The war on illegal sharing of copyrighted content via P2P networks took a sharp turn today, when the US Supreme Court ruled that peer-to-peer (P2P) file-sharing services could be held responsible in the event of their software being used to swap content such as movies and music illegally. In the past, all the creators of software such as Kazaa and Bittorrent had to do was claim that their software had legitimate, legal uses (which it does) to get off and place the burden of blame onto users themselves. Now this may change, forcing the creators of such software to adopt anti-piracy technologies just to stay on the right side of the law.

"We hold that one who distributes a device with the object of promoting its use to infringe copyright, as shown by clear expression or other affirmative steps taken to foster infringement, is liable for the resulting acts of infringement," Justice David Souter wrote in the majority opinion.