Debating Interpretation:On the Road to Ithaca

In the articles published in the Leiden Journal of International Law (LJIL) and irrespective of the topic analysed, a theme that is touched upon time and time again is that of interpretation. Similarly, in recent years both the International Law Commission (ILC) and the Institut de Droit International (IDI) have devoted part of their work and the expertise of their members to addressing topics directly tied to interpretation. The ILC, for instance, in 2018 produced a set of Draft Conclusions with commentaries on ‘Subsequent agreements and subsequent practice in relation to interpretation of treaties’. Along the same vein, the IDI in the summer of 2021 published a report on the topic of limits to the dynamic interpretation of the constitutive instruments of international organisations by their internal organs. In addition to these, there have been several topics that in some shape or form share a connection with interpretation, as is, for instance, the case with the ILC’s work on ‘Unilateral Acts of States’, ‘Identification of Customary International Law’, ‘Jus Cogens’, and the ‘Immunity of State Officials from Foreign Criminal Jurisdiction’. Despite the ubiquity of interpretation in all fields of public international law, the nature, function and content of its rules is still debated. So much so, in fact, that even whether in the case of interpretation we can talk about ‘rules’ in a strict sense, is also contested. It has been argued that it is more appropriate to refer to these ‘rules’ as ‘principles’, ‘canons’, ‘maxims’, or simply ‘methods’, with all the accompanying baggage that such terms come with regarding the normativity of the thing they attempt to describe. Does this variety of theoretical approaches to interpretation and its ‘rules’ have any effect on the value of the discussions surrounding their content, such as the recent efforts of the ILC and the IDI? The aim of the thoughts put down in the following pages is to demonstrate that irrespective of where one stands on the spectrum of the debate on the ‘rules’ of interpretation, we can only benefit from the continuation of this discussion. Section 2 will discuss that the Vienna Convention on the Law of Treaties (VCLT), and its Articles 31-3, have contributed to the adoption of a common vocabulary on which interpretative arguments are constructed. This common vocabulary has had as a consequence the refinement of interpretative argumentation and an increased emphasis of international courts and tribunals on providing more detailed explanations of the steps of their interpretative reasoning (often based on the VCLT structure and vocabulary). Even when such reasoning is flawed (Section 3) the ability to identify such flaws, which stems from both the common vocabulary and the more detailed reasoning, is in and of itself an important benefit, as it can further the discussion and refinement of the rules of interpretation. As Section 4 will illustrate there is still a plethora of issues surrounding the content of the rules of interpretation that are still to be resolved, and many more yet to uncover. It is through this continuous process of debate and refinement that we have the most to gain, in understanding not only the rules of interpretation but international law as a system as well.