Seeking for a Criterion to Define Legitimacy in International Legal System

Legitimacy is a vague and complicated concept in international legal system; Because of the complexity of the concept there will be a requirement to find out that how legitimacy in international law should be evaluated. Legitimacy needs a fixed framework to be evaluated in the context of the international law in order to help the system to be stable. Hence, to answer the question that what is the appropriate criterion to determine legitimacy, three paradigms have been designed. At the first, legitimacy is considered as acceptability among the peoples and also among Rule - making Institutions. As it is not completely compatible with the current international law and creates some difficulties in this context, thus, creation of a paradigm that is based on the international law values and also result – orientated will be the last resort. Accordingly, the hypothesis of this article is that legitimacy means compatibility with the values of the international society.