Part V Treaty Interpretation, 20 The Interpretation of Treaties over Time

Subject(s):

Good faith — Vienna Convention on the Law of Treaties — Object & purpose (treaty interpretation and) — Ordinary meaning (treaty interpretation and) — Rules of treaty interpretation

This chapter considers an issue that has garnered sustained attention by States and international courts and tribunals in recent years — the potential to allow (or deny) evolutionary interpretations to treaty terms. It highlights five conclusions about the interpretation of treaties over time. First, evolutionary interpretations are made based on an array of means of ordinary interpretation, as enshrined in Vienna Convention on the Law of the Treaties Articles 31–33 and customary international law. Second, evolutionary interpretation is an issue of fact and law arising in the circumstances of particular cases. Third, the main principle is that of ‘contemporaneous interpretation’, a term referring not to the interpreter but to the parties (i.e. contemporaneous to the time of conclusion of the treaty). Fourth, it makes no sense to apply the principle of contemporaneity in all circumstances, since there are some terms used in treaties that make legal sense only when understood to evolve over time. Finally, to keep the unity of the treaty and its terms, the new interpretation is retrospective, having effect back to the time of the treaty’s conclusion.