The Sources of International Investment Law

Abstract

This chapter addresses the challenges posed by the practice of international investment law to the conventional theory of the sources of international law. After a brief overview of what is generally understood as the main ‘sources’ of ‘international investment law’ (II), I examine in turn three challenges to this basic understanding, which arise from the need to account for the domestic laws governing different aspects of foreign investment transactions (III), the detailed jurisprudential norms generated by investment tribunals to specify broadly formulated norms, particularly investment treaty provisions (IV), and the norms of general international law expressing the sovereignty of the State (V). For each category of norms I select a number of problems that put the most widely accepted understanding of the sources of international law to test, and I explain why the problems examined, far from mere academic points, have potentially important practical implications. I conclude with some observations on the interactions between practice and the theory of the sources of international law (VI).

Keywords: sources of international law, international investment law, domestic law, sovereignty, precedent, investment arbitration jurisprudence