An Introduction to the VCLT and Its Role in ISDS: Looking Back, Looking Forward

This chapter introduces the present book, The Vienna Convention on the Law of Treaties in Investor-State Disputes: History, Evolution, and Future. The publication of this book celebrates two important VCLT-related milestones: the fiftieth anniversary of its opening for signature (in 2019) and the fortieth anniversary of its entry into force (in 2020). In the intervening decades, the VCLT – as the ‘treaty on treaties’ – has achieved a rich and nuanced track record of use in international law. This introduction, and the chapters that follow, focus on the VCLT’s influence in investor-State disputes. The significant number of investor-State arbitration decisions and awards, a considerable proportion of which directly engage with the VCLT, makes this a key field of study for understanding the VCLT’s contents and impact so that future opportunities for its continued relevance and use can be identified. To open the book and contextualize the chapters that follow, this chapter provides a historical account that examines the VCLT’s development, including by detailing the ILC’s winding road and iterative process towards the development of the VCLT. It then introduces the contours of the VCLT, explaining its scope and focus, and highlighting its key provisions. It next focuses on the impact of the VCLT beyond its application as a matter of treaty law, noting the extent to which provisions of the VCLT are accepted to reflect customary international law. Finally, it draws out the links between the VCLT, international investment law generally, and investor-State dispute settlement (ISDS) specifically. This final section also introduces the organization and structure of this book, highlighting the book’s presentation of perspectives that illuminate the value of looking back on the VCLT and its rich track record, in order to look forward and unlock the utility of the VCLT for grappling with emerging systemic challenges in ISDS and international investment law more broadly.