On 30 May 2016, the International Law Commission (‘ilc’) adopted a set of 16 Draft Conclusions providing a methodology on how to identify customary international law. Although largely based on the two elements approach set forth in article 38(1)(b) of the Statute of the International Court of Justice, the ilc study pushes the boundaries of the formal sources of international law beyond the realm of state practice by recognising that the practice of international organizations (‘ios’) as such may be constitutive of custom. This article critically examines the ilc Draft Conclusions concerning the role of ios in the process of custom creation. It examines the concept of resolution adopted by the ilc and assesses the coherence of the interpretive methodology devised by the ilc using the un General Assembly resolutions as a case study. The findings show that the Draft Conclusions fall short of expectation in providing authoritative guidance to scholars and practitioners alike.