Author(s): Esme Shirlow
Materials produced during the negotiation of treaties, commonly called travaux préparatoires, are given formal significance as a ‘supplementary means’ of treaty interpretation under article 32 of the Vienna Convention on the Law of Treaties (‘VCLT’). Travaux present both risks and opportunities for treaty interpretation, and international adjudicators have differed in how they define the rationale for referring to travaux; how they use these materials, and even more fundamentally, what materials they classify as travaux. This article proposes a methodology to guide the more structured identification and use of travaux. The article uses the interpretation of investment treaties in investor-state arbitration as a case study to illustrate the proposed approach and its utility. The discussion, including the proposed sliding scale approach, is nonetheless equally relevant for interpreting all manner of treaties. Section I illustrates three practical challenges associated with the use of travaux in investment treaty disputes to highlight the advantages and pitfalls associated with using travaux. Section II considers what may constitute ‘travaux’. Based on an extensive review of arbitral practice, Section II argues in favour of a sliding scale approach to travaux, whereby treaty interpreters assess the utility of a given material by reference to its precise qualitative features and the context of interpretation. Section III considers how arbitral tribunals have used – and should use – travaux by reference to the interpretive framework established by the VCLT. Section IV considers how investment tribunals have regulated access to and use of travaux through their powers to order document production.