International law ascribes to the conferral of a jus cogens status on a norm a particular legal significance. Bluntly put, jus cogens norms have legal consequences that norms of ordinary international law do not. International lawyers have a great many different ideas of what these legal consequences are more precisely. As of yet, the reason for this divide has not been fully clarified. This void tends to confuse jus cogens discourse on several issues such as the immunity of states and state officials in judicial proceedings originating in the violation of jus cogens norms, or the extradition of alleged perpetrators of international crimes, or again the non-applicability of amnesty law concerning such crimes. It also impedes the justification of judicial and other legal decisions.

As this article argues, contrary to the general assumption, a lawyer’s conception of the legal consequences of jus cogens is not value-neutral but dependent on his or her preferred understanding of the concept of law. The argument goes briefly as follows: (1) What causes international lawyers to disagree is the issue of whether or not jus cogens norms entail obligations concerned with their own enforcement. (2) This is essentially an issue concerning the individuation of norms. (3) Depending on whether a lawyer takes the position of a legal positivist or a legal idealist, he or she uses different criteria for the individuation of jus cogens norms. (4) And this is why, for legal idealists, jus cogens norms entail obligations concerned with their own enforcement, whereas for legal positivists they do not.

Ulf Linderfalk is Professor of International Law in the Faculty of Law, Lund University, which he joined in 2001. He is a general international lawyer, who takes a special interest in questions relating to international legal structure. His research has examined issues arising from phenomena such as normative conflict, legal hierarchy, treaty interpretation, the identity of special regimes, cross-fertilisation among such regimes, legal principles, legal discretion, balancing, and conceptual terms. He is the author of four monographs – including the recent ‘Understanding Jus Cogens in International Law and International Legal Discourse’ (Edward Elgar, 2020) – two textbooks (both of which are available in updated second editions); four co-edited volumes; and a total of some 30-40 articles in high-ranking peer-reviewed international law journals. 


The PIL Discussion Group hosts a weekly speaker event and light lunch and is a key focal point for PIL@Oxford. Topics involve contemporary and challenging issues in international law. Speakers include distinguished international law practitioners, academics, and legal advisers from around the world.
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Convenors of the Oxford Public International Law Discussion Group are: Eirini Fasia and Hannes Jöbstl.

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