Outer Space Treaty, 1967

The Outer Space Treaty, 1967 establishes the basic legal framework for the exploration and use of outer space, including the Moon and other celestial bodies. It combines freedom of exploration with non-appropriation, state responsibility, and specific restrictions on military activities. It does not, however, completely demilitarise outer space.

Freedom of use and non-appropriation

Under Article I, outer space is free for exploration and use by all states, with free access to all areas of celestial bodies. Under Article II, outer space, the Moon, and other celestial bodies cannot be nationally appropriated through sovereignty claims, use, occupation, or any other means.

• A state cannot annex celestial territory, and prolonged occupation or settlement cannot mature into territorial title.
• States may conduct scientific investigations and place equipment without acquiring sovereignty over the underlying territory.

Restrictions on military activities

The treaty imposes different rules for outer space generally and for celestial bodies. Under Article IV, states cannot place in Earth orbit objects carrying nuclear weapons or other weapons of mass destruction, install such weapons on celestial bodies, or station them in outer space in any other manner.

• The Moon and other celestial bodies must be used exclusively for peaceful purposes.
• Military bases, installations and fortifications, weapon testing of any kind, and military manoeuvres are prohibited on celestial bodies.
• Military personnel may be used for scientific research or other peaceful purposes, and equipment necessary for peaceful exploration may also be used.
• The treaty does not expressly prohibit conventional weapons in Earth orbit or every military activity in outer space outside celestial bodies. Activities must nevertheless comply with international law, including the UN Charter, under Article III.

Responsibility, jurisdiction and unresolved issues

The treaty makes states accountable for national space activities while preserving jurisdiction over registered space objects without creating territorial sovereignty.

• Under Article VI, states bear international responsibility for activities of governmental and non-governmental entities; private activities require authorization and continuing supervision.
• Under Article VIII, the registry state retains jurisdiction and control over its space objects and personnel, but not sovereignty over surrounding celestial territory.
• Under Article IX, states must show due regard for others, avoid harmful contamination, and undertake consultations where an activity may cause potentially harmful interference.
• The treaty does not expressly determine whether extracted space resources may become property, so their legal treatment remains debated.