I read a Science Illustrated/Illustrert Vitenskap* article on Extra-Terrestrial law some years ago, and I've been interested in "Interstellar law" for some time.
Basically, everything a certain altitude over Earth is no-man's land. This was "automatically" estabilished when probes and satellites started to orbit Earth and no one protested (weaker, poorer countries did, hoping to make a profit by selling permission to use their airspace, but they were ignored). You can't own land beyond the Earth, you can't enforce laws there, and you can't claim ground there.
Certain Web sites† and firms do sell property on the Moon and on other planets, but according to laws and treaties, you can't own pieces of Mars, the Moon, Venus, or Uranus, even if you've been there (Neil Armstrong and Buzz Aldrin could not claim the landing site of Apollo 11 for the USA). So to put it simply: Don't buy a Lunar crater. Not only do nations have no obligation to recognize your claim (yes, the USA can build a Martian colony on top of "your" lot), and second, the people you buy the lot from are no more entitled to it than you are, meaning that you've got no reason to not simply ineffectively claim a crater on the Moon yourself instead of buying one from a firm that's ineffectively claimed it. It works the same way as the Antarctica treaties: National and private claims to Antarctica are not recognized by the treaty countries, so while a lot of countries, from Norway to Britain and Russia, have claimed large pieces of the continent for themselves (take a Norwegian atlas and look up Queen Maud's Land, and it'll have "Norway" in fine print below it;)).
So the reason Planetary Investments can claim that
Mr. D. Hope has been in the business of selling Lunar Property for over 23 years. In all this time, and more than 2 million customers later (and increasing rapidly), we have never had a single unsatisfied customer
is that no one yet has told these customers that their claim is void and set a mine or hotel or research centre or strip club on top of the "satisfied customer's" property. These people are "satisfied" because the consequences of their actions haven't arisen (yet), like I can be "satisfied" with my life vest that doesn't work if I'm never going to go near a body of water with it on, or with my virus program on a computer that'll never be exposed to a single virus.
But the point of the article was that in the future, if/when mining and colonization of space becomes a reality (please do not start do discuss whether this can or should happen in this thread: Start a separate thread should you be interested), laws and regulations are required. Otherwise, you can simply walk into a rival mining colony and steal whatever they've extracted, for example.
Discuss (as if I need to tell you).
Foot notes
* Science Illustrated (
www.illvit.com) (site in Norwegian)
†Google Search (
http://www.google.no/search?hl=no&q=land+for+sale+moon&btnG=S%C3%B8k&meta=) [and] Planetary Investments (
http://www.planetaryinvestments.com/)