Thats part of the problem with P2P though, is the way they do it (as best as I understand it), the actual stuff that is being pirated is hosted on hundreds of computers world wide with that many owners. Naturally this means their are dozens of countries whose Copyright Law apply to them individually, and its impractical and for all intents in purposes impossible to stop it all technologically or legally. All the torrent sites do is keep track of what is where, being nothing more then directories that organize the chaos. If for example the Pirate Bay the Internets most popular torrent site gets taken down (which it will eventually) I have no doubt it will simply send the data to another organization who will maintain it.
Truth be told if they wanted to make it impossible to stop and strike a killing blow it could simply make the program which runs it Open Source, in which case ANYONE could take it and create clone sites. Before you know it their would be more torrent sites created then be shut down because the process of setting one up would be comparatively simple as all they would need to do is buy server space in a third world country with loose laws and upload the code to the server, buy a domain name, and presto instant site. Its a real mess and one I don't see getting solved anytime soon...