Introduction

Of all the contentious aspects of the emerging international investment treaty law, none appears to generate as much controversy as the scope of Most Favored Nation ("MFN") clauses. Investment treaty MFN clauses generally guarantee investors the best treatment offered by the host state to investors in any third country. The scope of such clauses was considered in the first investment treaty case at the ICSID, AAPL v. Sri Lanka.[1] After noting that "[t]he most-favored nation provision contained in Article 3 ... may be invoked to increase the host State's liability in case a ...