What Is the Outer Space Treaty? Space's Constitution

Quick answer

The Outer Space Treaty of 1967 is the foundational law of space: no national appropriation of celestial bodies, no nuclear weapons in orbit, states responsible and liable for their space activities — including private ones. Over 110 nations are party, and all space law builds on it.

📘 Full definition✓ Reviewed 2026-09-07

The Outer Space Treaty (formally the Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space) entered into force in October 1967 and remains the constitution of space law. Its load-bearing articles: space is free for exploration and use by all states (Art. I); no part of it, Moon included, may be claimed by sovereignty or occupation (Art. II); no nuclear weapons or weapons of mass destruction in orbit or on celestial bodies, and no military bases on the Moon (Art. IV); states bear international responsibility for national space activities — expressly including those of private companies, which must be authorised and continuously supervised (Art. VI); launching states are liable for damage their objects cause (Art. VII, elaborated by the Liability Convention); and states retain jurisdiction over their registered objects (Art. VIII, elaborated by the Registration Convention). Drafted for two superpowers, its principles now govern an era of mega-constellations, lunar commerce and debris — stretched, debated, but unreplaced.

Signed

27 January 1967

In Force

10 October 1967

Parties

110+

Key Provisions

No WMDs, no sovereignty claims

Understanding Outer Space Treaty

The treaty family

Four further UN treaties elaborate the 1967 framework: the Rescue Agreement (1968) on aiding astronauts, the Liability Convention (1972) on damage claims, the Registration Convention (1975) on cataloguing objects, and the Moon Agreement (1984), which sought a common-heritage regime for lunar resources but attracted no major spacefaring party. Together with national law and soft-law instruments like the debris mitigation guidelines, they form the layered legal stack every mission flies under.

A 1967 text meeting 2026 problems

The treaty predates commercial constellations, orbital debris consciousness, satellite servicing and lunar business plans. Its answers arrive by interpretation: is a debris-generating ASAT test "harmful contamination"? Does supervising ten thousand private satellites strain Article VI? Can safety zones around lunar operations coexist with non-appropriation? The pressure has produced norms, accords and national statutes — but remarkably, no state has sought to abandon the foundation.

Frequently Asked Questions

Does the treaty ban all weapons in space? ▼

No — only nuclear and other weapons of mass destruction stationed in orbit or on celestial bodies. Conventional anti-satellite weapons, military satellites and ground-launched interceptors fall outside Article IV's ban, which is why ASAT tests are fought over as debris and norm questions rather than clear treaty violations.

Can companies own resources they extract in space? ▼

The treaty forbids national appropriation of territory but is silent on extracted resources. The US, Luxembourg, Japan and others have legislated that their companies may own what they mine; the Artemis Accords assert the same reading. It remains the treaty's most actively contested interpretive gap.

What makes Article VI so consequential? ▼

It erases any private loophole: a state answers internationally for its companies' space activities and must authorise and supervise them. Every national licensing regime — and thus every launch licence, debris rule and frequency condition a company faces — is Article VI cashed out.

Outer Space Treaty (1967)

Understanding Outer Space Treaty

The treaty family

A 1967 text meeting 2026 problems

Frequently Asked Questions

Sources & References