How to read the stack
International space governance is not a single rulebook but a layered system. At the top sit the UN General Assembly resolutions and the five core treaties adopted between 1967 and 1979, which are binding on states that have ratified them. Below the treaties sit non-binding “soft-law” instruments — guidelines, best practices, and political commitments — that fill the gaps where treaty text is silent or where rapid technical change has outpaced treaty negotiation. At the base, each state implements its international obligations through its own national licensing and supervision regime.
Tier-by-tier reference
Tier 1 — United Nations General Assembly (UNGA). Adopts resolutions that frame space norms and, when ready, opens treaties for signature. UNGA resolutions are recommendations, not binding law, but several have crystallized into accepted state practice.
Tier 2 — Committee on the Peaceful Uses of Outer Space (COPUOS). Established by UNGA Resolution 1472 (XIV) in 1959; works through a Legal Subcommittee and a Scientific and Technical Subcommittee. COPUOS is the primary forum where the five core treaties were drafted and where today’s soft-law guidelines are negotiated.
Tier 3 — The five core treaties (1967–1979). Together these instruments form the constitutional core of international space law:
- Outer Space Treaty (1967) — non-appropriation of celestial bodies, peaceful purposes, state responsibility for non-governmental activities (Article VI), state liability (Article VII).
- Rescue Agreement (1968) — return of astronauts and space objects.
- Liability Convention (1972) — absolute liability for damage caused on the surface of the Earth by a launching state’s space objects.
- Registration Convention (1976) — public registry of launches maintained by the UN Office for Outer Space Affairs (UNOOSA).
- Moon Agreement (1979) — common-heritage framework for the Moon and other celestial bodies; few signatories among major spacefaring states.
Tier 4 — Soft-law instruments. Non-binding but operationally influential.
- COPUOS Long-Term Sustainability of Outer Space Activities Guidelines (2019) — 21 voluntary guidelines on policy, safety of operations, space-debris mitigation, and capacity building.
- Inter-Agency Space Debris Coordination Committee (IADC) Space Debris Mitigation Guidelines — the technical baseline that most national debris-mitigation rules import or reference.
- Artemis Accords — U.S.-led set of principles for cooperative civil lunar exploration; signed by an expanding list of states.
Tier 5 — National implementation. Under Article VI of the Outer Space Treaty, each state is internationally responsible for the activities of its non-governmental entities and must “authorize and continually supervise” them. National licensing regimes (e.g., U.S. FAA, FCC, and NOAA authorizations) carry the actual operational burden.
Why this matters for students and practitioners
Most practical questions in space operations — debris-mitigation requirements, spectrum allocations, remote-sensing licensing, post-mission disposal — are answered at Tiers 4 and 5, not in the treaties themselves. Reading the stack from the top down explains the source of authority; reading it from the bottom up explains what an operator must actually do.
Primary sources
- United Nations Office for Outer Space Affairs (UNOOSA), “United Nations Treaties and Principles on Outer Space.” https://www.unoosa.org/oosa/en/ourwork/spacelaw/treaties.html
- Committee on the Peaceful Uses of Outer Space, Guidelines for the Long-term Sustainability of Outer Space Activities (A/74/20, Annex II, 2019). https://www.unoosa.org/oosa/oosadoc/data/documents/2019/a/a7420_0.html
- Inter-Agency Space Debris Coordination Committee, IADC Space Debris Mitigation Guidelines, Revision 3 (June 2021). https://www.iadc-home.org
- U.S. Department of State, “Artemis Accords.” https://www.state.gov/artemis-accords/
Accessed May 21, 2026.