The profound change that has gripped the international legal system, as a result of the prohibition of the use of inter-State force and the criminalization of aggressive war, raises searching questions in regard to a number of concepts and institutions rooted in the obsolete axiomatic postulate that States are free to commence hostilities at will. It is true that, in some measure, the international community has already adjusted itself to the new legal environment. This is manifest, for instance, in the current invalidity of peace treaties dictated by the aggressor to the victim of aggression (see supra, ch. 2, B (a), (iii)). But modification of timehonoured doctrines encounters intractable difficulties in many areas.

The need for adaptation of the law to the present status of inter-State force is adumbrated against the silhouette of the antiquated perception of the two antagonists in war (aggressor and victim) as intrinsically equal in legal standing. It is noteworthy that, as pointed out already by Grotius, the Latin word bellum is derived from the more ancient term duellum. For centuries, international law treated war in the samemanner that domestic law used to deal with the duel. War, like a duel, was viewed with toleration. The parity of the contenders was taken for granted, and the sole concern was about adherence to criteria of ‘fair play’. Yet, just as the duel is no longer permitted by national legal systems, war is now forbidden by international law.