This chapter provides an understanding of where international law is at (including customary international law, treaty and case law) in terms of its achievements and shortcomings regarding cooperation over environmental protection and use of transboundary freshwater ecosystems. This work provides a basis for critical analysis over the proceeding book chapters, in relation to the value added by the UNECE. The chapter lays the foundations for determining the UNECE regime’s relationship to international water law, international environmental law and general international law. It explores the role of international courts and the international law commission in interpreting outdated water treaties and bringing their standards of environmental protection closer to contemporary scientific understandings and the more progressive multilateral environmental agreements in accordance with the principle of systemic integration. It also explores instances where Courts have arguably has not gone far enough, leaving gaps in understanding. Unlike Courts, pan-regional or basin treaties and their river basin commissions can develop and interpret rules and principles of international water law on a continual and comprehensive basis and provide the institutional framework which supports implementation and compliance with international water law. This hypothesis, on the added value of the UNECE water regime, is tested over the proceeding chapters.