From this article:

"Under the 1967 Outer Space Treaty, nations retain 'jurisdiction and control' over their spacecraft even when they are inoperable, meaning that a salvage operator wouldn't be able to take title or claim an award for recovering a defunct craft as is done on earth. Space lawyers (yes, there are space lawyers) have been arguing for years that the proliferation of space junk makes some sort of salvage law necessary, but up to now there has been little progress. The technology for recovering defunct satellites is there, though cleaning up smaller debris fragments would be much, much harder. That's a reason to try to get a handle on the problem sooner, rather than later. A space salvage law might even give a shot in the arm to commercial space efforts, by providing yet another money-making option."