In this edited collection, Theodor Meron, the world's most important author on issues of international humanitarian law, brings together a fascinating collection of his essays on war crimes and related areas, together with a new concluding chapter, from which the book takes its title, which brings together the themes explored in the essays. The rapid and fundamental developments in the last few years on the establishment of individual criminal responsibility for serious violations of international humanitarian law have been such that now more than ever is an appropriate time to assess their principal features. This book will be welcomed by all scholars in the field as a useful and significant contribution to our understanding of international humanitarian law.