Introduction

Investment treaties tend to say nothing, or only very little, about the appropriate standard of review for arbitrating disputes between sovereign states and foreign investors. Most treaties do not address whether states should be afforded any deference in their own assessment of their treaty obligations. Neither do they specify the converse, that state action must be strictly reviewed. They are simply silent-and their silence has been interpreted in innumerable ways by different tribunals. This interpretive chaos has generated calls for a unified approach-one that would resolve ...