For international lawyers, the Vienna Convention rules of treaty interpretation are ‘the only game in town’, they have had the whip-hand for several decades now. Yet is this belief in the power(s) of the Vienna rules justified? Behind the claim that they are the law lies a theoretically much more interesting, yet fundamentally unsustainable second argument. It is that rules of interpretation are somehow independent of – and replace – the legal epistemic process, the ascertainment of the law’s meaning-content. These rules are seen as serving a different function, i.e. to regulate the process of the applicative construction of meaning by the organs of international law. They are doctrine’s attempt to control how treaties are construed by tribunals. However, as a matter of legal theory there are severe limits to what such rules can do. Given these limits, we will reconstruct the possible meanings and uses of the Vienna Convention rules.