidence -

shows that, at all times, the United Kingdom intended and considered the undertakings to be legally binding, establishing legal obligations for the U.K. and legal rights for Mauritius. This is reflected in the language and circumstances of the exchanges made at Lancaster House in September 1965 and subsequently, and in the consistent pattern of statements and actions by responsible U.K. representatives and officials, including its Legal Advisers.⁴⁶¹

Moreover, the specific undertakings were part of the quid pro quo or "package of inducements" given in exchange for what the United Kingdom regarded as Mauritius’ consent to the detachment of the Chagos Archipelago.⁴⁶² In assessing the United Kingdom’s understanding of the undertakings, Mauritius argues that the consistent internal opinions held by the United Kingdom’s own Legal Advisers "carry special weight" in assessing the United Kingdom’s intent.⁴⁶³ According to Mauritius, there is no evidence that the United Kingdom’s Legal Advisers ever held a contrary view prior to April 2010.⁴⁶⁴

In any case, Mauritius submits that the subsequent practice of the United Kingdom, in repeatedly renewing and reconfirming all of the undertakings after Mauritius’ independence and until the declaration of the MPA, confirmed the United Kingdom’s understanding of the undertakings and is itself an independent source of obligation binding on the United Kingdom.⁴⁶⁵ According to Mauritius, the United Kingdom, "having on many occasions stated that the undertaking is binding, is now estopped from claiming otherwise in these proceedings."⁴⁶⁶ Mauritius goes on to recall the Argentina-Chile Frontier Case ((Argentina v Chile), Award of 9 December 1966, R.I.A.A. Vol. XVI, p. 109, at p. 164 (1969)) and submits that -

"there is in international law a principle, which is moreover a principle of substantive law and not just a technical rule of evidence, according to which, 'a State party to an international litigation is bound by its previous acts or attitude when they are in contradiction with its claims in the litigation.'" Accordingly, "inconsistency between claims or allegations put forward by a State, and its previous conduct in connection therewith, is not admissible (allegans contraria non audiendus est)."⁴⁶⁷

In the alternative, Mauritius considers that the reaffirmation of the undertakings would "represent the repetition of undertakings under international law which are binding [on the United Kingdom] on the Nuclear Tests principle", pursuant to which unilateral declarations may be endowed with binding effect.⁴⁶⁸

Finally, Mauritius argues, the legally binding character of the United Kingdom’s undertaking with respect to fishing rights is undiminished by the inclusion in the undertaking of words to the effect that the United Kingdom would "use its good offices" to secure fishing rights.⁴⁶⁹ According to Mauritius, what the undertaking with respect to fishing rights entailed was -

a commitment to obtain for Mauritius the broadest possible fishing rights first by making best efforts to get the U.S. to consent to them and then, if successful, to establish and preserve them in the exercise of the U.K.’s own power, and that is exactly how the U.K. interpreted and understood its obligation as the contemporaneous documents show.⁴⁷⁰

In practice, which was "consistent and uninterrupted... over 45 years", Mauritius argues that this undertaking "came to be understood by both parties as the right to fish in all the BIOT waters, out to 200 miles... subject to licences issued freely by the BIOT administration to Mauritian-flagged vessels without charge."⁴⁷¹

In the course of these proceedings, the Agent for the United Kingdom set out his government’s view of what it refers to as the "1965 understandings" in the following terms:

We consider all of the understandings reached in 1965 to be important political commitments on both sides, typical of the friendship our two countries shared at the time they were given.

As to the question whether the UK could cede BIOT to a third State, our long-standing position is that the United Kingdom does not recognise the claim by Mauritius to sovereignty over the British Indian Ocean Territory. But, the United Kingdom has previously recognised Mauritius as the only State which has a right to assert a claim of sovereignty when the United Kingdom relinquishes its own sovereignty, and successive Governments have given political undertakings to the Government of Mauritius that the territory will be ceded when it is no longer required for defence purposes.⁴⁷²

The United Kingdom submits that "in assessing the status of the 1965 understandings, one needs to look not to international law, but to British law, including British constitutional law. And it is clear that under British law the understandings were not legally binding or otherwise intended to have legal effect."⁴⁷³ In this respect, the United Kingdom submits⁴⁷⁴ that -

It is not possible for overseas territories to conclude an agreement binding under international law with another overseas territory or for one or more overseas territories to conclude such an agreement with the United Kingdom. This is because internationally the Territories are not legal entities separate from each other or from the United Kingdom.⁴⁷⁵

