(1) The Tribunal shall apply the rules of law designated by the parties as applicable to the substance of the dispute. Failing such designation by the parties, the Tribunal shall apply:
a)
the law which it determines to be applicable; and
b)
the rules of international law it considers applicable.
(2) The Tribunal may decide ex aequo et bono if the parties have expressly authorized it to do so and if the law applicable to the arbitration so permits.