A Contrario Reasoning in International Jurisprudence: A Study of Its Function and Nature

A contrario reasoning has been widely used in the Permanent Court of International Justice & its successor (International Court of Justice) on various occasions. The questions ariseing are, what is the criterion for the existence and non-existence of a contrario in the statutory law and legal propositions? To what extent and how has a contrario reasoning been used in the PCIJ and ICJ jurisprudence? What is the importance of this essential argument? And finally, have they contributed to the creation of a predictable legal framework and the coherent development of international law? Analysis of the judgments and advisory opinions regarding this concept help us to understand the nature of the concept and to assess its scope in a better way. Having Followed up the judicial procedure, it is concluded that a contrario reasoning is one of the basic and flexible methods of reasoning in international law. The ICJ and its predecessor have used this form of reasoning to justify their decisions, in the process of interpreting a treaty to discover the spirit of the law, and as a supplementary means for the determination of the content of rules to be applied in certain cases. This form of legal reasoning has also been cited many times and in various contexts in all major substantive fields of international law.