Public International Law
Published 15 Feb 2017
By overwhelming weight of authority the law proscribing the use of force against another State can be found in Article 2(4) of the Charter of the United Nations: 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 restriction on the use of force is couched in general terms, and is inclusive of all forms of military action and/or harmful actions short of war. In Corfu Channel Case (United Kingdom v. Albania), the International Court of Justice noted that the prohibition was sufficiently broad as to cover all applications, even if the action was a unilateral act for the benefit of the international community as the act would undermine territorial sovereignty in these words:
The United Kingdom has stated that its object was to secure the mines as quickly as possible for fear lest they should be taken away by the authors of the mine-laying or by the Albanian authorities… as a new and special application of the theory of intervention, by which the intervening State was acting to facilitate the task of the international tribunal, or as a method of protection or self-help… As regards the notion of self-help, the Court is unable to accept it: between independent States the respect for territorial sovereignty is an essential foundation for international relations.
The wide scope of this prohibition as to the weapons considered is made clear in Paramilitary Activities in and against Nicaragua (Nicaragua v. United States of America), where restitution was sought from the United States for support that the United States extended to a proxy paramilitary organization based in Honduras and Costa Rica whose objective was to overthrow the socialist Nicaraguan government, where the Court held:
These provisions (referring to the law on the use of force in the UN Charter) do not refer to specific weapons. They apply to any use of force, regardless of the weapons employed. The Charter neither expressly prohibits, nor permits, the use of any specific weapon, including nuclear weapons.
Although the provision is included in the UN Charter and makes reference to States-parties, the prohibition extends to all States as members of the international community as the prohibition exists as a customary rule. In Paramilitary Activities in and against Nicaragua (Nicaragua v. United States of America, Judge Sette-Camara had this to observe in a concurring opinion:
The non-use of force as well as non-intervention – the latter as a corollary of equality of States and self-determination – are not only cardinal principles of customary international law but could in addition be recognized as peremptory rules of customary international law which impose obligations on all States.
The prohibition on the use of force outside of these parameters is not absolute. The UN Charter itself, in Article 51 recognizes the inherent right of a State to self-defense. The exclusion under this article is couched in these terms:
Nothing in the present Charter shall impair the inherent right of individual or collective self-defence if an armed attack occurs against a Member of the United Nations, until the Security Council has taken measures necessary to maintain international peace and security. Measures taken by Members in the exercise of this right of self-defence 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.
Under the right to self-defense, a State may unilaterally use force in either individual or collective self-defense as described in Article 51 of the United Nations Charter.
Nothing in the present Charter shall impair the inherent right of individual or collective self-defence if an armed attack occurs against a Member of the United Nations, until the Security Council has taken measures necessary to maintain international peace and security.
However, for the State to be able to exercise this right, this must be exercised in accordance with the provisions of the said article. The article goes on to require that any and all such acts taken in the exercise of this right to self-defense must be immediately reported to the Security Council for it to take the appropriate steps necessary to restore international peace and security in these terms:
Measures taken by Members in the exercise of this right of self-defence 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.
The principles governing the use of force also justify its exercise under the principle of Humanitarian Intervention. The principle of Humanitarian Intervention maintains that “when a State commits cruelties aganst and persecution of its nationals in such a way as to deny their fundamental human rights and shock the conscience of mankind, intervention in the interest of humanity is legally permissible.
Aside from serving as the framework through which unilateral actions of one State may be evaluated as to whether or not such acts violate public international law, the United Nations also has an oversight function to ensure that acts contrary to public international law that can be considered as a threat to peace are not done with impunity by the offending State through the mandate of the UN Security Council. The UN Security Council is tasked with the determination of whether there exists a threat to peace through acts of aggression from a belligerent State, whose power is found in the words of Article 39 of the United Nations Charter in these words:
The Security Council shall determine the existence of any threat to the peace, breach of the peace, or act of aggression and shall make recommendations, or decide what measures shall be taken in accordance with Articles 41 and 42, to maintain or restore international peace and security.
The UN Security Council therefore has power to authorize a member state to use force in an action that would otherwise be illegal if only to maintain international peace and security.