'Ulf Linderfalk's new book Understanding Jus Cogens in International Law and International Legal Discourse is a timely contribution to the debate on the criteria and consequences of jus cogens in international law. A debate which has, for the most part, been characterised by participants speaking past each other. Building on his previous accomplished work on the theory of jus cogens, Linderfalk takes a step back in order to examine the common assumptions underlying dominant approaches to jus cogens in international law. The result is a book that has the potential to open the lines of communication in the pursuit of better understanding of jus cogens.'--Dire Tladi, University of Pretoria, South Africa