Treaties, Custom, Iteration, and Public Choice

Abstract

Assume that, in attempting to effect international legal cooperation, national leaders can choose between using treaties and customary law as the form in which to embody their cooperative efforts. Which form of international law would we expect them to choose? I analyze this question using two different methodological approaches, both of which are "rational-choice" methodologies in the sense that they assume that the relevant decision-makers rationally pursue known goals. The first approach, which I call the "iterative perspective," focuses on minimizing transaction costs. The iterative perspective predicts that national leaders will choose treaties to effect international legal cooperation. The second approach, which I call the "public choice" perspective, focuses on the desire of national leaders to maximize their freedom of action. The public choice perspective predicts that national leaders will choose customary international law to effect international legal cooperation. With these divergent predictions in mind, I then move from theory to evidence. I argue that, at least since World War II, it is treaties rather than customary laws that have been the favored embodiment of international legal cooperation. I conclude that the evidence is thus more consistent with the iterative perspective than with the public choice perspective.