system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5:  Current US piracy law

When and how can torrent client users etc. be prosecuted or tracked down by the government?
gpt
Agencies hired by the RIAA/MPAA/whoever else will go into popular torrents and download them like a normal user. Doing so gives them a list of all of the seeds and leechers in their client, like any other user has. An IP address alone however, is like having someone's street address but not their name. So they petition the ISP that governs that IP and say "Hey we have a warrent give us the information relating to this IP address" and they have to comply. You might get a Cease and Desist letter or something related as well. These groups make their money because people will hurry to settle instead of trying to fight them in court, because they have millions of dollars in legal advice. 

Note: the government is not the one suing people. It's companies trying to protect their investments.