Torrents are 100% legal, if they are linked to NON-Copyrighted materials.
If they are linked to copyrighted content, then using the torrent to download it IS illegal.
Torrents are a means to an end, if your end is copyrighted warez, moviez or muzic than you are breaking the law in most countries, Definantly in the U.S.
See Link below concerning Downloading and sharing copyrighted music, movies, and software.
Legal alternatives to illegal file sharing
Hope this helps