This paper argues that the concerns and methodology of the recently completed Report of the International Law Commission (ILC) over the fragmentation of international law presuppose a particular way of understanding legal language which tends to separate the understanding of rules from their factual adaptability to certain recurring social problems faced within specific institutional contexts. The paper argues that separating rules from their factual adaptability focuses the analysis on surface coherence – coherence at the level of abstract terms and phrases. It is the argument of this paper that this presupposition is not warranted, and that the understanding of rules cannot be thus separated. An alternative model of the understanding of legal language is developed on the basis of the work of Bernard Jackson and Geoffrey Samuel. This is further supplemented by the approach to the study of institutional contexts in the recent work of Robert Summers and John Bell. Together, these resources can lead to the analysis of the deep coherence of the international legal order, that being one that prioritizes not the unity of that order, but its responsiveness. The ideal of responsive law is elaborated upon by reference to the work of Philip Selznick and Philippe Nonet. Finally, a different agenda for the ILC is offered on the basis of the methodology of deep coherence. The upshot is that the paper calls for a reorientation of international legal theory, away from concerns about ‘the law itself’ and towards an engagement with the responsiveness of legal work performed in international legal institutions.