Vincy Fon, Francesco Parisi
Date Posted: 2003
While customary law is capable of creating universally binding rules, the rules that govern its formation allow states to gain an exemption from emerging norms of customary law by remaining persistent objectors. This form of objection requires the objecting state to take express action to oppose an emerging practice by making its objections widely known before the practice solidifies into a binding rule of custom. Likewise, after the custom is formed states have an opportunity to express an objection or depart from it. In this latter case, the departing state does not obtain an exemption from the binding custom unless other states acquiesce to its departure. We model the effects of persistent objector and subsequent objector doctrines in the formation and change of customary law when heterogeneous states are involved.