• Beatriz Calado de Sousa University of Lisbon, School of Law
Keywords: International law, Jus cogens, Peremptory norms of general international law, Vienna Convention on the Law of Treaties


This paper aims to delve into the qualities and content of norms of general international law classified as peremptory (jus cogens). To do so, three questions will be answered: (i) how does jus cogens arise, (ii) how is jus cogens changed and eliminated and (iii) what is jus cogens “utility”? The first question will be answered by adopting a two-stage formal criterion, based on the provisions of the Vienna Convention on the Law of Treaties. In this section, it will be demonstrated that jus cogens may have trivial content. Next, it will be argued that the process of modification and elimination of jus cogens depends to a great extent on the non-verification of the necessary conditions for its emergence. Finally, the “utility question” will deal with the alleged constitutionalist function of jus co- gens and its relevance, namely by limiting the power of the States and strengthening the rule of law.


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