For each specific ISP, the punishment plays out differently.
After some delays, the movie industry's home-brewed system to fight Internet pirates has finally arrived, and depending on their internet service provider, pirates may not have all that much to fear. In light of the government's inability to pass legislation like SOPA and PIPA the Motion Picture Associate of America and Recording Industry Association of America got together with the country's major ISPs—Verizon, AT&T, Cablevision, Time Warner Cable, and Comcast—to put in place their own system to crack down on illegal downloads. The result is a six-strike system that varies depending on the ISP, according to a report by The Wall Street Journal. In general, the system involves sending offenders "progressively assertive" warnings, after each offense.
The violation is determined by the content owner, which is where the MPAA and RIAA come in. Or, if the download occurs from an IP address associated with pirating, that can trigger a warning notice, too. Beyond that, however, for each specific ISP the punishment plays out differently.