Feasibility of Applying Lex Mercatoria in Arbitration Based on Ex aequo et bono and Amiable Compositeur

Transnational commercial rules (lex mercatoria) as the third legal system along with the domestic and international legal systems, are used to regulate commercial relations. One of the controversial issues related to the transnational commercial rules is if the parties have agreed that their dispute should be resolved ex aequo et bono and or by way of amiable composition, would such agreement imply granting the arbitrator the authority to apply transnational commercial rules? In other words, this article examines if in cases where the arbitrator is empowered to act ex aequo bono or as amiable compositeur, they may, directly or indirectly, apply lex mercatoria or not. This disagreement stems from the fact that ex aequo et bono and amiable compositeur have been considered the core foundation and origin of most transnational commercial rules. Therefore, it is suggested that the application of transnational commercial rules over disputes, is an implicit prescription in proceedings based on ex aequo et bono or by way of amiable composition, and vice versa; That is, if the arbitrator is authorized to decide ex aequo et bono or by way of amiable composition, they can apply lex mercatoria. In this research, an attempt is made to analyze the above proposition in legal thoughts and practical procedures. It should be underlined that ex aequo et bono decision-making and amiable composition, due to the unicity of their foundation with lex mercatoria, would result in more flexibility in the arbitration process. In addition, the article examines what would be the arbitrator's scope of authorities in ex aequo et bono decision-making and amiable composition to set aside strict legal rules.