Section 7.05.390 - Rules applicable to substance of dispute(1) The arbitral tribunal shall decide the dispute in accordance with such rules of law as are chosen by the parties as applicable to the substance of the dispute. Any designation of the law or legal system of a given state shall be construed, unless otherwise expressed, as directly referring to the substantive law of that state and not to its conflict of laws rules.(2) Failing any designation by the parties, the arbitral tribunal shall apply the law determined by the conflict of laws rules which 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 applicable to the transaction.