Big ISPs like AT&T, Verizon, Comcast, Cablevision, and Time Warner Cable have agreed on a set of policies to crack down on copyright infringers. It doesn't involve any scanning on the part of the networks themselves. What would happen is that a copyright holder would scan the IP addresses online of people grabbing, say, a pirated movie. The copyright holder would then alert the ISP associated with that address and the ISP has now agreed to alert the user that he or she is doing something wrong. But even after six warnings, it's not clear what actually happens. It's kind of a "stop or I'll tell you to stop again" kind of system. It's likely much more toothless than what Hollywood or the recording industry would like but it's the ISPs way of washing their hands of a lot of the issues related to piracy.