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Abstract

Recent developments in investor-state arbitration portrays most-favoured-nation (MFN) standard as a limitless provision to attract third party treaties. There is no jurisprudence constante as to its nature and scope under international investment law. Textual differences of the clause in investment treaties are often used as a justification for its varied interpretation by ad hoc arbitral tribunals. On that account, this article identifies specific interpretative techniques—like res inter alias acta, ejusdem generis, questioning presumptive approaches, recognising relative autonomy of treaty components, and balancing conceptual evolution over textual interpretation—to ascertain the limits of MFN standard under international investment law and to regulate the interpretative discretion of investment tribunals.

Keywords: investment law, mfn clause, interpretative principles, res inter alias acta, ejusdem generis, concept of treatment, dispute settlement, relative autonomy of treaty components, presumptive approach