1 Introduction – 2 The MFN clause under international investment agreements – 2.1 Overview – 2.2 Recent Trends in MFN drafting in treaty making – 2.3 The relevance of MFN clauses to IIL – 2.4 MFN clauses and ISDS – 3 The importance of prior requirements to ISDS in international investment law – 4 Alternative dispute settlement mechanisms and MFN clauses: the Argentinian experience – 4.1 The UNASUR Centre for the Settlement of Investment Disputes – 4.2 Recent BITs – 5 Interpretation of MFN Clauses: the Argentinian Experience – 5.1 Local Litigation Requirements in Argentinian IIAs – 5.2 Case Law – 5.2.1 The use of MFN provisions to disregard the prior local litigation requirement – 5.2.2 A more careful consideration to the MFN clauses – 5.2.3 More recent interpretations of MFN clauses and the way forward – 5.2.3.1 Ablacat v Argentina – 5.2.3.2 Hochtief v Argentina – 5.2.3.3 Urbaser v. Argentina – 5.2.3.4 The way forward – 6 Conclusion – References.