[Shuttle Shucker]

You can find the Outer Space Treaty and others here:

http://www.unoosa.org/oosa/index.html

Article II of the 1967 Outer Space Treaty of the United Nations (ratified by around 100 member countries) states that:

“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.”

Where does it say that private appropriation is banned, though?

[RightWhale]

private appropriation is banned

Court decision. It's over.

[NonZeroSum]

Where does it say that private appropriation is banned, though?

It doesn't. That's just RightWhale's mistaken interpretation. Smarter people than him, who actually understand space law, know that the OST doesn't ban it, and you're entitled to keep and sell resources that you acquire off planet. All the OST does is not allow declarations of national sovereignty.

The Moon Treaty is more problematic, but the US didn't sign on to it, so we're not bound by it.