In recent decades, there has been a considerable growth in the activities of international tribunals and the establishment of new tribunals. Furthermore, supervisory bodies established to control compliance with treaty obligations have adopted decisions in an increasing number of specific cases. National courts further add to the practice of adjudication of claims based on international law. While this increasing practice of courts and supervisory bodies strengthens the adjudicatory process in international law, this development also poses challenges to the unity of international law. Most of these courts operate within their own special regime (functional, regional, or national) and will primarily interpret and apply international law within the framework of that particular regime. The role of domestic courts poses special challenges, as the powers of such courts to give effect to international law, as well their actual practice in applying such law, will be colored by national law. Against the background of differing normative appraisals of the phenomenon of fragmentation, this book enhances the understanding of how international and national courts can, and do, contribute to or mitigate problems associated with fragmentation. It contains case studies from international regimes - including the World Trade Organization, the International Monetary Fund, investment arbitration, and the European Court of Human Rights - and from various national jurisdictions - including Japan, Norway, Switzerland, and the UK - providing an improved basis for conclusions to be drawn in the final chapter. In particular, this conclusion examines the principles and techniques that international and national courts have applied to counteract the negative effects of fragmentation. (Series: Studies in International Law - Vol. 40)