One would assume that orbital space is a public good, usable by any nation that can get there.
And so, to avoid conflict, impact, landgrabbing, piracy, and the like, there is some supra national body with whom one, when wishing to launch into this space, negoiates? There are existing treaties dating back to the forties that restrict certain activities and allow others, but are they still valid and/or being observed?
After all, just lobbing stuff up there because you can seems a somewhat risky idea... and of course, while territorial claims might be extended vertically to infinity, there is no nation that can keep an orbit over their territory at all times. While a satellite might be a very small target in a very big space, even a speck of paint coming at you at orbital velocities (say, an equatorial orbit intersecting a polar one) can ruin your whole day.
So - can anyone tell me who this agency is?