Accordingly, the United Kingdom argues, "arrangements of this sort between, to put it at its most formal, the Crown in right of the United Kingdom and the Crown in right of the Colony of Mauritius, could not be legally binding. They were at most political understandings, not enforceable in the courts."⁴⁷⁶

In the United Kingdom’s view, in the absence of a legally binding agreement at the time the Archipelago was detached, Mauritius’ case depends upon establishing that the United Kingdom undertook a binding unilateral commitment. The United Kingdom considers the relevant standard to have been set out in the Nuclear Tests proceedings ((Australia v. France), Judgment, I.C.J. Reports 1974, p. 253; (New Zealand v. France), Judgment, I.C.J. Reports 1974, p. 457) and contends that Mauritius must "mak[e] out a case under Nuclear Tests, and... as part of requiring that there be an intention to be bound, it has to show clarity as to what the undertaking, the alleged undertaking, actually provides for."⁴⁷⁷

With respect to binding intent, the United Kingdom submits that "there never was any intention on the part of the United Kingdom to be bound by reference to what was and always has been a non-binding understanding on fishing rights."⁴⁷⁸ According to the United Kingdom, the official record of the meeting of 23 September 1965 "contains a series of understandings, not legally binding obligations".⁴⁷⁹ With respect to the matter of "fishing rights", the United Kingdom notes that this reference is preceded by the commitment to "use 'good offices'" with an object "to ensure that the... facilities would remain available";⁴⁸⁰ and the qualifier "as far as practicable".⁴⁸¹

Essentially, the United Kingdom argues, Mauritius "sought preference with respect to fishing rights to the extent such were granted, and that grant would be pursuant to domestic, not international, law".⁴⁸² Moreover, the qualifying words meant there was "no absolute obligation" but what was practicable;⁴⁸³ and "fishing rights", properly construed, is not an unqualified or unambiguous term.⁴⁸⁴

With regard to the position after independence, the United Kingdom maintains that -

any renewal of the 1965 statements post-independence would bring one back to the agreed record, as to which the criteria established in the ICJ jurisprudence and reflected in the 2006 ILC Guiding Principles would not be met, not least because there was never any intention to be bound.⁴⁸⁵

The United Kingdom does not accept that any transposition of the understandings to the international plane changes their status as "nonbinding understandings, commitments... but political commitments by each side,"⁴⁸⁶ and further argues that its own internal comments on the status of these commitments have limited legal significance,⁴⁸⁷ on which the Tribunal should be "very wary of placing weight."⁴⁸⁸

In the alternative, even accepting the existence of a binding unilateral undertaking on fishing rights, the United Kingdom contends that it is entitled to revoke this undertaking. The United Kingdom relies upon the International Law Commission (the "ILC")’s Guiding Principles Applicable to Unilateral Declarations of States Capable of Creating Legal Obligations⁴⁸⁹ (the "ILC Guiding Principles") for the proposition that international law prohibits only the arbitrary revocation of a unilateral undertaking.⁴⁹⁰ In the present circumstances, the United Kingdom submits that revocation would not have been an arbitrary step.⁴⁹¹

The Parties do not differ with respect to the content of any Mauritian rights to the return of the Chagos Archipelago when it is no longer needed for defence purposes⁴⁹² or to the benefit of minerals and oil in its surrounding waters.⁴⁹³ With respect to fishing rights, however, the Parties part company. The Parties agree that the insertion of the reference to "fishing rights" into the official record at the behest of Sir Seewoosagur Ramgoolam was not a correction of a deficient minute, but a renegotiation of the package.⁴⁹⁴ The Parties also agree that the content of this undertaking was not specifically elaborated in the official record of the Lancaster House Meeting.⁴⁹⁵ Where they disagree is on the meaning the Tribunal should accord to the reference to "fishing rights" in the United Kingdom’s undertaking.

