This chapter concludes this book by exploring the success, limitations and future global outlook of the pan-European UNECE environmental regime including challenges for future non-UNECE accession, drawing upon an unparalleled seventy years of experience supporting international law on transboundary watercourses and freshwater ecosystems. From the key findings, this book draws a series of overarching and cross-cutting insights into the rising impact and contribution of the UNECE regime to the clarification and development of international law, which also raises outstanding areas for future research. It explores questions of legitimacy as the UNECE regime moves towards its new global role. This research bears in mind the importance of distinguishing policy arguments for signing up to the UNECE regime with legal arguments. The problem arising from a legal perspective is to ask whether it is good legally when international courts or international institutions endorse a regionally specific detailed regime as global law? This analysis demonstrates that the UNECE environmental instruments were never intended to be geographically exclusive and have also already been co-developed by non-UNECE countries for some time. This research supports the UNECE’s endeavour to embrace a global role but cautions that a strong mandate from non-UNECE countries must drive this process.

The latest Sustainable Development Goal (SDG) reporting exercise demonstrated the wide spectrum of arrangements and shortcomings for transboundary cooperation at the river basin level in the UNECE regime, from basins with comprehensive legal frameworks to basins with no agreement at all. Transboundary water cooperation works best when there is a basin-level agreement and these agreements should be more detailed than regional or global treaties but must incorporate these rules and principles. This chapter identifies how the UNECE water regime contributes to transboundary water cooperation at the basin level through the development of basin agreements, river basin organisations and less formal cooperative arrangements. It identifies how the UNECE has supported implementation and compliance with the UNECE regime and international law at basin and national level and the involvement of non-state actors. It examines a range of basin arrangements including those with no agreement, like the Western Bug, or basins with advanced frameworks like the Danube and Sava. It also analyses the value of the UNECE regime in basins already subject to EU environmental law – seeking to understand the specific contribution of the UNECE vis-à-vis the EU law and discusses why EU states have demonstrated interest in the UNECE regime.

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.