An estimated that 96% of all war-related deaths occurred in the Modern period between 1500 and 2000, with the 20th century alone, marked by the chaotic violence of the First and Second World Wars, accounting for approximately 73% of all war-related deaths throughout history.1 Given such blood-spattered pages of modern history, the modern proliferation of international law is unsurprising. Nor is it surprising that a prohibition on “the threat or use of force against the territorial integrity or political independence of any state” (Article 2(4)) is among the first principles delineated in the UN Charter. Few wish to repeat the horrors of the 20th century. The noble virtues of a universal prohibition on the use of force, however, do little to inspire compliance when state interests are at stake. Of greater import is whether international law has the teeth to enforce Article 2(4), even when sovereign states choose to violate it. Part of the difficulty with conceptualizing international law enforcement is that it has no physical manifestation—no international police officers handing out tickets for violations, no international army sent by into countries which refuse to abide by their treaty obligations. Even so, international law possesses a number of mechanisms by which Article 2(4) may be—and has in the past been—enforced.
The UN Charter itself provides mechanisms for the support and enforcement of the Article 2(4) prohibition of the use of force. Chapter VI stipulates means for peaceful settlements of disputes, establishing the Security Council as the chief arbiter between disputing parties, capable of referring disputes of a legal nature to the International Court of Justice (ICJ). The case of Nicaragua v. United States of America, which concerned a dispute over the legitimacy of cross-border military and paramilitary activities, exemplifies the efficacy of legal arbitration to enforce international rules on the use of force.2 A use of force in violation of Article 2(4), however, often presupposes the inapplicability of a Chapter VI settlement. In such cases, the Chapter VII enforcement system may be triggered. Chapter VII grants the Security Council the power to employ direct action in response to “any threat to the peace, breach of the peace, or act of aggression” which cannot be settled peacefully (Article 39). Article 41 empowers the Security Council to impose economic sanctions, diplomatic sanctions, and the severance of all means of communication and transportation as a means of coercing cooperation with its mandates. Since 1966, the UNSC has established a total of 30 sanctions regimes, 14 of which are ongoing.3 The efficacy of such sanctions is debatable. A 2013 study reported that Security Council “[s]anctions were effective in coercing 10% of the time and in constraining and signaling in 27% of the cases,” with an overall effectiveness rate of 22%.4 These somewhat lacklustre numbers must, however, be considered in light of the multifaceted resolution strategies undertaken in response to a given conflict. Sanctions alone may exhibit limited success, but may prove more effective when paired with other enforcement and diplomatic measures.
If Article 41 sanctions prove inadequate to enforce an Article 2(4) violation, Article 42 provides for the use of military force, authorizing the Security Council to “take such action by air, sea, or land forces as may be necessary to maintain or restore international peace.” Due the refusal of member states to ratify Article 43 (which would have made members’ armed forces and facilities directly available to the Security Council), the Security Council is instead forced to rely on the voluntary contribution of military forces on a case-by-case basis.5 Seventy-six military missions were authorized by the UN between 1946 and 2000, excluding instances in which the Security Council authorized the use of force by NATO’s Operation Allied Force.6 Of these, two were in explicit response to Article 2(4) violations: the UN-commanded Korean operation from 1950-53 and the US-led coalition operation into Kuwait in 1990-1). Another twenty-four concerned the the use of force to “ensure compliance with international principles… and protect international legal principles.”7 No accessible study of UN military authorizations has been conducted since 2003, but, given the trajectory of increasing use of military force over time, the number of enforcement and compliance missions is likely considerable higher today.
In light of the legitimized uses of force under Chapter VII, it is apparent Article 2(4) is not a wholesale prohibition on the use of force. It is better understood as a prohibition on the unilateral use of force, the previously normative use of which has been superseded in international law by multilateral uses of force, carried out in the interest of collective peace and security, and authorized by the Security Council. Under the UN Charter, the legal use of force is reserved primarily to prevent and quell illegal uses of force. Thus, Article 51 grants that in the case of an armed attack, “nothing in the present Charter shall impair the inherent right of individual or collective self-defense… until the Security Council has taken the measures necessary to maintain international peace and security.” The right to employ military force, in addition to self-help countermeasures such as reprisals and retorsion, is implicit. It is under Article 51 that NATO also claims legitimacy, acting as an international enforcement body in response to attacks against its members, a commitment attested in Article 5 of the North Atlantic Treaty, and it has historically undertaken military operations both under and absent of Security Council authorization. Article 53 likewise empowers regional organizations to use force with Security Council authorization for the prevention of aggressive state policies. Enforcement of Article 2(4) is, therefore, inherent to the Charter itself.
