It works like this: users accused by Rightscorp are found via IP addresses appearing in BitTorrent download swarms. If ISPs agree to forward Rightscorp's notices—and an increasing number of them are doing so—the users get notices that they could be liable for $150,000 in damages. Unless, that is, they click on a provided link and agree to settle their case at a low, low price. Typically, it's $20 per song infringed.