Wikipedia
Ex aequo et bono ( Latin for "according to the right and good" or "from equity and conscience") is a Latin phrase that is used as a legal term of art. In the context of arbitration, it refers to the power of arbitrators to dispense with consideration of the law but consider solely what they consider to be fair and equitable in the case at hand.
Article 38(2) of the Statute of the International Court of Justice (ICJ) provides that the court may decide cases ex aequo et bono only if the parties agree. In 1984, the ICJ decided a case using "equitable criteria" in creating a boundary in the Gulf of Maine for Canada and the US.
Article 33 of the United Nations Commission on International Trade Law's Arbitration Rules (1976) provides that the arbitrators shall consider only the applicable law unless the arbitral agreement allows the arbitrators to consider ex aequo et bono, or amiable compositeur, instead. This rule is also expressed in many national and subnational arbitration laws such as section 22 of the Commercial Arbitration Act 1984 (NSW).
On the other hand, the constituent treaty of the Eritrea–Ethiopia Claims Commission explicitly forbids the body from interpreting ex aequo et bono.