This new edition of a textbook first published in 2000 provides a comprehensive account of the law of treaties from the viewpoint of two experienced practitioners. It draws on the combined experience of Anthony Aust, the original author, and Jeremy Hill, until recently Legal Counsellor in the Foreign, Commonwealth and Development Office, London. The book provides a wealth of examples of the problems experienced with treaties on a daily basis. The authors explore numerous precedents from treaties and other related documents, such as non-legally binding instruments. Using clear and accessible language, the authors cover the full extent of treaty law, with both practitioners and students in mind. Modern Treaty Law and Practice is essential reading for officials in governments and international organisations, lawyers practising in international law, and teachers and students of law, political science, international relations and diplomacy who have an interest in treaties.