Siding with several of Hollywood's largest movie studios, a US federal judge has barred 321 Studios from manufacturing, distributing, or otherwise trafficking in software that allows users to copy DVDs.

After hearing the case last May, US District Court Judge Susan Illston on Friday ruled that 321 Studios' DVD copying software is illegal and ordered the St. Louis-based company to stop selling the products in US stores within seven days.

321 Studios will appeal and is seeking a stay of the ruling pending appeal, the vendor says in a statement.

Civil liberties group The Electronic Frontier Foundation, which has supported 321 Studios and others charged under the Digital Millennium Copyright Act, calls Illston's ruling a setback to consumers' rights.

321 Studios' software enables users to copy DVD movies onto recordable DVDs or standard CD-R disks. The software circumvents the encryption technology used on the discs to prevent copying, called Contents Scrambling System (CSS). 321 Studios uses a freely available decryption technology called DeCSS to evade CSS.

The company markets several versions of the software. DVD X Copy Express, released in May 2003 copies only the movie and soundtrack, omitting menus, multiple language tracks, and special features now packaged with most movies released on DVD.

DVD X Copy Gold, released in June 2003, lets users copy most DVDs within an hour and record all features of an original CD or compress a DVD-9 to a DVD-5, fitting each backup copy onto a single DVD disk. DVD Copy Plus, copies a DVD to a CD-R/W. The top of the range product, DVD X Copy Platinum, includes some customisation options.

321 Studios positions its products as back-up utilities.

If it can't get a stay on the order to stop offering its products during the appeal process, 321 Studios plans to continue selling its software, but without the DeCSS technology, according to the company.

Buyers will have to download DeCSS software, called a "ripper," from the internet if they want to copy protected DVDs, according to a 321 Studios spokesperson.

"Our software will not be able to back up CSS encrypted movies without the ripper," she said. "But rippers are freely available on the internet and our product will work seamlessly with those rippers."

321 Studios filed suit against several motion picture companies in 2002 as a preemptive strike. A countersuit followed.

Friday's ruling followed a motion filed by MGM Studios, Tristar Pictures, Columbia Pictures, Time Warner Entertainment, Disney, Universal City Studios, and The Saul Zaentz Company.