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 infringement, BMG and Round Hill say that Cox should pay potentially millions of dollars in penalties.

BMG and Round Hill are basing their suit on the Digital Millennium Copyright Act’s safe harbor provision. That law gives Internet intermediaries, including ISPs, protection against many copyright lawsuits if the ISPs follow some procedures laid out in the law. One of the requirements is that ISPs must have a policy for, in “appropriate circumstances,” terminating “subscribers and account holders” who are “repeat infringers.” The music publishers claim that whenever Rightscorp accuses an ISP subscriber of being a “repeat infringer,” Cox must terminate that user or (1) lose the safe harbor protection; and (2) be liable for massive copyright penalties.

There are two obvious flaws in this theory. First, the safe harbor doesn’t require ISPs to terminate users on a mere accusation of infringement—or even repeated accusations. The law calls for termination only for repeat infringers, and only in appropriate circumstances. Rightscorp’s “because I said so” letters to ISPs aren’t enough, because Rightscorp doesn’t give any evidence of copyright infringement or explain how they detected it—the company just insists that it happened. The courts haven’t said exactly what a “repeat infringer policy” has to include, but we know it requires more than bald accusations. It’s frightening to contemplate a world where mere accusations of infringement are enough to get an Internet account and everyone who depends on it thrown off of the Internet.

Second, even if Cox loses safe harbor protections, it's not at all clear that it needs them. Cox itself doesn’t help subscribers infringe copyrights any more than Ford or Toyota help bank robbers by building getaway cars. Absent some additional facts (like actively encouraging subscribers to download content illegally), Cox and other ISPs can’t be held liable for simply transmitting data to and from the Internet for its customers, even if some customers download music or movies illegally.

There is a yet more fundamental problem, though. An ISP only knows who its subscriber is—the name on the Internet bill—not who was using an Internet connection at a given time. Many people share an Internet connection within a household, or run open wi-fi as a way of being neighborly. Just as an ISP isn’t responsible for copyright infringement by users for simply moving their bits, a home Internet subscriber shouldn't be held responsible for infringement they didn’t know about or assist. A given IP address is not a "repeat infringer," though a given user may be.

Major media companies, including music publishers, have long sought to turn ISPs (along with major Internet sites, search engines, and payment processors) into copyright enforcers, removing people and materials from the Internet whenever the media giants ask for it. The notorious SOPA and PIPA bills, the failed lawsuits against YouTube and Veoh, and the “Six Strikes” copyright surveillance system are all part of this strategy. The BMG/Round Hill lawsuit looks like the latest move in this campaign.