Review Essay

• Simpson, G

Abstract

The rejuvenation of international law in the last decade has its source in two developments. On the one hand, 'critical legal scholarship' has infiltrated the discipline and provided it with a new sensibility and self-consciousness. On the other hand, liberal international lawyers have reached out to International Relations scholarship to recast the ways in which rules and power are approached. Meanwhile, the traditional debates about the source and power of norms have been invigorated by these projects. This review article considers these developments in the light of a recent contribution to international legal theory, Michael Byers' <it>Custom, Power and the Power of Rules</it>. The article begins by entering a number of reservations to Byers' imaginative strategy for reworking customary law and his distinctive approach to the enigma of opinio juris. The discussion then broadens by placing Byers' book in the expanding dialogue between International Relations and International Law. Here, the article locates the mutual antipathy of the two disciplines in two moments of intellectual hubris: Wilson's liberal certainty in 1919 and realism's triumphalism in the immediate post-World War II era. The article then goes on to suggest that, despite a valiant effort, Byers cannot effect a reconciliation between the two disciplines and, in particular, the power of rules and the three theoretical programmes against which he argues: realism, institutionalism and constructivism. Finally, Byers' book is characterized as a series of skirmishes on the legal theory front; a foray into an increasingly rich, adversarial and robust dialogue about the way to approach the study of international law and the goals one might support within the discipline. Here, the article dwells on Byes' doubts about critical legal scholarship and argues that Byers has misunderstood the nature of power and drawn an unsustainable distinction between arguments about rules and rules themselves.