 Difficulties with consent-based, or voluntarist, theories have led to the exploration of alternative bases for the legitimacy of international law, especially in relation to those obligations not traceable to a treaty. The two following approaches are not only non-voluntarist, but they also make reference to objective standards of reason. One approach is inspired by Joseph Raz’s influential “service conception of authority”, which advances a Normal Justification Condition (NJC) on legitimate authority. According to the NJC: