The lecture addresses the International Law Commission (ILC)’s work on ‘Identification of customary international law’, with particular reference to human rights law. In 2016, the ILC adopted 16 draft conclusions, with commentaries. Draft conclusion 2 confirms the two-element approach (a general practice; acceptance as law). It is sometimes asserted rules of human rights are ‘special’, and that different criteria for the formation and identification of customary international law in this field are thus in order. In particular, it is sometimes suggested that in the field of international human rights law, one element may suffice in constituting customary international law, namely opinio juris. But this cannot be the case as long as we are dealing with what properly may be called “customary international law”. There may, however, be a difference in the application of the two-element approach. Among other issues discussed are the role of international organizations; the relationship between customary international law and treaties: the effect of resolutions of international organizations; judicial decisions and teachings; the persistent objector; and particular customary international law.

After the lecture (on 27 June 2016), the International Law Commission adopted the 16 draft conclusions on ‘Identification of customary international law’, together with their accompanying commentaries, on 5 and 8 August 2016. They may be found in the ILC’s Report on the Work of its Sixty-Eighth Session (2016), UN Doc. A/71/10, at 79-117, available online at http://legal.un.org/ilc/reports/2016/. The talk has been slightly updated to take this into account

This WP is based on Sir Michael Wood's Distinguished Lecture at the 2016 Human Rights Summer Course held on 27 June 2016 at the European University Institute in Florence.