In Philosophy and International Law, David Lefkowitz examines core questions of legal and political philosophy through critical reflection on contemporary international law. Is international law really law? The answer depends on what makes law. Does the existence of law depend on coercive enforcement? Or institutions such as courts? Or fidelity to the requirements of the rule of law? Or conformity to moral standards? Answers to these questions are essential for determining the truth or falsity of international legal skepticism, and understanding why it matters. Is international law morally defensible? This book makes a start to answering that question by engaging with recent debates on the nature and grounds of human rights, the moral justifiability of the law of war, the concept of a crime against humanity, the moral basis of universal jurisdiction, the propriety of international law governing secession, and the justice of international trade law.