This book examines some of the most prominent contemporary theories of compliance with international law. It is argued that these theories ultimately rely on some political philosophy and that therefore their strengths and weaknesses can be traced back to those of the respective philosophical background. The approach finally taken is based on some recent empirical and theoretical research undertaken and as such provides new insights to the major works of the authors that are at the core of the discussion. As such, it aims to contribute fresh input to a contemporary discussion at the heart of the international system.The book combines theoretical arguments with insights gained from a practitioner's point of view. It is of interest particularly for scholars and practitioners of international law and international relations as well as legal and political philosophers.