Jon Lech Johansen, known in cyberspace by his nickname "DVD Jon", pleaded not guilty to the charges brought by the Motion Picture Association of America (MPAA).

The court had already acquitted him in January but the prosecutor appealed the ruling.

The MPAA, which groups together studios such as Disney, Universal and Warner Brothers, has accused 20-year-old Johansen of creating, at age 15, the DeCSS computer program that decrypts DVDs, and distributing it on the Internet.

In his defense, Johansen has argued that he developed DeCSS with two friends in order to develop a DVD player for the computer operating system Linux for his own use, not to copy DVD movies.

He has said he could not be held responsible if people used the program to make pirated copies of DVDs.

"DeCSS opens the door to the mass distribution of illegal DVD copies," prosecutor Inger Marie Sunde said Tuesday.

"We appealed the acquittal because we felt that there were procedural errors and the verdict was not based on the heart of the issue," Sunde said.

Hollywood has a keen interest in winning the case, as it struggles to maintain control over the use of its products. The verdict could create a legal precedent in Norway and elsewhere.

Johansen, who describes himself as "a self-taught information technology student", said he should be allowed to do what he likes with a product he paid for.

"His aim is to defend the principle of consumer rights," Johansen's lawyer, Halvor Manshaus, said.

The trial is likely to last for two weeks, with a verdict expected in January.

Johansen faces up to two years in prison if found guilty.

"This has been hard on him. After all, he was only 15 when this all started. Police have used enormous resources against him during these past four years," his father Per Johansen told Norwegian public radio NRK on Tuesday.

DVD Jon has achieved cult-figure status among young websurfers, and last month landed another coup by cracking Apple Computer's online music site iTunes encryption code.

That program, which he posted on an Internet site, enables users to circumvent anti-piracy software for Apple's iTunes site and download music bought on iTunes on to their hard drive in its original format.

The user can then do as he wants with the music. The iTunes site normally allows users who buy a song for 99 cents apiece to burn it onto a CD only once, and listen to it on a maximum of three different computers.

Using DVD Jon's program, users can however copy a song and redistribute it as many times as they like.

Johansen has said that, as in the case with DVDs, his aim is to remove the obstacles that still face consumers even after they have made a purchase.

SPACE.WIRE