The Moon Agreement: Why Almost No One Ratified It

Of the five United Nations treaties on outer space, four are part of the furniture. The Outer Space Treaty has 118 parties. The Rescue Agreement, the Liability Convention and the Registration Convention have between 77 and 100 each. Space lawyers cite them every week.

The fifth has 17. It was the last of the UN space treaties to be negotiated, it took most of the 1970s to agree, and the General Assembly adopted it in December 1979. Then almost every country that could actually reach the Moon declined to join it. That is an unusual fate for a treaty, and the reasons say a lot about how international space law is made, and how it stops being made.

This is the story of the Agreement Governing the Activities of States on the Moon and Other Celestial Bodies, better known as the Moon Agreement.

What the Moon Agreement actually says

Most of the text is uncontroversial. Read on its own, much of it looks like a more detailed version of the Outer Space Treaty.

It applies to the Moon and to every other celestial body in the solar system except Earth, so it is not really about the Moon alone. It says the Moon shall be used exclusively for peaceful purposes, and it bans the threat or use of force there, weapons of mass destruction in lunar orbit or on the surface, military bases and weapons testing. It asks states to avoid disrupting the lunar environment. It requires them to tell the UN Secretary-General about their missions and about anything they find that could endanger human life. It gives states the right to collect samples and, under Article 6(2), to use lunar minerals “in quantities appropriate for the support of their missions.”

None of that stopped anyone from signing. The problem was one article.

Article 11 and the two words that sank it

Article 11, paragraph 1 says that “the Moon and its natural resources are the common heritage of mankind.” The rest of the article builds on that sentence.

Paragraph 3 says that neither the surface nor the subsurface, “nor any part thereof or natural resources in place,” can become the property of any state, organisation, company or person. Paragraph 5 commits the parties to “establish an international regime, including appropriate procedures, to govern the exploitation of the natural resources of the Moon as such exploitation is about to become feasible.” Paragraph 7 lists what that regime is for, ending with “an equitable sharing by all States Parties in the benefits derived from those resources,” with special consideration for developing countries and for the countries that helped pay for exploration.

You can read the full text in the UN’s compilation of the space treaties. It is worth reading slowly, because almost every word was fought over.

To understand why the phrase “common heritage of mankind” frightened governments in 1979, you have to look at what else was happening that year. The same idea sat at the centre of the law of the sea negotiations then under way, which produced UNCLOS in 1982. Part XI of that convention declared the deep seabed and its minerals the common heritage of mankind and created an International Seabed Authority with its own mining arm, powers to license miners, and provisions for transferring technology. The United States refused to sign UNCLOS largely because of Part XI. The industrialised states only came round after a separate agreement in 1994 rewrote the seabed regime to suit them.

So when Washington’s negotiators saw “common heritage of mankind” in a treaty about the Moon, they did not read it as a vague aspiration. They read it as the first step towards a lunar version of the Seabed Authority, with an international body deciding who could mine, on what terms, and who would share the profits.

The American campaign against it

The United States took part in negotiating the text. It never signed.

The opposition in Washington was unusually public for a treaty debate. The L-5 Society, a group of space settlement enthusiasts inspired by Gerard O’Neill’s ideas about colonies in orbit, campaigned hard against ratification, with the lawyer Leigh Ratiner arguing that the treaty was hostile to private enterprise and private property. Parts of the aerospace and mining industries agreed. The core argument was simple. If no one could own resources in place, and a future international regime would decide how resources were exploited and shared, then no company would invest in lunar mining until that regime existed. Critics called it a moratorium in all but name.

Supporters answered that the treaty banned ownership of resources in place, not of resources once extracted, and that the regime was meant to be negotiated only when mining was close to feasible. That reading is defensible. But in 1980 there was no way to know what the regime would look like, and the UNCLOS experience suggested it would not be friendly to the countries doing the mining. The Senate was never asked to consent. The treaty was simply left alone.

The Soviet Union, which had tabled the first draft of a Moon treaty in 1971, did not sign the final text either, and neither did China. With the two space powers of the day and the rising third one all outside, the treaty had lost the only parties whose behaviour it could realistically constrain.

In force, but not for the people it was written for

The Moon Agreement needed five ratifications. It got them slowly, and it entered into force on 11 July 1984. A treaty in force binds its parties and nobody else. It does not bind the United States, Russia or China, and nothing in state practice since 1984 suggests its distinctive rules on resources have become customary international law binding everyone.

Article 18 required the General Assembly to consider a review ten years later. When 1994 came, the Assembly took no further action. Nobody wanted to reopen a text that the major powers were ignoring anyway.

