عنوان مقاله [English]
In the course of international tribunals’ adjudications, one of the most important issues to deal with is to solve the problem of conflict of laws through determining the applicable law. Monism and the priority of international law over domestic law was accepted and confirmed by the majority of jurists, especially those believe in monism doctrine, from different legal systems. For the lawyers and arbitrators the interpretation of treaties and contracts is a vital and basic step in litigation or arbitration procedure. Toward determining of rights and duties of parties in investment law, the occurrence of conflict of laws between international law and domestic law is a usual and ordinary subject matter. Notwithstanding the indications of doctrine of priority of domestic law over international law, but the search in the Treaties, Contracts, Doctrine and Legal precedents verify the contrary view point. Today the states liabilities in investment arbitration even with the contractual origination, changed to the states international liabilities, with presence of new provisions like as umbrella clause (As catch all provision), which reaffirm on the priority and influence of international law over domestic law. My uppermost aim in writing this article has been to study and show this evolutionary legal transformation in international investment law and to meet that end legal precedent has been examined.