The federal judge who ruled last week that MP3.com broke copyright laws said the company does not just store already purchased CDs, but replays music on the Internet that it has copied without permission from recording companies.

U.S. District Judge Jed Rakoff made his comments in an opinion explaining last week's ruling that MP3.com violated copyright law with the creation of a database in which users can effectively store music and then access it via any computer connected to the Internet.The ruling, which sent shares of the online music-downloading company plummeting to an all-time low last week, stemmed from a lawsuit filed in January by the world's largest record labels, which said MP3.com's database of more than 80,000 albums infringed their copyrights. The service features software that lets computer users with an original copy of one of the recordings in the database to register that CD. It then allows the person to listen to that album over the Internet from any computer, without having to insert the original disc. The judge's ruling marked a key victory for the recording industry in its aggressive anti-piracy crusade launched partly in response to the success of MP3 technology. The MP3 format allows music to be downloaded from the Internet in small amounts of data. The compression makes it easy to store and copy music on personal computers.