In 2008, seven of the parties (Austria, Belgium, Chile, Mexico, the Netherlands, Pakistan and the Philippines) tried a different approach. They presented a joint statement on the benefits of adherence to the Legal Subcommittee of the UN Committee on the Peaceful Uses of Outer Space. It argued that the common heritage principle did not exclude any particular model of exploitation, public or private, and did not forbid commercial treatment, so long as exploitation was compatible with the treaty’s framework. In plain terms, the parties were saying: this treaty is more business-friendly than you think. Very few new parties were persuaded.

How the treaty came apart

The decisive change came when lunar and asteroid resources stopped being hypothetical and states started legislating for them.

In 2015 the US Congress passed the Commercial Space Launch Competitiveness Act, which says that a US citizen who recovers an asteroid or space resource is entitled to possess, own, transport, use and sell it. That provision now sits in chapter 513 of Title 51 of the US Code. Luxembourg passed its own space resources law in 2017, the United Arab Emirates in 2019 and Japan in 2021.

In April 2020 the White House went further. Executive Order 13914 stated that the United States “does not view” outer space as a global commons, and that it “does not consider the Moon Agreement to be an effective or necessary instrument.” It directed the State Department to object to any attempt by other states to treat the agreement as customary international law.

Six months later the first eight nations signed the Artemis Accords. Section 10 of the Accords says that extracting space resources does not in itself amount to national appropriation under Article II of the Outer Space Treaty. It is the opposite starting point from Article 11 of the Moon Agreement. We looked at that clash in detail in our explainer on who owns the Moon.

Then the parties started crossing over. Australia, a long-standing Moon Agreement party, was a founding signatory of the Accords in October 2020 and has said the two instruments are in harmony. Saudi Arabia signed the Accords in July 2022 and, six months later, on 5 January 2023, gave notice that it was withdrawing from the Moon Agreement. The withdrawal took effect on 5 January 2024. It was the first time any state had left any of the five UN space treaties. Writing at the time, two researchers at McGill’s Institute of Air and Space Law warned that the agreement was “hanging by a thread.”

No other party has followed Saudi Arabia out. But the crossover has continued. By September 2026 the Accords had 75 signatories. Twelve of the 17 remaining Moon Agreement parties are among them: Armenia, Australia, Austria, Belgium, Chile, Mexico, Morocco, the Netherlands, Peru, the Philippines, Türkiye and Uruguay. Morocco signed in April and Türkiye at the end of August. The five parties that have not signed are Kazakhstan, Kuwait, Lebanon, Pakistan and Venezuela. Of the four states that signed the Moon Agreement but never ratified it, France, India and Romania have all signed the Accords.

Can a state be in both?

This is the question the twelve have to answer, and it is more interesting than it first looks.

The case for compatibility runs like this. The Artemis Accords are a political commitment, not a treaty. Article 11(3) of the Moon Agreement bans ownership of “natural resources in place,” which leaves room to argue that resources, once extracted, can be owned. Article 6(2) already allows states to use lunar minerals to support their missions. And the international regime in Article 11(5) only has to be established when exploitation “is about to become feasible,” which it arguably still is not. On that reading, nothing in the Accords requires a party to breach the Moon Agreement today.

The case against is that the two instruments start from opposite premises. The Moon Agreement treats lunar resources as a shared inheritance whose exploitation should be governed collectively and whose benefits should be shared. The Accords treat extraction as something states and their companies can do under national law, coordinated through bilateral commitments and safety zones. A party that has undertaken to establish an international regime, and then signs up to an approach built to avoid one, is at the very least sending mixed signals. Saudi Arabia evidently concluded it could not hold both positions.

My own view is that the compatibility argument is legally available and politically thin. Twelve parties can hold it for now because no one is mining the Moon yet. When someone does, the Article 11(5) obligation will be very hard to square with national licences issued under the Accords model.

Why it still matters

It would be easy to write the Moon Agreement off. Legally, for the states that will actually mine the Moon, it is already off.

But the treaty’s central questions were never silly. Who gets to extract lunar ice first? Does the first operator to arrive get priority indefinitely? Should states that cannot reach the Moon share in any of the value? Those questions are now on the table at the UN working group on the legal aspects of space resource activities, set up under COPUOS’s Legal Subcommittee. It has been producing drafts of recommended principles, most recently in December 2025, and its workplan aims to finalise them in 2027. The drafts are non-binding, and the language of common heritage is nowhere near them. But the arguments over benefit-sharing, transparency and priority of access are the same arguments the Moon Agreement’s drafters were having in the 1970s.

The Moon Agreement failed because it tried to settle the answer before anyone had a working mine to argue over, and because it borrowed a concept that the industrialised world had just learned to fear on the seabed. It did not fail because the questions were wrong. Whoever writes the rules that actually govern lunar mining will end up answering the same questions.

Anuj KumarEditor-in-Chief

Anuj Kumar is the founder of Legal Desire Media and publishes Fashion Law Journal and Space Law Journal.

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