“Rules of Law” and Lex Mercatoria Determination Under the Auspice of ICC Arbitration

The ICC arbitration, being one of the most common ones in international commercial arbitration, is also one of the most benevolent to the application of supranational substantive rules, including the lex mercatoria. While it has not always been the case, since 1998, the arbitrators may less focus on complex reasoning as to why the lex mercatoria might be applicable, and rather may fully concen-trate on the rightful adjudication of the dispute. This article presents a summary of changes in ICC arbit-ration stance on the applicability of lex mercatoria, as voiced by the permission to inter partes elect, or ex post determine, substantive “rules of law” rather than just a “law”. Connotations of ICC jurispru-dence towards applicable lex mercatoria and its relationship to state law is also discussed and evalu-ated.