d'Aspremont: The Custom-Making Moment in Customary International Law

Jean d'Aspremont (Sciences Po - Law; Univ. of Manchester - Law) has posted The Custom-Making Moment in Customary International Law (in The Theory and Philosophy of Customary International Law and Its Interpretation, Panos Merkouris, Jörg Kammerhofer, & Noora Arajärvi eds., forthcoming). Here's the abstract:

This short chapter argues that, in international legal practice and literature, the actual moment where social reality has engendered a customary norm is never established or traced, but, rather, is always presupposed. According to the argument developed here, the moment custom is made is located neither in time nor in space. Custom is always presupposed to have been made through actors’ behaviors at some given point in the past and in a given place but neither the moment nor the place of such behaviors can be found or traced. In other words, there is never any concrete moment where all practices and opinio juris coalesce into the formation of a rule and which could ever be “discovered”. This means that the behaviors actually generating the customary rule at stake are out of time and out of space. Because the custom-making moment is out of time and space, it cannot be located, found, or traced, and it must, as a result, be presumed.

This brief chapter first sketches out some of the main manifestations of this presumption of a custom-making moment. It then sheds light on some of the discursive consequences of presuming a custom-making moment, including those consequences for the interpretation of customary international law.