This study aims to examine the substantive applicable law in different arbitral tribunals, especially the ICSID and the Iran-US Claims Tribunal. Additionally it examines the role of international law and whether it has supremacy over national laws. To that end, this publication is mainly based on case studies, the most cited ICSID and Iran-US Claims Tribunal cases. Furthermore, it addresses scientific works on this topic with regard to various arbitration rules and in particular to the applicable law.
