(1) The arbitral tribunal shall decide the dispute pursuant to the rules of law chosen by the parties to apply to the substance of the dispute. Any designation of the law or legal system of a state or country shall be construed, unless otherwise expressed, as directly referring to the substantive law of that state or country and not to its conflict-of-laws rule.
(2) Failing any designation by the parties, the arbitral tribunal shall apply the law determined by the conflict-of-laws rules that it considers applicable.
(3) The arbitral tribunal shall decide ex aequo et bono or as amiable compositeur, only if the parties have expressly authorized it to do so.
(4) In all cases, the arbitral tribunal shall decide in accordance with the terms of the contract and shall take into account the usages of the trade which apply to the transaction.