This is the eighth edition of Sir Ian Brownlie's classic distillation of public international law. Serving as a single volume introduction to the field as a whole, the book seeks to present international law as a system that is based on, and helps structure, relations among states and other entities at the international level. It aims to identify the constituent elements of that system in a clear and accessible fashion. This eighth edition, fully updated by James Crawford, Whewell Professor of International Law at the University of Cambridge, continues to provide the balance, clarity and expertise expected from this classic text. Completely updated to take account of the many areas of expansion and development in international law which have occurred since earlier editions, all chapters have been reviewed and brought up to date. The eighth edition features a new introduction and the chapters on environmental law, immunities, responsibility, use of force and high seas freedoms have been substantially rewritten. It remains an important textbook for students, undergraduate and graduate, treating core issues from a lawyer's perspective. It is also a vade mecum for practitioners desiring a solid footing on which to make further enquiries.