The lawsuit filed last week by music publishers BMG and Round Hill against Cox Communications could be the next battle in the major media companies’ long-term campaign to turn Internet service providers into copyright police. BMG and Round Hill are asking a federal court to declare that ISPs like Cox must terminate their customers’ accounts whenever the publishers’ agent—a company called Rightscorp—says so. Because Cox didn’t immediately kick subscribers off of its service after Rightscorp accused those subscribers of copyright inf