Self-defence in international law

Hugo Grotius, the 17th century jurist and father of public international law, stated in his 1625 magnum opus The Law of War and Peace that "Most Men assign three Just Causes of War, Defence, the Recovery of what's our own, and Punishment." Article 2(4) of the UN Charter requires that: All Members shall refrain in their international relations from the threat or use of force against the territorial integrity or political independence of any state, or in any other manner inconsistent with the purposes of the United Nations. The drafters intent was that collective force approved and organized by the Security Council would substitute for unilateral uses of force by states. However, some states were concerned that use of the veto power by one of the Council's permanent members might prevent that body from taking necessary action, and they insisted upon inserting into the Charter an explicit right of self defense. Article 51 of the UN Charter states the following: Nothing in the present Charter shall impair the inherent right of collective or individual self-defense if an armed attack occurs against a member of the United Nations, until the Security Council has taken the measures necessary to maintain international peace and security. Measures taken by members in exercise of this right of self-defense shall be immediately reported to the Security Council and shall not in any way affect the authority and responsibility of the Security Council under the present Charter to take at any time such action as it deems necessary in order to maintain or restore international peace and security. International law recognizes a right of self-defence, as the International Court of Justice (ICJ) affirmed in the Nicaragua Case on the use of force. Some commentators believe that the effect of Article 51 is only to preserve this right when an armed attack occurs, and that other acts of self-defence are banned by article 2(4). Another view is that Article 51 acknowledges the previously existing customary international law right and then proceeds to lay down procedures for the specific situation when an armed attack does occur.