[link|http://www.theregister.co.uk/2005/06/27/p2p_goes_down/|Supremes down P2P software makers in unanimous decision]

...The ruling means that developers of P2P software can be held liable for their users' actions and that the software makers must work to prevent the distribution of copyrighted material. Two lower courts had already ruled that P2P software showed enough non-infringing uses for it to be protected under the well-known 1984 Sony ruling that permitted the sale of the VCR. The Supreme Court, however, disagreed with the lower courts, saying that they took too broad an interpretation on Sony and that the P2P firms made little to no effort to curb illegal file-trading.