Written by one of the world's leading international lawyers, this is a landmark publication in the teaching of international law. International law can be defined as 'the rules governing the legal relationship between nations and states'. However, with political, diplomatic and socio-economic factors shaping the law and its application, international law is much more complex. This refreshingly clear, concise textbook encourages students to view international law as a dynamic system of organising the world. Bringing international law back to its first principles and breathing new life and energy into the subject, the book is organised around four questions: Where does it come from? To whom does it apply? How does it resolve conflict? What does it say? This fourth edition includes references to new case-law and literature, and features (brief) discussions on recent topics of general interest, including the Ukraine invasion, global health law and energy law.

Part I. The Structure of International Law: 1. The setting of international law; 2. The making of international law; 3. The law of treaties; 4. The subjects of international law; 5. Jurisdiction, powers, and immunities; 6. The individual in international law, including human rights; 7. The law of responsibility; 8. International courts and tribunals; 9. Sanctions, countermeasures, and collective security; Part II. The Substance of International Law: 10. Use of force; 11. The law of armed conflict; 12. International criminal law; 13. The seas, the air, and outer space; 14. Protecting the environment; 15. The global economy; Part III. The Surroundings of International Law; 16. Domestic courts and their relationship with international law; 17. The politics and ethics of international law and global governance; 18. By way of conclusion.