U.S. Judge Decides Against Madster

The music industry Wednesday won a preliminary injunction against Madster, an Internet file-swapping service that record labels allege is used by millions to trade pirated songs.

The order by Chief Judge Marvin Aspen of the U.S. District Court in Chicago is the latest in a series of legal victories for the Recording Industry Assn. of America, a group representing more than two dozen major record labels and media companies.

Aspen said that the RIAA proved Madster users engaged in copyright infringement and that Madster executives knew or should have known of the infringement. “Defendants manage to do everything but actually steal the music off the store shelf and hand it to ... users,” Aspen wrote.

“This unequivocal ruling today underscores that companies and individuals will not be permitted to build a business on music they do not own,” RIAA Chief Executive Hilary Rosen said.

Madster, founded in 1998, has 5 million to 10 million users, founder Johnny Deep said. Originally known as Aimster, the Albany, N.Y., company operates a free instant-messaging service that lets users swap files over the Internet.

Deep said his company is not capable of monitoring the encrypted messages that go through the Madster service.

“Every message on our service goes through an envelope so we never see what’s in those messages,” Deep said. “How does the post office prevent bootleg CDs from being mailed in plain envelopes? That’s our problem.”

In his ruling, Aspen ordered the RIAA to propose the wording for a final injunction. The order mirrors the legal path traveled by Napster, a controversial file-sharing service that has shut down.

When Napster complained of the difficulty of monitoring its members’ files, the judge in that case refused to allow the service to continue.