Stopping peer to peer is a very difficult task. You'll either need to stop all the peers or their underlying network.
I suppose stopping the internet or making computers illegal would be extremely unpopular for any kind of government/authority!
Any legislation which allows outside forces (i.e., the government and all its pets) to spy on what you do on your computer would likely bring an end to, well, almost anything, but Bitcoin included. I don't think they're ever going to stop introducing new bills about it, until they've lobbied their way into your hard drive
Last I heard was CISPA, but there's bound to be plenty more under different guises all aiming for the same thing. VPN is pretty easy to get nowadays tho...
