International Investment Law and the Public Law Analogy: The Fallacies of the General Principles Method

Over the past ten years, commentators have drawn an analogy between the international investment regime and domestic public law in order to fill gaps, resolve ambiguities, and understand the nature of the investment regime. One way in which domestic public law may be relevant is if it reflects a general principle of law that is applicable by virtue of Article 31(3)(c) of the Vienna Convention on the Law of Treaties. The practice of international investment tribunals demonstrates, however, that tribunals do not use domestic law according to the ‘general principles method’. Instead, investment tribunals’ use of comparative law raises various normative and methodological issues that have not yet been thoroughly addressed in the literature. The article identifies and addresses some of those issues.