It's illegal to download anything copyrighted. However, downloading torrents is not illegal so long you're downloading something that's not copyrighted (or something that's copylefted). The use of torrents cannot be prohibited for the reason that not all torrents are illegal.
I was just wondering how any site for example btjunkie is allowed to provide the link to copyrighted material. I'm not downloading anything anymore. I did a few songs and one video. but now that I realize how much trouble you can get into it's not worth it. plus these people go through a lot of trouble to make these movies/songs etc etc.
Coming from a university- P2P or Torrent programs are used quite a bit on campuses for legitimate reasons. Companys do track illegal downloads and sharing through the IP's, and send notices to the service providers. Usually at first it is just a warning, but it can escalate really easily.