The record companies' lawyers now have a green light to try to shut down the file-swapping services.

Will any of these approaches be enough to quell the musical thirst of the millions who, at the moment, get their music from free file-swapping services?

According to court documents, recording industry investigators in April 2004 came across an account with Kazaa, the Internet-based file-swapping service, that contained 1,322 music files.

And other file-swapping services have shut down.

You just can't share them through free file-swapping services like Kazaa.

Napster users were unable to access the file-swapping service for much of the weekend and yesterday while the company worked to transform itself into a fee-based business.

But the industry fears losing control of its products to the next generation of unlicensed file-swapping services, as data-compression technology and transmission speeds improve.

It has often been likened to Napster, which was shut down by a federal court ruling in 2001 as an illegal file-swapping service.

Songs arrived on file-swapping services as soon as people could record them from radio and digitize them.

Most recently, he said, predators have been trading pornography via file-swapping services once used just to trade music.