This publication is the result of a symposium held in 2004 at the Kiel Walther Schücking Institute for International Law on the occasion of its 90th anniversary. In 2000 the International Law Commission of the United Nations in its preliminary study on dangers associated with conflicts between various normative subsystems of international law stated that the fragmentation of international law could endanger the stability as well as the consistency of international law and its comprehensive nature.It is against this background that this volume contains an in-depth analysis as to whether divergent trends have emerged, and if so to what extent, with regard to the sources of international law, its subjects, questions of State responsibility and dispute settlement with regard to the law of the sea, international humanitarian and international criminal law, human rights, international environmental law and international economic law. Besides, the book also addresses the question whether, and if so which, rules have developed to cope with conflicts between the various subsystems just mentioned. It therefore constitutes an essential contribution to the ongoing and crucial debate on the fragmentation of modern public international law.