Modeling Domestic Politics in International Law Scholarship

In this review essay, we use Eric Posner and Alan Sykes\u27 Economic Foundations of International Law as a springboard to highlight key analytical contributions of rational choice models to the field of international law and to suggest avenues for future research. We argue that Economic Foundations is unusually comprehensive and that, as a result, the field can now respond to a major criticism. Critics have long argued that rational choice models are too abstract to make useful predictions about most issues relevant to international lawyers. We show that this critique is no longer jusified, in part through a systematic classifcation of all articles published in the last decade in two of the flagship journals of the fields of international law and international relations, the American Journal of International Law and International Organization, respectively. That said, we also argue that scholars working in this research tradition can make much progress by relaxing the most troubling assumption of existing rational choice models: the unitary state assumption. We show how two types of models widely used in other fields--principal- agent models and domestic distributional conflict models--can be fruitfully applied to international law debates. Our critique is thus internal; we suggest that it is possible to keep the simplicity and clarity typical of game-theoretic models while assuming that key constituencies within the state, rather than the state itself, can rationally pursue interests. Moreover, we also argue that some important policy implications of earlier rational choice models change when we weaken the unitary state assumption. Finally, even though our critique is internal to the law and economics tradition, we also show how studies from more sociologically minded traditions often yield complementary, rather than conflicting, insights