Gore Kiran N. picture


Mr. Gore Kiran N.

Professorial Lecturer in Law - The George Washington University Law School

Müller Daniel picture


Mr. Müller Daniel

Member of the Paris Bar

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I. Definition


Joinder aims to enhance procedural efficiency by ensuring that all necessary parties to a dispute are present in the same proceeding. As such, it seeks to alleviate the time, costs, and other inefficiencies of multiple and/or parallel proceedings,4 among which may be the risk of inconsistent awards.5 While this tool is commonly used in international commercial arbitration, and it is useful to compare and contrast its use in the commercial context, it is still quite rarely applied in the investment arbitration context.6

II. Distinction between joinder and other ISDS procedural tools


Although a multi-party proceeding can be the result of an ex post joinder or consolidation,7 each of these procedural tools is distinct. Multi-party proceedings (Mass Claims) involve several claimants and/or respondents with separate but related claims, which are presented to an arbitral tribunal collectively from the beginning of the proceedings and do not require additional consent, beyond that originally given to resolve disputes under the treaty through arbitration.8 


On the other hand, consolidation refers to the combination of multiple arbitral proceedings that were originally initiated separately.9

III. Consent as a prerequisite


Any request for joinder must be substantially supported by evidence of the original parties’ consent to such treatment.10 Consent can be manifested in different ways. The parties might have specifically set the rules for joinder in the arbitration agreement, through their choice of substantive law or procedural rules, during the dispute, or even through behavior subsequent to the conclusion of their arbitration agreement.11 The third party should also manifest its consent to join the case12 and should not already be involved in parallel proceedings concerning the same dispute.13

A. Joinder in the ICSID system


There is no mechanism for joinder of third parties in the ICSID system.14 However, similar to the analysis applied to determine whether consolidation of proceedings may be appropriate, Article 44 of the ICSID Convention may be relied upon to join third parties to the arbitral proceeding, assuming the requisite consent exists as this rule does not give “unlimited discretionary powers” to the arbitral tribunal.15 Thus, its application is restrictive and does not give the arbitral tribunal the power to extend its jurisdiction ratione personae in favor of a joinder request in the absence of the requisite consent of all parties concerned.16

B. Joinder under the UNCITRAL rules


The 1976 UNCITRAL Rules do not contain a specific provision on joinder. Although Article 20 provides for the possibility of parties to amend their statement of claim or defense within the limits of the arbitration agreement, an arbitral tribunal has previously refused to grant joinder on this basis.17


The 2010 UNCITRAL Rules include an explicit provision allowing for joinder of “one or more third persons” provided that “the arbitral tribunal finds, after giving all parties including the person or persons to be joined the opportunity to be heard, that joinder should not be permitted because of prejudice to any of those parties.18 In the presence of this provision, an arbitral tribunal limited the scope of application of Article 22 (formerly Article 20 under the 1976 UNCITRAL Rules).19 Further, the arbitral tribunal has discretion to render a single award or several awards covering the parties involved in the arbitration. 

C. Joinder under ICC arbitration rules

D. Joinder under SCC arbitration rules


Article 13 of the SCC Arbitration Rules (2017) provides for the possibility to join third parties to an arbitral proceeding. The request should be made before the constitution of the arbitral tribunal unless the SCC Board decides otherwise.25 The rule explicitly provides for parties’ consultation only in the presence of multiple arbitration agreements.26 The only other requirements are that the third party should be bound by the arbitration agreement and the SCC should not manifestly lack jurisdiction.27

IV. Consequences

A. Cases when joinder was requested and granted


If joinder is granted, in order to avoid annulment of an award under the Dutco principle,28 some believe the third party joining the case after the formation of the arbitral tribunal can be considered as having waived its right to an equal participation to the appointment of arbitrators.29 The 2021 ICC Arbitration Rules introduce the possibility of a third party to join arbitral proceedings after a tribunal has been constituted only if it accepts the existing composition of the tribunal and the existing terms of reference, as this would remedy any contrary claim in the future, including at the annulment stage.30 

B. Cases when joinder was not requested


A party that had not exercised its right to join an existing arbitral proceeding does not relinquish its right to bring separate proceedings. Where a respondent asserted that a claim should be precluded because the claimant had the opportunity to present its claims by joining a previous proceeding, the arbitral tribunal rejected this argument.32 

V. Pragmatic tools used in lieu of formal joinder


Where the applicable arbitral rules and investment treaties do not provide any mechanism for joinder, efficiency, or avoidance of inconsistency between proceedings, parties and arbitral tribunals may pursue pragmatic approaches to achieve these same goals.33 For example, parties may wish to appoint the same arbitrators to hear similar or related cases in parallel and related proceedings.34 Such approach can be observed in claims brought under different arbitration rules,35 or different investment treaties.36


On the other hand, a party wishing to avoid joinder may simply influence the timing of the proceedings so that they are not compatible, as use of the joinder procedural tool presumes that the proceedings to be joined are at similar and comparable stages, whereby joining is practically and logically feasible.38


Choi, D., Joinder in International Commercial Arbitration, in Arbitration International, Volume 35, March 2019.

Hansen, R.F., Parallel Proceedings in Investor-State Treaty Arbitration: Responses for Treaty-Drafters, Arbitrators and Parties, The Modern Law Review 73, No. 4, 2010.

Kauffmann-Kohler, G., Boisson de Chazournes, L., Bonnin, V. and Mbengue, M.M., Consolidation of Proceedings in Investment Arbitration: How can Multiple Proceedings Arising from the Same or Related Situations be Handled Efficiently?, in ICSID Review – Foreign Investment Law Journal, No. 1, 2006.

Kinnear, M. and Mavromati, C., Chapter 15: Consolidation of Cases at ICSID, in Kaplan, N. and Moser, M.J. (eds.), Jurisdiction, Admissibility and Choice of Law in International Arbitration: Liber Amicorum Michael Pryles, Kluwer Law International, 2018.

Menon, S. and Tian, C., Joinder and Consolidation Provisions under 2021 ICC Arbitration Rules: Enhancing Efficiency and Flexibility for Resolving Complex Disputes, Kluwer Arbitration Blog, January 2021.

Moollan, S. and Laborde, G., Parallel Proceedings in Investment Arbitration: Causes, Problems and Possible Solutions, in Banerji, G. and Nair, P. et al. (eds.), International Arbitration and the Rule of Law: Essays in Honour of Fali Nariman, Permanent Court of Arbitration, 2021.

Sabahi, B. and Rubins, N., Chapter VII - Special Procedures: Applications and Motions, in Sabahi, B., Rubins, N. and Wallace, D. (eds.), Investor-State Arbitration, 2nd ed., Oxford University Press, 2019.

Schreuer, C.H., The ICSID Convention - A Commentary, Cambridge University Press, 2001.

Wehland, H., The Coordination of Multiple Proceedings in Investment Treaty Arbitration, Oxford University Press, 2013.

Yannaca-Small, K., Part III Procedural Issues, Chapter 25 - Parallel Proceedings, Muchlinski, P., Ortino, F. and Schreuer, C.H. (eds.), The Oxford Handbook of International Investment Law, Oxford University Press, 2008.

Yannaca-Small, K., Consolidation of Claims: A Promising Avenue for Investment Arbitration?, in International Investment Perspectives, OECD, September 2006.

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