Non-intervention is a foundational principle of public international law that prohibits one state from coercively interfering in the internal or external affairs falling within the domaine réservé (reserved domain) of another sovereign state. It flows directly from the principle of sovereign equality codified in Article 2(1) of the UN Charter, and is reinforced by Article 2(7), which restrains even the United Nations itself from intervening in matters "essentially within the domestic jurisdiction of any state." The principle was given its fullest treaty-like elaboration in UN General Assembly Resolution 2625 (XXV) of 1970, the Declaration on Principles of International Law concerning Friendly Relations, and earlier in Resolution 2131 (XX) of 1965 on the Inadmissibility of Intervention. The International Court of Justice authoritatively confirmed its customary status in Nicaragua v. United States (1986), holding that the principle "forbids all States or groups of States to intervene directly or indirectly in internal or external affairs of other States."
The decisive legal test articulated in Nicaragua is coercion: a prohibited intervention "bears on matters in which each State is permitted, by the principle of State sovereignty, to decide freely" — such as choice of political, economic, social, and cultural system and the formulation of foreign policy — and uses methods of coercion to subvert that free choice. Mere criticism, diplomatic protest, or the severance of voluntary aid does not breach the rule; the supply of arms, funding, or organisation of armed bands against a government does. Non-intervention is distinct from, though overlapping with, the Article 2(4) prohibition on the threat or use of force: an intervention may be unlawful as coercive interference without rising to an armed attack. It is qualified by valid consent of the territorial state, by Chapter VII enforcement action authorised by the Security Council, and is contested at the margins by claimed exceptions such as humanitarian intervention and the Responsibility to Protect (R2P), adopted in paragraphs 138–139 of the 2005 World Summit Outcome.
Named instances dominate exam treatment: the US covert support for the Contras condemned in Nicaragua (1986); India's reliance on non-intervention rhetoric alongside its 1971 intervention in East Pakistan; NATO's 1999 Kosovo campaign (described as "illegal but legitimate"); and the 2011 Libya intervention under Resolution 1973. As of 2026 the principle is invoked acutely in debates over cyber-operations and election interference, where states like Russia and China stress non-intervention against Western "values diplomacy," while the contours of "coercion" in cyberspace remain unsettled in the UN GGE and Open-Ended Working Group processes.
For the exam, non-intervention recurs in the International Law / International Relations papers (UPSC GS-II and the Law optional; FSOT US foreign-policy section). Typical question angles ask candidates to distinguish non-intervention from non-use of force, to state the Nicaragua coercion test, to reconcile the principle with R2P and humanitarian intervention, and to evaluate its erosion through cyber and economic coercion. Cite Article 2(7), Resolution 2625, and Nicaragua (1986) for full marks.
Example
In Nicaragua v. United States (1986), the ICJ held that US training, arming and financing of the Contra rebels breached the customary principle of non-intervention in Nicaragua's internal affairs.
Frequently asked questions
Non-intervention bars coercive interference in another state's domestic jurisdiction, while Article 2(4) specifically prohibits the threat or use of force. An economic boycott or funding of opposition groups can violate non-intervention without amounting to an armed attack, so the former is broader but less severe than the latter.