International custom formation : Synthesis of traditional theories

Abstract

The two elements of custom: usage ―the material and detectable element‖ and opinio iuris, the ―immaterial and psychological element‖ have been offered by François Geny. These two elements form the core of traditional theories concerning custom formation and thus the object of analysis in the present study. The first part approaches the material element of the custom, emphasising different views regarding its four requirements: duration, repetition, continuity generality and uniformity. The second part approaches the psychological element of the custom through the most important theories concerning it: the error hypothesis, the consent, acquiescence and lack of protest hypothesis.