Apart from inherent Charter enforcement mechanisms, Article 2(4) is additionally self-enforcing. Given the contractual and reciprocal nature of international law, it is in the national interest of states to comply with international legal rules in order to encourage the mutual compliance of other state actors. Violations of the legitimate use of force on one state’s part may well result in subsequent uses of force—authorized or unauthorized—against them. The universal membership of the UN further ensures that crucial political and legal legitimacy is bestowed on states which act in accordance with its principles.8 As a result, states are inlined to settle disputes peacefully, through the means provided in Chapter VI of the Charter, rather than resorting to the use of force.
Despite the inherent challenges in enforcing the Article 2(4) prohibition on the use of force, a number of enforcement mechanisms exist. Self-enforcement incentives encourage states to refrain from the use of force, absent of any coercive action. Disputes involving the use of force which might otherwise escalate further may be arbitrated by the ICJ. In the case of a violation of Article 2(4) which is unresolvable through peaceful or legal means, however, Chapter VII provides the Security Council with the authority to either impose diplomatic, communication, and economic sanctions on an aberrant state (Article 41), or to authorize the whatever use of force “necessary to maintain or restore international peace and security” (Article 42). Due to the lack of an international standing army, the execution of Article 42 is contingent upon the cooperation of member states on a case-by-case basis. Even so, the Security Council has not infrequently utilized the use of force to ensure compliance with international legal rules—including the prohibition on the use of force. Although the success rate of such missions has yet to be studied, it may reasonably be argued that Article 2(4) can, given appropriate enforcement strategies and cooperation by troop-supplying member states, be enforced as an international legal rule.
[1] William Eckhardt, “War-related Deaths Since 3000 BC,” Bulletin of Peace Proposals, December 1991, Vol. 22, No. 4 (December 1991): pp. 440.
[2] Military and Paramilitary Activities in and against Nicaragua (Nicaragua v. United States of America), Merits, Judgment. I.C.J. Reports 1986.
[3] UN Department of Political and Peacebuilding Affairs, Subsidiary Organs of the United Nations Security Council: 2022 Fact Sheets (23 February 2022), https://www.un.org/securitycouncil/sites/www.un.org.securitycouncil/files/subsidiary_organs_factsheets.pdf
[4] Thomas J Biersteker, Sue E Eckert, Marcos Tourinho and Zuzana Hudáková, “UN targeted sanctions datasets (1991–2013),” Journal of Peace Research, Vol. 55, No. 3 (May 2018), pp. 404-412.
[5] Charlotte Ku, and Harold Karan Jacobson, Democratic Accountability and the Use of Force in International Law (Cambridge ;: Cambridge University Press, 2003), 17.
[6] Ibid.
[7] Ibid., 23.
[8] Ibid., 352.
Bibliography
- Biersteker, Thomas J, Sue E Eckert, Marcos Tourinho and Zuzana Hudáková. “UN targeted sanctions datasets (1991–2013).” Journal of Peace Research, Vol. 55, No. 3 (May 2018): pp. 404-412.
- Eckhardt, William. “War-related Deaths Since 3000 BC.” Bulletin of Peace Proposals, December 1991, Vol. 22, No. 4 (December 1991): pp. 437-443.
- Katselli Proukaki, Elena. The Problem of Enforcement in International Law : Countermeasures, the Non-Injured State and the Idea of International Community. London: Routledge, 2010.
- Ku, Charlotte, and Harold Karan, Jacobson. Democratic Accountability and the Use of Force in International Law. Cambridge: Cambridge University Press, 2003.
- Military and Paramilitary Activities in and against Nicaragua (Nicaragua v. United States of America), Merits, Judgment. I.C.J. Reports, 1986.
- North Atlantic Treaty Organization. North Atlantic Treaty. 1 June 1949.
- UN Department of Political and Peacebuilding Affairs. Subsidiary Organs of the United Nations Security Council: 2022 Fact Sheets. 23 February 2022.
- United Nations, Charter of the United Nations, 1945, 1 UNTS XVI.