I read somewhere most government space agencies such as NASA, USAF, etc., already have rules mandating that upper stages and satellites at end-of-mission are de-orbited, or least a good-faith attempt has to be made. No one can blame you if you try and the hardware fails you. Commercial space operators may or may not behind the curve on this. I suspect that they have to follow some rules as well. It seems to me that the problem isn't U.S., Russia, or ESA these days so much as it's the new players in the space game, such as China. They are still in the "cold war stage" of space development and don't mind making lots of junk in exchange for prestige and political gain. Given time and some diplomacy, they'll see the benefits of reducing junk and come along, too. This isn't a show-stopping problem as long as we're thinking about it now.