國際慣習法 形成의 게임이론 模型

International law lecturers are confronted with foundational questions from the very start of the course. How does international law, especially customary international law, affect state behavior in the absence of a centralized enforcer? Why states participate in making international law if they are not sure whether it will really regulate their relations? Game theory shows that norms can be formed and maintained without centralized authority if states are put in a multilateral prisoner's dilemma situation and such a situation is repeated indefinitely. There are two basic assumptions in this analysis: First, states prefer the benefits of long-term compliance to those of short-term violation. Second, states involved, at least injured state, retaliate to violation by others. This article reviews game theory of customary international law. Jack Goldsmith and Eric Posner, pioneers in this field, have argued that iterated multilateral prisoner's dilemma game is unlikely to allow customary international law to affect state behavior. George Norman and Joel P. Trachtman, however, point out that this assertion is incorrect in theory. Although game theory cannot capture all real world details, game theoretic model seems to be useful in that it shows the plausibility of the formation and maintenance of customary international law in the absence of centralized authority.