Before I proceed with this essay. let me emphasize that nothing I say here is to be construed as legal advice. If you’re planning on claiming an asteroid or something, consult a lawyer.
The fancy Latin term for unclaimed land is terra nullius. There are a few such places still here on Earth – Antarctica, parts of the international sea, and an area between Egypt and Sudan known as Bir Tawil. Essentially all of space remains unclaimed. Traditionally, land that is terra nullius may be claimed by occupation.
In 1967, several countries signed the Outer Space Treaty (or, more formally, Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, Including the Moon and Other Celestial Bodies, 1967 U.S.T. Lexis 613, TIAS 6347.) This treaty bans countries from claiming celestial bodies for themselves. Specifically, Article II states: “Outer space, including the moon and other celestial bodies, is not subject to national appropriation by claim of sovereignty, by means of use or occupation, or by any other means.” As of 2011, 101 countries have signed and ratified this treaty, including every major country.
This leaves few legal possibilities for countries to claim celestial bodies. One of the countries that has not signed this treaty could theoretically claim such land, but none of them are currently in a position to attempt spaceflight. More likely, countries that have signed and ratified this treaty might choose to ignore it. This is a problem generally in international law, and stems in part from the inability of the United Nations to enforce their own laws. If a major signatory of this treaty, like the United States or China, decided to start claiming the moon or asteroids there is precious little that the U.N. could do about it.
Perhaps more likely, the treaty might also be repealed as spaceflight becomes more capable. The U.N. (or a body acting similarly in the future) might decide that the solar system is not claimable, and perhaps other habitable planets are not claimable by a particular country, but asteroids and other planets, being so abundant, might well claimable through occupation, adverse possession, use, or some other traditional mechanism. After all, if there are hundreds or thousands of asteroids, does it really matter if some percentage of them are claimed? Mightn’t the ability to claim celestial bodies drive space exploration and mining?
Another possibility is that by the time claiming celestial bodies becomes practical the countries of the Earth will meld into a single government. Presumably a single body claiming a celestial body for all of Earth comports with the intent and words of the treaty. Of course, many other changes would come with such a unification so any commentary about the effects of a single government on a multi-country treaty is speculative at best.
This essay was first published in John’s blog, BoydFuturist, HERE