The number of arbitrations on the plane of public international law has greatly expanded in recent years as a result of the widespread use of bilateral investment treaties (“BITs”) under which each Contracting State agrees in advance that the nationals of the other Contracting State will have a right of recourse to international arbitration against it. The method of arbitration agreed may be arbitration under the auspices of the International Center for Settlement of Investment Disputes (“ICSID”) or it may be ad hoc arbitration, or (as in the present case) either method.