The Recording Industry Association of America sued San Mateo-based Napster in December alleging copyright infringement and related state law violations. The association accused Napster of encouraging users of the company’s software and computer servers to trade copyrighted music online without permission.

Napster officials said the company’s service is legal because it does not directly provide the copyrighted music only the means to get it.

The company, which faces a separate lawsuit by the heavy metal band Metallica, also sought to define itself as an Internet service provider to limit its liability under the Digital Millennium Copyright Act.

However, U.S. District Judge Marilyn Hall Patel refused to grant Napster’s request that the lawsuit be dismissed, ruling Friday that it was not entitled to ‘safe harbor” under the Digital Millennium Copyright Act because it “does not transmit, route or provide connections for allegedly infringing material through its system.”

The “safe harbor” provision was crafted to protect Internet service providers such America Online, AT&T Worldnet and Earthlink from illegal actions committed by their users.

“Although the Napster server conveys address information to establish a connection between the requesting and host users, the connection itself occurs through the Internet,” Patel wrote.

The RIAA applauded Patel’s ruling.

“This hearing was Napster’s attempt to escape responsibility for aiding and abetting wide scale piracy and, not surprisingly, they lost,” RIAA president Hilary Rosen said Monday.

Napster lawyer Laurence Pulgram said Patel’s opinion would simply “move the case ahead” and that the court would still need to determine whether Napster users were violating the law if they made copies of songs for their own personal use.

Some colleges have blocked students from accessing Napster because their heavy usage overloaded school computer networks.

Users of the MP3 format for storing music on computer hard drives can use Napster’s software to catalog their selections and make those music files available for others to download over the Internet.