ICJUse of forceInternational Court of Justice

Military and Paramilitary Activities in and against Nicaragua (Nicaragua v United States of America)

ICJ Reports 1986, p. 1419861 min read

The case in brief30-second read

Facts: Nicaragua brought proceedings against the United States, alleging the US had trained, armed, equipped, and directed Contra rebel forces against the Nicaraguan government.
Issue: Whether the ICJ had jurisdiction over the dispute, and whether the US violated customary international law by using force against Nicaragua and interfering in its internal affairs.
Held: Jurisdiction upheld based on the Optional Clause declarations and a 1956 US-Nicaragua Treaty of Friendship.
Principle: Customary international law prohibition on the use of force and non-intervention exists independently of the United Nations Charter; self-defence requires the attacked state to declare itself a victim

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Facts

Nicaragua brought proceedings against the United States, alleging the US had trained, armed, equipped, and directed Contra rebel forces against the Nicaraguan government
The US had also mined Nicaraguan harbours
The US denied ICJ jurisdiction and withdrew from proceedings after the jurisdiction phase
The case proceeded on merits without US participation

Issue

Whether the ICJ had jurisdiction over the dispute, and whether the US violated customary international law by using force against Nicaragua and interfering in its internal affairs.

Held

Jurisdiction upheld based on the Optional Clause declarations and a 1956 US-Nicaragua Treaty of Friendship
The US violated customary international law by:
Training and directing the Contras
Mining Nicaraguan ports
Directing attacks on Nicaraguan infrastructure

Ratio decidendi

Customary international law and treaty law can co-exist on the same subject matter. The prohibition on the use of force is not merely a Charter obligation but an independent rule of customary law. Self-defence under customary law requires proportionality, necessity, and a request from the attacked state. The ICJ has jurisdiction even when a permanent Security Council member refuses to participate.

Exam use

How to use it in an answer

Central case for essays on use of force, self-defence, non-intervention, and ICJ jurisdiction
Cite for the proposition that customary law exists independently of treaty law
Authority for conditions of collective self-defence
Key line: "The customary international law prohibition on the use of force exists independently of Article 2(4) of the UN Charter; self-defence requires that the attacked state declare itself a victim."

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Citation

Military and Paramilitary Activities in and against Nicaragua (Nicaragua v. United States of America) ICJ Reports 1986, p. 14

Reported: ICJ Reports 1986, p. 14; verified via ICJ website, ICRC IHL Database. This is an educational summary, not the judgment itself. Cite the reported version in professional or academic work.