Ius Cogens: A puzzle

Abstract

The notion of 'ius cogens' is one of the most controversial in international law. Evidence of the concept traces back at least to the first half of the twentieth century. The Vienna Convention on the Law of Treaties (VCLT) codified it, specifically in Article 53. Since then, 'ius cogens' has been a focal point for scholarly debates, institutional works and judicial decisions. Given the considerable amount of writing on the matter, little room is left for approaching the topic in an original way. The subject is theoretically complex and entails significant practical consequences. The awkward relationship between theory and practice makes it difficult to discuss 'ius cogens' coherently. The present paper provides a literal analysis of the main positive norms regulating 'ius cogens' and aims to define a consistent interpretative pattern. It focuses on the structure of 'ius cogens' and its implications. For the purposes of this paper, the word 'norm' (rule) is basically intended as a synonym of 'duty' and 'obligation'. The analysis deals mainly with states. It takes into account, on the one hand, the VCLT, and, on tbe other hand, the Project on State Responsibility (PSR). Some final remarks concern individuals, especially in the light of the Rome Statute of the International Criminal Court (ICC). the matter is considered at the level of primary and secondary norms. According to Kelsen, 'primary norms' are those prohibiting specific behaviour, such as the duty enjoining a state from attacking another state, whereas 'secondary norms' set up sanctions for the violation of primary norms, such as the duty to provide reparation in a case of aggression.