It has never been more important to understand how international law enables and constrains international politics. By drawing together the legal theory of Lon Fuller and the insights of constructivist international relations scholars, this book articulates a pragmatic view of how international obligation is created and maintained. First, legal norms can only arise in the context of social norms based on shared understandings. Second, internal features of law, or criteria of legality', are crucial to law's ability to promote adherence, to inspire fidelity'. Third, legal norms are built,...