Introduction

The jurisdictional award in Maffezini v. Spain [1] has loomed large in investment treaty arbitration decisions and in related scholarship since the decision was published 11 years ago. No fewer than 14 investment treaty arbitration decisions published after Maffezini address the interplay between MFN provisions and dispute resolution mechanisms. Several of these tribunals have relied explicitly on the Maffezini reasoning, using most-favored-nation ("MFN") clauses to allow investors to take advantage of more favorable dispute resolution provisions in third treaties,[2] ...