Some technoweenie in a Belgian court has ruled that ISPs are responsible for the file sharing used by their customers... Out-law has some blurb about this, but the real chatter is on the NANOG list.
Yes, you've guessed it, someone (International Federation of the Phonographic Industry, RIAA, some arsehole...) whined about file sharing. Without really understanding how the internet works, the Belgians decided something must be done, and that file sharing should be blocked across an ISP's network.
Now, how exactly does this work? The thing that makes file sharing illegal or legal is the people involved, not the files or the mechanism for sharing them... A blanket ban on file sharing will not solve the problem since people will find other ways to share files, whether they are legally entitled to or not.