This Fourth Edition of Public International Law in a Nutshell is a concise yet accurate summary of the field of public international law, covering its basic sources, actors, and procedures, and key subject matter areas, such as human rights, the law of the sea, international environmental law, the law of war, and U.S. foreign relations law. This edition is fully updated to include recent treaties (e.g., on jurisdictional immunities of states), institutions (e.g., the African Court on Human Rights), and Supreme Court decisions (e.g., Sosa and Hamdan).The book is intended to be helpful for students, scholars, and practitioners alike.