ARTICLE TEXT

Can a small state take a superpower to court and win? In Military and Paramilitary Activities in and against Nicaragua, decided on 27 June 1986, the International Court of Justice held that the United States had violated international law through its support for armed rebels in Nicaragua and its attacks on Nicaraguan ports and installations. Although the United States refused to take part in the merits phase and never complied, the judgment became the leading authority on the law of force.

The Background

After the Sandinista revolution of 1979, the United States accused Nicaragua’s new government of supplying arms to rebels in neighbouring El Salvador. From 1981, the United States supported the contras, armed groups fighting the Nicaraguan government, with funding, training, weapons and intelligence. In early 1984, mines were laid in Nicaraguan ports, and attacks were carried out on ports and oil installations.

On 9 April 1984, Nicaragua filed an application with the ICJ. The United States argued that the Court had no jurisdiction. On 26 November 1984, the Court held that it did, based on both states’ declarations accepting the Court’s compulsory jurisdiction and on a 1956 treaty of friendship between them. The United States then withdrew from the proceedings and later terminated its acceptance of the Court’s compulsory jurisdiction.

Why Customary Law Mattered

A reservation in the US declaration excluded disputes under multilateral treaties unless all affected parties to the treaty were before the Court. This meant the Court could not apply the UN Charter directly. Instead, it applied customary international law, holding that the prohibition of force and the right of self-defence exist in custom alongside the Charter. That required the Court to explain how customary rules are identified, and its analysis of state practice and opinio juris, the belief that a practice is legally required, became a classic statement of the method.

The Decision

In its principal findings, most adopted by twelve votes to three, the Court held that the United States had breached its obligations under customary international law. By training, arming, equipping, financing and supplying the contras, it had violated the principle of non-intervention in another state’s affairs. By its attacks on Nicaraguan ports and oil installations and by laying mines, it had used force against Nicaragua and violated its sovereignty. The mining, carried out without warning, also breached obligations towards shipping. The Court also found breaches of the 1956 treaty.

The Court rejected the US argument of collective self-defence on behalf of El Salvador, Honduras and Costa Rica. Self-defence under customary law requires an armed attack. The Court drew a distinction between the most grave forms of the use of force, which constitute an armed attack, and less grave forms. Supplying weapons or logistical support to rebels in another state might be an unlawful use of force or intervention, but it was not an armed attack giving rise to a right of self-defence. The Court also noted that the states said to be victims had not declared themselves attacked or asked for help at the relevant time.

Finally, the Court held that the conduct of the contras themselves was not attributable to the United States. Despite heavy US support, it had not been shown that the United States had effective control over the particular operations in which violations of humanitarian law were alleged to have occurred. This effective control test remains central to the law of state responsibility.

The Aftermath

The United States ignored the judgment and vetoed a Security Council resolution calling for compliance. The Court’s phase on reparation never concluded. After a change of government, Nicaragua discontinued the case in 1991.

Why It Matters

Nicaragua is essential reading on the prohibition of force, the gravity threshold for armed attack under Article 51 of the UN Charter, the principle of non-intervention and the attribution of conduct to states. Its effective control test was later contrasted with the looser overall control test of the International Criminal Tribunal for the former Yugoslavia in Tadić (1999), and reaffirmed by the ICJ in the Bosnian Genocide case (2007). For students, it is also a sobering lesson in the limits of international adjudication: a court can declare the law, but it cannot always make powerful states obey it.

Sources

1. ICJ, Military and Paramilitary Activities in and against Nicaragua, case page: https://www.icj-cij.org/case/70
2. ICJ, Summary of the Judgment of 27 June 1986: https://www.icj-cij.org/case/70/judgments
3. UN Office of Legal Affairs, Summaries of Judgments of the ICJ 1948–1991: https://legal.un.org/icjsummaries/