Professor Ian Brownlie, CBE, OC, FBA, DCL retired from the Chichele Chair of Public International Law at the University of Oxford, a post that he has held since 1980. Before that he taught at Oxford, Nottingham, and the London School of Economics. He is widely recognized as one of the leading international lawyers of our time, and as well known and appreciated as much for his seminal publications and teaching over the years, as for his work as a practitioner. To express their gratitude for his supervision and support, a number of his present and former students from Oxford and London (many now prominent in academic life, foreign affairs, and practice), have written this collection of essays in honour of their former teacher. The collection is a very personal one reflecting the close and warm relationship between teacher and students and results in a wide-ranging overview of the subjects supervised by Professor Brownlie during more than forty years as an academic teacher. The collection takes its title, The Reality of International Law, from an appreciation of Professor Brownlie's personal contribution to the development of the subject. His commitment to international law as a system for the regulation of affairs between states has long been characterized by a strong sense of ideals, political and human, but also by an awareness, duly transmitted to his students, and of what law is in practice, of what is achievable, and of what remains to be done.