The International Law Commission (ILC) decided in 2012 to add to its agenda a new topic on the “identification of customary international law” and to appoint Sir Michael Wood (United Kingdom) as special rapporteur. That project has reached an important point, with a series of Draft Conclusions having been cleared through the Commission’s Drafting Committee, and ready for the Commission’s provisional approval (together with commentaries) in 2015. As such, now is a propitious time for governments, international organizations, nongovernmental organizations, scholars, and others to weigh in on the merits of these Draft Conclusions, and additional ones that will be developed in 2015–16.

It is widely acknowledged that international organizations (IOs) indirectly affect customary international law by catalyzing and focusing State practice. But next year the International Law Commission and Michael Wood, its Special Rapporteur on the Identification of Customary International Law, are primed to address a more contentious issue: when and how IOs can directly contribute, like States, to custom.

This past summer the Commission’s Drafting Committee provisionally adopted a draft conclusion stating that “[i]n certain cases, the practice of international organizations also contributes to the formation, or expression, of rules of customary international law.” Based on Wood’s Second Report dated May 2014, three topics merit particular attention in the year ahead: 1) distinguishing State practice from IO practice, 2) scrutinizing potentially relevant types of IO practice, and 3) considering types of cases in which such IO practice might contribute to custom. (While the Drafting Committee declined to include definitions in its draft conclusions, this article defines “IO” as Wood did in his Second Report: “an intergovernmental organization.”)

Customary international law often seems like a riddle wrapped in a mystery inside an enigma. According to Manley O. Hudson, even the drafters of the International Court of Justice Statute “had no very clear idea as to what constituted international custom.” The situation has not changed much since then.

I got my first taste of the difficulties in identifying custom when I was a junior attorney at the U.S. Department of State and was assigned the task of preparing the U.S. submission in a juvenile death penalty case before the Inter-American Commission on Human Rights. The juvenile death penalty is prohibited by the International Covenant on Civil and Political Rights (ICCPR) and the American Convention on Human Rights, but the question in the Inter-American Commission case was whether it is also prohibited as a matter of customary international law.

The International Law Association’s Statement of Principles Applicable to the Formation of General Customary International Law (2000) was a welcome addition to an admittedly voluminous literature. Stepping into the void of authoritative commentary, it balanced an estimable representation of contemporary thinking while it also tendered sometimes controversial views on unresolved matters. Though nominally on the same subject, the International Law Commission (ILC) project offers different strengths and faces different challenges. As the First Report by the Special Rapporteur, Sir Michael Wood, has noted, the ILC’s relationship with States, in particular, provides it with a special vantage and authority. This vantage may also make its pronouncements less tendentious, and more conservative, in character. I’d like to assess the (very early) returns on how this potential differentiation is faring. For sake of brevity, I will focus mostly on a likely harbinger, the treatment of State practice, as reflected in the Draft Conclusions already adopted by the Drafting Committee—including parts of the Second Report bearing upon them. Any stylistic or substantive criticism of the existing work recognizes, of course, that it is at an early stage, and that one of ILC’s many virtues is the deliberate and careful evolution of its projects.

A primary goal of the International Law Commission’s work on the identification of customary international law is to offer “guidance to those called upon to identify the existence of a rule of customary international law,” particularly national court judges. The ILC report, however, should be no less useful to participants in international adjudication. The report’s impact might be particularly significant in investment arbitration, which, given the field’s growing importance and impact, could greatly facilitate the ILC’s principal mandate of promoting the “progressive development of international law.”

Investment arbitration is proving hugely significant for the development of international law. The United Nations Conference on Trade and Development reported that, at the end of last year, there were 568 known cases brought under international investment agreements, including 57 cases brought in 2013 alone. There have been 98 different State respondents, including the United States, which reportedly is the ninth most frequent respondent State.

This Commission project is a useful one. It rests on exemplary work by the Special Rapporteur. I would hope that brief mention of a few matters that may benefit from further reflection at this stage could be of some assistance as work on this matter continues.

We are grateful to AJIL Unbound for organizing this symposium on the work of the International Law Commission on identification of customary international law. We are particularly grateful to all who have contributed to the symposium for their interest and insights.

We shall not here reply comprehensively to everything that has been said. Many points will be addressed in the Special Rapporteur’s third report, to be submitted to the UN Secretariat toward the end of March 2015 in preparation for the Commission’s session beginning in May 2015. We would only say that many of the points made in the symposium thus far seem eminently sensible, and will hopefully be seen as such by the Commission. It has to be noted, however, that the work of the Commission is collegiate, and the eventual output does not belong to the Special Rapporteur (who is just a facilitator) but to the Commission as a whole—and eventually to the General Assembly and the international community.

In this contribution to AJIL Unbound, I outline a moral judgment-based account (MJA) of customary inter-national law. On the MJA, moral judgment plays a dual role in the formation of customary international law. First, MJA is part of a disjunctive analysis of opinio juris, which involves a moral judgment about what the law ought to be or what it justifiably is. Second, the interpretive process of adducing a customary norm from state practice and opinio jurischaracteristically requires some moral judgment on the part of the interpreter. Along the way, I draw attention to two points at which the MJA departs significantly from the analysis presented in the International Law Commission (ILC)’s Second Report by Special Rapporteur Sir Michael Wood, on the identification of customary international law.1 First, by more sharply separating state practice from opinio juris, MJA avoids systematically double-counting the same facts as both opinio jurisand state practice. Second, MJA offers an effective response to the so-called “paradox of custom”, according to which a customary norm can only come into existence if a sufficient number of states mistakenly believe (or pretend to believe) that it already exists.