(Cambridge University Press) In this book, Lepard seeks to articulate a comprehensive theory of customary international law that addresses some of the various conceptual and practical enigmas found within the field. Using a multidisciplinary approach, Lepard draws insights from various fields including legal theory, philosophy, political science, and game theory. Additionally, Lepard is anchored in an ethical framework that allows him to explore the relationship between ethics and customary international law. Lepard is the Law Alumni Professor of Law at the University of Nebraska College of Law.