This study aims to examine the substantial status of the Vienna rules of treaty interpretation (Articles 31 and 32 of the Vienna Convention on the Law of Treaties) as a norm of international law and reflect upon the value and role of preparatory work, or travaux preparatoires, within the said Vienna rules.
It begins with inquiry into the genesis of rules of treaty interpretation from the era of classicism up to the early modern academic discourse of Europe, followed by an overview of different theoretical approaches advocated by Western academics in the early 20th century. The jurisprudence of the Permanent Court of International Law (PCIJ) and certain early decisions of the International Court of Justice (ICJ) are also analyzed in order to understand the status of rules of treaty interpretation in international law prior to the International Law Commission (ILC)’s intervention. The ILC proposed systematic rules of treaty interpretation building on the mainstream academic views as well as the approaches taken by the International Courts. The ILC-drafted rules were finally adopted by the Vienna Conference on the Law of Treaties (1968-1969). It is understood that the Vienna rules are the product of compromise and fusion of existing schools of thought, that is textualism, intentionalism, and teleological view. The ICJ began to accept the Vienna rules in its jurisprudence two decades after adoption of the Vienna Convention: Articles 31 and 32 were gradually recognized by the Court to be the authoritative guide to treaty interpretation in the 1990s, culminating in recognition of Article 31 as reflection of customary international law in 1994, followed by the declaration several years later that Article 32 was also reflective of customary international law. The customary status of the Vienna rules have been repeatedly confirmed by the ICJ’s subsequent judgments and opinions with cumulative reference to its own precedents, starting from the 1994 decision.
Looking back on the trajectory of how the Vienna rules emerged and gained its current status, certain narrative could be identified: that is, customary rules of treaty interpretation have been formed through seamlessly continuous, linear development of law from the jurisprudence of the PCIJ to early decisions of the ICJ, integrated by the work of the ILC, leading to final confirmation and recognition by modern practice of the ICJ. A closer examination of each linkage, however, reveals inconsistency, discontinuity or gaps between what was declared to be and what really was: the internal inconsistency of the jurisprudence of the PCIJ; incorrect reference to the PCIJ cases by the early ICJ decisions; lack of any argument or evidence in the identification of customary international law in the ICJ cases, to name a few. In particular, the rise of the Vienna rules to the level of the rules of customary international law could be seen as a typical example of how the ICJ resorted to the technique of assertion, rather than induction or deduction, to identify customary international law in existing treaties, in an inevitable normative attempt to perform its essential judicial functions. There still remains uncertainty as to the basis of assertion of customary character of the Vienna rules as well as its inevitability. In this context, a fundamental question is raised of the genuine status of the Vienna rules: are they obligatory legal rules, or do they exist as a guide for treaty interpretation that is a normative act of fundamentally discretionary character? A critical analysis of the existing discourse on treaty interpretation shows that the Vienna rules function and exist as a guide, rather than strictly binding legal rules, for treaty interpretation. In other words, the Vienna rules are the flexible and practical guide based on the essentially binding legal principle of good faith. This view is consistent with how the rules actually work. The gap between the normative anointment and the actual existence could be explained in part by the insight or assumption suggested by the legal realism.
The above discussion on the formation of the Vienna rules, their substantial status, and the gap between appearance and substance leads to the concluding observation that travaux preparatoires, despite its designation as supplementary means in Article 32, possesses de facto parity as an element of treaty interpretation under the Vienna rules. Travaux preparatoires has been practically accepted as one of those equally important major elements of treaty interpretation in the actual practice of modern international law including the jurisprudence of the ICJ. Despite their official characterization as customary international law, the Vienna rules are regarded and function as a flexible guide or a signpost. Contrary to what the hierarchical structure of the Vienna rules suggests, travaux preparatoires is not confined to being supplementary, auxiliary, secondary or subsidiary. In light of what may be called the sequential and parallel pattern of application of the Vienna rules found mainly in modern jurisprudence of the ICJ, preparatory work has de facto equal value as other elements of treaty interpretation such as ordinary meaning, context, object and purpose, subsequent agreement and practice, etc. The factors behind such de facto parity may include: the requirement of persuasiveness and acceptance of international adjudication; the inherent preference of sovereign states for preparatory work; and the very nature of legal dispute on treaty interpretation.
It is true that there are certain limits to the thesis of de facto parity such as heavy reliance on the jurisprudence of the ICJ, and potential mutability. This thesis, however, may serve as a useful vantage point for gap between norm and reality. Also, the theoretical and practical implications of the thesis are not inconsequential: it predicts potential preponderancy of certain pattern of argumentative structure over others in treaty interpretation (that is, the sequential, overlapping confirmation by each element will probably work better); and it reconfirms the importance of the overarching principle of good faith in treaty negotiation and interpretation.
In this context, a case study is presented to highlight the critical importance of in-depth examination of travaux preparatoires in understanding legal issues involving interpretation of major international agreements to which Korea is a party.
