If someone's downloading your copyrighted work illegally, suing them is no easy task. The only public facing information that identifies you to the internet are just numbers in the form of IP addresses. To actually get the name of the person doing the illegal downloading, intellectual property owners have to request or subpoena the information from Internet Service Providers like Verizon or Time Warner. But earlier this week, Comcast, the largest cable provider in the country, refused to honor court ordered subpoenas of customer identifying information.

In an interview we did in 2010 with Nate Anderson of the website Ars Technica, he told us how ISPs go about identifying and suing alleged infringers.

BOB GARFIELD: So how does this law firm go about identifying potential culprits? 

 NATE ANDERSON: They have partnered with a firm called Guardalay. What they do is monitor bit torrent downloads. They can see which internet protocol addresses are sharing parts of these files, and then these cases are filed, 2,000, 4,000, in some cases even 5,000 anonymous users at a time. And the lawyers ask the courts to help them turn these IP addresses into real people's names and addresses. 

BOB GARFIELD: And the internet service providers have to comply? 

NATE ANDERSON: If the subpoenas are valid, the ISPs would turn over the information of their subscriber who is using that address at that particular date and time. Time Warner Cable has been objecting to the subpoenas on the grounds that they're unduly burdensome, and they are trying to get the courts to either quash these subpoenas or cut them back radically. 

As the blog VentureBeat points out, this move is likely less motivated by an interest in protecting consumers than it is in trying to avoid the cost and hassle of participating in these cases. But it's still a major blow to companies that would try to sue because their work is being shared on the internet, and a major victory for internet privacy advocates.