According to an article on cnet.com, the manner in which Comcast is filtering BitTorrent traffic may, in fact, be criminal. Comcast is sending forged RST (reset) packets to the end-user, which may qualify as impersonating with the intent to profit. (Criminal Impersonation in the 2nd Degree). Whether or not this plays out in court remains to be seen.
Comcast’s Torrent Filtering: Criminal Acts?