The rules governing resort to force form a central element within international law, and together with other principles such as territorial sovereignty and the independence and equality of states provide the framework for international order. While domestic systems have, on the whole, managed to prescribe a virtual monopoly on the use of force for the governmental institutions, reinforcing the hierarchical structure of authority and control, international law is in a different situation. It must seek to minimise and regulate the resort to force by states, without itself being able to enforce its will. Reliance has to be placed on consent, consensus, reciprocity and good faith. The role and manifestation of force in the world community is, of course, dependent upon political and other non-legal factors as well as upon the current state of the law, but the law must seek to provide mechanisms to restrain and punish the resort to violence.

Law and force from the ‘just war’ to the United Nations

The doctrine of the just war arose as a consequence of the Christianisation of the Roman Empire and the ensuing abandonment by Christians of pacificism. Force could be used provided it complied with the divine will. The concept of the just war embodied elements of Greek and Roman philosophy and was employed as the ultimate sanction for the maintenance of an ordered society. St Augustine (354–430) defined the just war in terms of avenging of injuries suffered where the guilty party has refused to make amends.