The chairman of space history at the National Air and Space Museum has said that “[t]he idea that a private investor can put together the funds to develop rockets capable of a lunar mission is extremely speculative, verging on fantasy.” And so far, he’s been right.
But there are a fair few investors out there who want to prove him wrong, and one day, inevitably, if we ever want to truly expand into space rather than merely treat the cosmos as a glorified science lab, it’s going to take private commercial initiative to do it. So what happens if it’s a private corporate entity that first encounters intelligent extraterrestrial life?
Public international law (as opposed to conflicts of law) governs, in theory, only the relationships between sovereign states, not the actions of private individuals. The body of space law recognizes this, and rather than imposing restrictions on private spacecraft, it instead imposes obligations on states to regulate the space activities of non-governmental bodies under their jurisdiction.
As an initial matter, it is certainly legal under international law for non-government bodies to engage in space travel. The USSR, during negotiations over the Outer Space Treaty (“OST”), had originally wanted to ban all private space flight, but the U.S. refused to agree to this. However, whether private individuals can obtain property rights in space is a separate, more difficult, question. Although appropriations of resources by states is prohibited, this prohibition was not explicitly extended to cover non-governmental corporations. Many commentators have made the case that private ownership in space is therefore allowed, and have explained how ownership can exist even outside of state jurisdiction by reference to civil systems [PDF]:
The relationship between property and sovereignty differs under common law and civil law systems. The common law theory of title has its roots in feudal law. Under this theory the Crown holds the ultimate title to all lands, and the proprietary rights of the subject are explained in terms of vassalage. Civil law, on the other hand, is derived from Roman law, which distinguishes between property and sovereignty. Under this theory, it is possible for property to exist in the absence of sovereignty.
So for now I’m going to assume that, yes, private property in space is possible, based on a discovery-and-exploitation regime that grants rights to those who first make use of a new territory. (This will be partially in following with the property-ownership aspects of the Larkin Decision, from the Federation Court, holding that “the real owners [of a celestial body] were the flesh-and-blood men who had maintained the occupation.” See Robert A. Heinlein, Stranger in a Strange Land (1961).)