The decisional logic of treaty regime-making

Abstract This Article develops a positive, decision-theoretical model of the logic that states or sub-national polities use in deciding to delegate sovereignty to a multilateral treaty regime. Rather than solving one or more specific regime-design problems, this Article develops a general framework for analyzing regime creation given a variety of cooperation problems and other assumptions. Perhaps most importantly, it introduces a dual-ideal-point framework for analyzing the creation of regimes with the possibility of opt-in. I first show how these regimes can be modeled spatially, and I then develop a formal decision-theoretical model that explains what factors polities consider in drafting, negotiating, and opting into the regimes. Unlike models of generic non-cooperative bargaining in the economics and political science literatures, this model is developed around the several dynamics unique to supranational regimes, especially, voluntary opt-in rules. The model leads to several findings, pertaining to where a regime creates partial externalities (public goods), no externalities (club or private goods), or only externalities (pure public goods). More practically, the model shows how a rational polity should consider the relative distributions of these regime traits to maximize its utility during the regime’s negotiation and creation processes. Given how many traditional constitutional prerogatives have been transferred to international institutions over the past few decades, the model has theoretical and empirical implications for international and constitutional law alike.