Mauritius maintains that the undertaking given with respect to fishing rights was broad and -

translated into Mauritius’ right to have its vessels fish anywhere in the Chagos waters except in the immediate vicinity of Diego Garcia Island, and for any species, subject only to the requirement that they obtain fishing licences, which were issued freely and without charge.⁴⁹⁶

This right stems from the Lancaster House Undertakings, but its content is informed by the Parties’ subsequent practice in applying the fishing rights undertaking. Ultimately, Mauritius argues, this right to fish extended to 200 nautical miles, and is "reflected in the contemporaneous documentation, via consistent and uninterrupted subsequent practice over 45 years".⁴⁹⁷

According to Mauritius, there is no basis to limit its fishing rights to "preferential treatment" or to link them to the rights of other States.⁴⁹⁸ The only reference to "preferential treatment" with respect to fishing rights occurred early in the documentary record at a time when the Mauritian Ministers were still insisting on a long-term lease. As the Lancaster House Undertakings were ultimately developed, however, the discussion shifted to one of fishing "rights".⁴⁹⁹ Nor, in Mauritius’ view, is the content of the undertaking significantly limited by the reference to the use of "good offices" with the United States. Mauritius explains this issue as follows:

The entire purpose of detaching the Archipelago was to secure it for the establishment of the U.S. military base. The U.S. might have been concerned that expansive fishing rights for Mauritius or anyone else, for that matter, especially in close proximity to the islands, might compromise the security of the base. The U.K. [...] could not ensure Mauritius’ fishing rights without first obtaining the consent of the United States. Hence, the undertaking was to use "good offices" with the Americans to ensure fishing rights for Mauritius "as far as practicable." [...] The U.K.’s good offices were successful. The Americans agreed to the very broad array of fishing rights to Mauritius that the U.K. proposed [...]. After obtaining American consent, the U.K. then took steps directly to ensure all of these fishing rights for Mauritius exercising its powers as administrator of the "BIOT."⁵⁰⁰

Nevertheless, Mauritius argues, the inclusion of this condition does not give the United Kingdom the power to itself constrain Mauritian fishing rights. According to Mauritius,

It would make absolutely no sense, [...] to interpret the 1965 undertaking so as to obligate the U.K. to endeavor to obtain U.S. consent to Mauritian fishing rights as far as practicable but then after this consent was obtained, to allow the U.K. to unilaterally choose not to give effect to those rights or to give effect to them briefly and then immediately abolish them. That surely would have been bad faith, and that surely was not what the U.K. intended when it gave Mauritius its undertaking in regard to ensuring fishing rights as far as practicable.⁵⁰¹

Finally, Mauritius submits that its fishing rights were consistently exercised by Mauritian flagged vessels until the declaration of the MPA and were a matter of great importance.⁵⁰² Mauritius also notes that the United Kingdom continued to grant fishing licences to Mauritius even when no other State was permitted to fish.⁵⁰³

According to the United Kingdom, it is clear that the meaning of "fishing rights" in the official record of the Lancaster House Meeting was "preferential fishing rights if granted".⁵⁰⁴ In the United Kingdom’s view, the phrase is to be understood in the context of the limited fishing practices of the inhabitants of the Chagos Archipelago in 1965.⁵⁰⁵

The undertaking was not, the United Kingdom submits, "a perpetual and absolute right to all such fishing rights as could be granted as a matter of international law as it developed".⁵⁰⁶ Instead, the United Kingdom argues, "the 1965 statement on fishing rights is hedged about with soft language and qualifications, with fishing rights being described as a form of 'facility.'"⁵⁰⁷ Moreover, any subsequent attempt by Mauritius to advance an expansive interpretation of the commitment was consistently rejected by the United Kingdom.⁵⁰⁸

The United Kingdom also regards Mauritius’ lack of objection when measures impacting fishing in BIOT waters were introduced and duly notified by the United Kingdom as inconsistent with the extensive rights Mauritius now claims.⁵⁰⁹ As a matter of fact, the United Kingdom argues that Mauritians have demonstrated "minimal interest" in the exploitation of Mauritius’ fishing rights.⁵¹⁰

Mauritius submits that it possesses traditional fishing rights in the territorial sea⁵¹¹ and the exclusive economic zone⁵¹² surrounding the Chagos Archipelago. According to Mauritius, "even if the Chagos Archipelago was lawfully detached from Mauritius..., the detachment cannot render void any existing rights of access or use, or other rights related to the exploitation of natural resources."⁵¹³

The standard for such rights, Mauritius argues, is merely that they have been exercised "for many years... in the waters in question."⁵¹⁴ Moreover, in Mauritius’ view, "decades of the UK’s own practice" unambiguously confirm Mauritius’ long standing rights in the territorial sea⁵¹⁵ and the exclusive economic zone.⁵¹⁶