A federal judge has barred RealNetworks from selling its DVD-copying software, ruling that the technology violates Hollywood studios' copyrights and the licensing agreement RealNetworks has with the studios' copyright-protection group.

U.S. District Judge Marilyn Hall Patel issued the preliminary injunction against RealNetworks on Tuesday in San Francisco. The ruling prevents RealNetworks from selling its RealDVD software and any future products using the technology until its legality is determined in a trial.

The Motion Picture Association of America sued RealNetworks in November 2008. The DVD Copy Control Association, which licenses Hollywood-sanctioned copyright-protection technology, later joined the suit, claiming RealNetworks violated its DVD CCA license. RealNetworks builds on the anti-piracy technology for the security in RealDVD.

Patel's decision means RealNetworks is prohibited from selling its software for copying movie DVDs to computer hardware. Although RealDVD prevents content from being distributed, Patel decided the software still was in violation of the DVD CCA license, which prohibits any copying without the permission of copyright holders. In addition, Patel ruled that RealDVD violates the Digital Millenium Copyright Act.

"RealDVD makes a permanent copy of copyrighted DVD content and by doing so breaches its CSS (content scramble system) License Agreement with DVD CCA and circumvents a technological measure that effectively controls access to or copying of the studios' copyrighted content on DVDs," Patel's 57-page decision said.

RealNetworks said in a statement that it was "disappointed" with the ruling, but said a decision whether to appeal was pending. "We have just received the judge's detailed ruling and are reviewing it," the company said. "After we have done so fully, we'll determine our course of action and will have more to say at that time."