SAN FRANCISCO, CA — A federal judge has issued an interim order blocking the sale of Real Networks’ RealDVD software. The software allows users to copy DVDs.At least, lawsuit insiders have reported that’s what happened inside U.S. District Judge Marilyn Hall Patel’s courtroom. The information can’t be confirmed because the judge slapped a gag order on the proceedings.

Patel is the same judge who presided over the Napster case that resulted in the former file-sharing giant revising its business model to prevent content piracy. The current case was brought against Real Networks by the Motion Picture Association of America.

Real Networks’ website vaguely alludes to the rumored temporary restraining order, but doesn’t spell it out: “Due to recent legal action taken by the Hollywood movie studios against us, RealDVD is temporarily unavailable.”

However, there are clues in documents recently filed with the court.

“Defendants have already caused significant irreparable harm to Real by prevailing upon this court to institute a temporary halt to sales of RealDVD since the evening of Friday, October 3, 2008,” a letter from Real Networks to Patel states. “The grant of a further TRO or preliminary injunction now will devastate Real’s ability to ever launch RealDVD successfully or to capitalize on its lead over competitors.”

The MPAA sued Real over what it claims is a violation of the Digital Millennium Copyright Act: The software allows users to circumvent built-in DVD copyright-protection mechanisms. The MPAA further claims Real is in violation of a contract with the DVD Copy Control Association, which granted the company a license to decrypt DVD security measures in order to develop a DVD player.

Real, which denies any wrongdoing, began distributing RealDVD September 30th.

Patel has scheduled a hearing for Tuesday and may decide then whether to make permanent the restraining order.