In investor-State arbitration, the tribunal’s chair (or the “president” or “presiding arbitrator”) refers to the presiding arbitrator. In addition to the adjudication function performed by all co-arbitrators, the chair usually also manages the case process, e.g. organising procedural conferences, presiding over the tribunal’s discussion, drafting the orders, decisions and award, etc.

A three-person tribunal is more common in investment arbitration.¹ Subject to the provisions in the applicable investment treaty and the arbitration rules, the main methods of appointing the tribunal’s chair include:

1. the parties’ agreement;²
2. the co-arbitrators;³ or
3. the appointing authority,⁴ including the “ballot procedure” employed by ICSID.⁵

Various institutions and officials may serve as an appointing authority, including the Chairman of the Administrative Council of ICSID, the ICSID Secretary-General,⁶ the Secretary-General of the Permanent Court of Arbitration,⁷ the President of the Court of International Arbitration of the International Chamber of Commerce,⁸ and the President of the International Court of Justice.⁹

The methods above are not exhaustive. It is common to see a hybrid method of appointing the president of the tribunal. The appointing authority may¹⁰ or may not be required to consult the parties before appointing the president.¹¹

Following the general criteria applied to co-arbitrators, the presiding arbitrator is often required to be impartial and independent under most arbitration rules.¹² Recent investment treaties have specified the qualifications of the chair, e.g. nationality other than the disputing parties, expertise and/or experience in public international law, international investment law, settlement of international disputes, etc.¹³ In practice, the disputing parties may, however, waive the nationality and other requirements by agreement¹⁴ and tailor the qualities that they believe the chair should possess.

In waiving the requirements, the parties must be conscious of the mandatory provisions of the applicable treaties. In Urbaser SA & Anor v. Argentine Republic, for instance, the parties originally agreed to waive the nationality requirement of the tribunal members.¹⁵ The waiver was insufficient, however, to circumvent Article 39 of the ICSID Convention, which requires the majority of the tribunal members to have a nationality different than the nationality of the parties to the dispute. The nationality requirement of Article 39 does not apply only if “each individual member of the Tribunal has been appointed by agreement of the parties.” In the absence of the parties’ agreement on each member of the tribunal, ICSID refused to accept the designation of the arbitrators having a nationality of the parties.¹⁶

It is important for a tribunal’s chair in investment arbitration to ensure a fair and efficient arbitration process. See further Arbitrator’s Duties.

As such, in line with the applicable arbitration rules, the applicable treaty and the parties’ agreement, the power and function of the tribunal’s chair may include:

1. presiding over the tribunal’s deliberations and discussions;¹⁷
2. seeking the parties’ views on various matters;¹⁸
3. directing the proceedings, such as control the examination process of the witness and experts during the hearing;¹⁹
4. regulating the order of hearings;²⁰ and
5. making decisions regarding procedural issues under the delegation of power of the other co-arbitrators, such as setting and extending the time limits for proceedings.²¹

In principle, the tribunal may sit in the absence of the president, subject to the provisions on the quorum.²² In the event of a temporary incapacity of the president, other members of the tribunal may perform the president’s functions in accordance with the relevant procedure.²³

The parties are generally advised to avoid a sitting of the tribunal in the absence of the president. Under the ICSID Convention and the Rules, the decisions of the tribunal must be made by an absolute majority of its members.²⁴ A possibility remains, as some commentators have suggested, that a decision may be reached in the absence of the president, as such president may be considered in “abstention” and thus be counted as a negative vote.²⁵