The deliberations of the Tribunal take place in private, usually after a hearing or procedural session when the members of the Tribunal are all gathered for an in-person meeting. Deliberations can also held by telephone or videoconference or by correspondence (Article 23 of the Arbitration (Additional Facility) Rules).
Agreements concerning the presence and quorum and the manner in which the Tribunal decides are usually reached at the occasion of the first session of the Tribunal. A majority of the Tribunal must be present at deliberations, and the parties may agree that all members must be present (Article 22(2) of the Arbitration (Additional Facility) Rules).
If the Tribunal deliberates by correspondence, all members must be consulted. The parties may agree that the President of the Tribunal decide without consulting the other members in urgent situations, subject to possible reconsideration of the decision by the full Tribunal. Such decisions typically relate to the extension of time limits and other urgent procedural questions (Article 33 of the Arbitration (Additional Facility) Rules).
To ensure a time effective process, the ICSID Secretariat encourages Tribunals to reserve time for deliberations immediately after hearings. The ICSID Secretary of the Tribunal is available to assist Tribunals during these meetings.