How International Law Works presents a comprehensive theory of international law by uniquely applying social-science models and ideas to the field. In recent years, appeals to "international law" have become increasingly central in international disputes. Yet despite the enhanced importance of international law, there is no well-developed set of theories on the ways in which international law shapes policy outcomes. Utilizing rational choice theory, Andrew Guzman assumes that states behave rationally and selfishly: At the heart of their compliance with international law is the basic fact that a failure to live up to legal obligations today will impact a country's ability to extract concessions in the future. A violation will also generate a costly loss of "reputation." By highlighting the rationality of states, Guzman explains that a proper understanding of how international law functions can help resolve some--but not all--of the persistent problems that plague relations between nations. Covering a wide range of disputes between countries, How International Works provides a thoroughgoing guide to the complexities of international law.