Use of Force By States

The use of force by states is controlled by both customary international law and by treaty law. The UN Charter reads in article 2(4):

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.

This rule was "enshrined in the United Nations Charter in 1945 for a good reason: to prevent states from using force as they felt so inclined", said Louise Doswald-Beck, Secretary-General International Commission of Jurists.

Although some commentators interpret Article 2(4) as banning only the use of force directed at the territorial integrity or political independence of a state, the more widely held opinion is that these are merely intensifiers, and that the article constitutes a general prohibition, subject only to the exceptions stated in the Charter (self-defence and Chapter VII action by the Security Council). The latter interpretation is also supported by the historic context in which the Charter was drafted, the preamble specifically states that "to save succeeding generations from the scourge of war, which twice in our lifetime has brought untold sorrow to mankind" is a principal aim of the UN as such. This principle is now considered to be a part of customary international law, and has the effect of banning the use of armed force except for two situations authorized by the UN Charter. Firstly, the Security Council, under powers granted in articles 24 and 25, and Chapter VII of the Charter, may authorize collective action to maintain or enforce international peace and security. Secondly, Article 51 also states that: "Nothing in the present Charter shall impair the inherent right to individual or collective self-defence if an armed attack occurs against a state." There are also more controversial claims by some states of a right of humanitarian intervention, reprisals and the protection of nationals abroad.