José E. Alvarez

For those following debates on the merits of the investment chapters within the Trans-Pacific Partnership (TPP) and the Trans-Atlantic Trade and Investment Partnership (TTIP), the answer to the titular question is obvious. Investor-State Dispute Settlement (ISDS) is undoubtedly a mechanism to resolve “public law” disputes. This is a major reason why many, from the EU to the UN’s Independent Expert on the Promotion of a Democratic and Equitable International Order, want to replace ISDS with an international investment court, and also why U.S. Senator Elizabeth Warren was able to find one hundred U.S. law professors to sign a public letter in support of the view that ISDS is such a wrongheaded attempt to “privatize” what should stay in the “public” domain that it violates the rule of law. The public nature of the international investment regime, including ISDS, is taken for granted, particularly since there is no doubt that investor-state arbitrators apply public international law and that the international investment regime shares numerous points of intersection with other public international law regimes. This essay critically examines the consensus that ISDS is “public” and what is commonly meant by that characterization. It concludes that, for purposes of description and prescription, ISDS, and the regime of which it is a part, should best be seen as a hybrid between public and private.