49. Rules applicable to substance of dispute
(1) The arbitral tribunal shall decide the dispute in accordance with the rules of law chosen by the parties. Any designation of the law or legal system of a given State or jurisdiction shall be construed, unless otherwise expressed, as directly referring to the substantive law of that State or jurisdiction and not to its conflict of laws rules.
(2) In the absence of any designation by the parties, the arbitral tribunal shall decide the dispute in accordance with the rules of law it considers appropriate.
(3) In either case, the arbitral tribunal shall take trade usages into account.