Jon Lech Johansen, nicknamed "DVD Jon" by the local media, 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 had appealed the ruling.

The MPAA has accused Johansen, 20, 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 in order to develop a DVD player for the computer operating system Linux, not to copy DVD movies, and 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.

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.

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.

The programme, which he posted on an Internet site, enables users to circumvent anti-piracy software for Apple's iTunes site and download music for free, instead of paying the normal 99-cent charge per song.

SPACE.WIRE