Divided but harmonious? The interpretations and applications of article 31(3)(c) of the vienna convention on the law of treaties

In response to an anxiety about the multiplication of special regimes, international lawyers looked towards Article 31(3)(c) of the Vienna Convention of the Law of Treaties to help sustain the unity of international law. Suppose though that the provision is as susceptible to fragmentation as any other rule; its interpretation and application may fall victim to the narrow interests of the regimes it is meant to harmonise with the rest of international law. This article thus analyses various judicial decisions to measure the extent to which fora have conflicted in ascertaining the normative content of Article 31(3)(c). Using strict and relaxed definitions of jurisprudential conflict, the article concludes that, in both cases, the interpretations and applications of the provision remain coherent, but with some key qualifications.