Goodbye, Maffezini? On the Recent Developments of Most-Favoured-Nation Clause Interpretation in International Investment Law

Abstract

The article focuses on the development of post-Maffezini practice of interpretation and application of most-favoured-nation clauses in international investment law. Although such clauses differ as to their precise formulation, the traditional view was that they applied to substantive treatment only. The decision of the arbitral tribunal in Maffezini was a point of change that gave a new, unpredicted dynamic to the interpretation of mfn clauses in bits. The aim of this article is to shed a light on the development of international investment jurisprudence in order to confirm or to question the sustainable nature of the shift in interpretation of mfn clauses. The analysis also draws from the recent work of the Study Group of the un International Law Commission. Some recent and drafted investment agreements are also taken into consideration with a view to completing the interpretation of mfn clauses by investment tribunals and the ilc report.