Its becoming an epidemic. These copyright troll lawyers are threatening to sue everyone from grandmothers to the blind.
The companies make a log of IPs from a bittorrent client, usually a porno, and they subpoena the ISPs to hand over the infos. Once these scum bags get a hold of your info, they harass you and try to extort $3500-$5000 USDs for. They threaten to sue but almost never due. Instead they intend to embarrass the John Does to fork over the money. Fortunately, some are fighting back.
Some of their underhanded tricks is file in multiple courts until a judge rules in their favor.
They even invent titles like "Teen Anal Sl*ts" and just to threaten people.
More on these copyright trolls can be found here.