The emergence of jus cogens in the Vienna Convention on the Law of Treaties

The aim of this paper is to outline the emergence of jus cogens in the Vienna Convention on the Law of Treaties by analyzing its preparatory works for the Convention and the evolution of the concept itself. The analysis of the foundations of jus cogens norms, both expressed by jurists engaged in the theory and practice of international law before the Vienna Convention was concluded and by the authors of that treaty, is crucial to the proper description and application of the concept of jus cogens in the contemporary international law.