This book has its origins in work we presented at a conference on Freedom From Contract, organized by Omri Ben-Shahar of the University of Michigan and hosted by the University of Wisconsin Law School. That conference reinforced two impressions that had motivated our collaboration: Contracts scholars and international lawyers have not made much of an investment in learning what each field has to offer the other, and the possibilities for mutual enrichment are great. This extension of that project represents our effort to demonstrate both that problems in international relations illuminate some of the most challenging issues in contract theory today, and that international law takes on great theoretical richness and rigor when it employs the insights of contract theory.

For the most part, our theoretical claims in this book are positive and descriptive rather than normative. We believe that contract theory (an umbrella phrase that we use to describe both the law and economics of contracts as well as the separate discipline of the economics of contract) explains much of current practice regarding the enforcement of international law. Seeking to understand why we see the legal institutions we do, as opposed to describing and defending a better world in which we might live, is more familiar to contracts scholars than to international lawyers. One of the exciting challenges of international law and international relations theory, however, is to give a convincing account of the world as we find it, and for this purpose contract theory does important work.