The Role of Supplementary Means (Article 32 VCLT) in Treaty Interpretation by International Courts and Tribunals

In the contemporary landscape of international law, the proliferation of treaties underscores the importance of their interpretation and implementation. The Vienna Convention on the Law of Treaties (VCLT) provides a framework for this, particularly through Articles 31–33. While Articles 31 and 32 offer methods for interpretation, they also pose challenges due to their ambiguous formulation. Despite this, international judicial bodies, such as the International Court of Justice (ICJ) and the World Trade Organization (WTO), increasingly rely on these principles, notably seen in cases like Oil Platforms and the OSPAR award. This thesis examines the utilization of supplementary rules of interpretation, as outlined in Article 32 of the Vienna Convention on the Law of Treaties (VCLT), by international courts and tribunals. In Chapter One, the study delves into the general rule of interpretation (Article 31) and the interpretation of multilingual treaties (Article 33) of the VCLT. Building upon this foundation, Chapter Two focuses on the exploration of Article 32 and its practical application. Through a detailed analysis of case studies involving international judicial bodies such as the International Court of Justice (ICJ), the World Trade Organization's Appellate Body, and investment treaty tribunals, the research illuminates how these supplementary rules are leveraged in diverse scenarios. By shedding light on the dynamic interplay between treaty interpretation and evolving international norms, this study contributes to a deeper understanding of the complexities inherent in international law. Moreover, it provides insights into the strategies employed by international courts and tribunals to navigate these complexities, ultimately advancing the cause of the rule of law and international justice.