Jus Cogens Re-examined: Value Formalism in International Law

Jus cogens is receiving renewed interest both in legal practice and academia. A number of recent books approach the subject from different angles, attributable to different strands of the debate. Some approaches are predominantly technical and cannot adequately address the symbolic value of jus cogens. Others argue that considerable legal effects derive from the value dimension of jus cogens but risk skipping over technical niceties. Reading several works that represent these tendencies together points to an insurmountable tension between value orientation and formalism that is indicative of the current state of jus cogens in international law. In this review essay, I discuss a legal technique approach, a value approach relying on social contract theory and a practice-oriented approach to the study of jus cogens, represented by the three books under review. On the basis of the current state of case law and research, I also identify the most pressing challenges for our understanding of jus cogens and reflect on the relation of scholarship and the parallel work of the International Law Commission and, more generally, on the performative force of theories. I conclude that jus cogens as a manifestation of ‘value formalism’ in international law is an even greater conceptual conundrum than it was 20 years ago. * Dr. iur., Privatdozent, Goethe University, Frankfurt am Main, Germany; Visiting Professor, Humboldt University, Berlin, Germany. Email: t.kleinlein@jur.uni-frankfurt.de. 296 EJIL 28 (2017), 295–315