NASA file

An artist's conception shows a mining operation on a near-Earth asteroid.

If private ventures start building settlements and factories on the moon, on Mars or on asteroids, someone may also have to build a new legal framework for the exploitation of those extraterrestrial resources. Experts on both sides of the debate over property rights on other worlds agree that the current rules may not cover the challenges that could crop up on other worlds.

But should that take the form of legislation on a nation-by-nation basis, or a new international code of conduct? For now, the question is theoretical. But this month's debate over measures such as the 45-year-old Outer Space Treaty and the proposed Space Settlement Prize Act may mark one small step toward a giant leap in off-world commerce.

Earlier this week, we discussed the idea of using a perceived "loophole" in the Outer Space Treaty that could allow the United States to recognize the property rights of private parties on other worlds. Since then, I've gotten in touch with Tanja Masson-Zwaan, the president of the International Institute of Space Law, and now I've heard the other side of the argument.

Masson-Zwaan told me trying to get around the 1967 treaty is "not the solution."

"Things have to be agreed on an international level," she said. "I don't think that the treaty has any kind of 'loophole.'"

The idea behind the Space Settlement Prize Act is that the Outer Space Treaty bars its signatories, including the United States, from asserting sovereignty over other worlds, but may not bar them from recognizing claims made by private parties. The act's backers note that a follow-on treaty, drawn up in 1979 and known as the Moon Treaty, specifically bans private property claims — and note that the United States is not a party to that particular pact.

Wouldn't that imply that the United States still has a free hand on private property claims? Masson-Zwaan says no. She says the private-property angle is addressed by the Outer Space Treaty, and merely reiterated in the later Moon Treaty. "It's often so in treaties," she said.

The key to her argument is that Article 2 of the 1967 treaty holds nations responsible for the extraterrestrial activities of their citizens. And it's not just her arguing that. This is the view of other legal experts, including TechFreedom's James Dunstan. (Masson-Zwaan said Dunstan's comments were "quite well worded.") What's more, it's been the stated view of the U.S. government. In 2003, a State Department official cited Article 2 in turning back a claim for parking and storage fees relating to NASA's NEAR Shoemaker spacecraft on the asteroid Eros.

A later ruling in federal court rejected the claim on different grounds, saying that the claimant failed to show any property interest in Eros. Would the outcome have been different if someone landed a robotic probe on Eros, and then commanded it to put down stakes and build a homestead? What if you had actual human homesteaders working and living on Eros? Should there be a law to recognize the settlers as property owners?

"If America would make such a law, then any country would do the same," Masson-Zwaan said. And that could lead to the kind of interplanetary discord the Outer Space Treaty was designed to avoid. She pointed to statements issued by her institute in 2004 and in 2009 to back up her point.

Masson-Zwaan acknowledges that the current treaty is not perfect. "More rules are needed," she said, "but I am also of the opinion that you do not need to create property rights." She points to the example of the Law of the Sea Treaty, which set up procedures for deep-sea mining licenses. (The Competitive Enterprise Institute, which commissioned this month's white paper on the Space Settlement Prize Act, has called the Law of the Sea Treaty "a bad deal for America.")

Right now, the outer-space property debate is a theoretical blue-sky extension of the globalism-vs.-libertarianism debate that runs through so many issues here on Earth. But if private ventures start putting rovers on the moon, or start sending mining machines to near-Earth asteroids, the debate could get much less theoretical. Feel free to re-read Monday's item on the outer-space "loophole," and then register your opinion in the poll above and/or the comment space below.

More about space settlement:

• Could lunar real estate spark a future war?
• Colonies on the moon? It's not a loony idea
• Will China take over the moon?
• Russia wants to build moon colonies

Alan Boyle is msnbc.com's science editor. Connect with the Cosmic Logcommunity by "liking" the log's Facebook page, following @b0yle on Twitter or adding Cosmic Log's Google+ page to your circle. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for other worlds.