Maffezini v. Plama : Reflections on the Jurisprudential Schism in the Application of Most-Favored-Nation Clauses to Matters of Dispute Settlement

The paper discusses the diverging decisions of the investment treaty tribunals in Emilio Agustín Maffezini v. Kingdom of Spain and Plama Consortium Limited v. Republic of Bulgaria regarding the question of whether most-favored-nation (MFN) clauses in international investment treaties can apply to questions of dispute settlement procedure and arbitral jurisdiction. The aim of the article is not, however, to argue for one or the other side of the jurisprudential split (or schism). Instead, its objective is to reflect on the impact both Maffezini and Plama have had on the development of investment treaty arbitration and the challenges the jurisprudential split between these two landmark cases poses. After briefly describing and contextualizing both cases, the paper focuses on how the battle of precedent between Maffezini v. Spain and Plama v. Bulgaria has played out in subsequent case law and what it teaches us about the functioning of and challenges for investment treaty arbitration. It concludes with a reflection on the crucial impact of the decision-makers and their ideational or ideological allegiance to either line of precedent