An Oslo court has cleared Jon Lech Johanson, otherwise known as DVD Jon, of any wrongdoing after he distributed software for cracking DVDs.

In a ruling that could have a major impact on European Union copyright law, the court accepted Johanson's defence that he had developed the software, called DeCSS, to watch a legitimately purchased DVD on his Linux PC.

CSS (Content Scrambling System) is the encryption software which ensures that DVDs are protected and stops users skipping past messages like the FBI warning.

It was already possible to copy DVDs before DeCSS, but the process and media required were more expensive than the DVDs themselves.

Norweigan newspaper Aftenposten reported the court as stating: "The court finds that someone who buys a DVD film that has been legally produced has legal access to the film. Something else would apply if the film had been an illegal copy."

The 19 year-old was facing a potential two-year prison sentence after the Motion Picture Association of America made a complaint to the Norwegian authorities.

Johanson's lawyer alleged that the Association had originally requested that the boy and his father should both be arrested.

Prosecutors were asking for a 90-day suspended sentence, claiming that they were more concerned with winning the trial in principle than punishing the accused.

Johanson distributed the first software that could break the encryption built into DVDs when he was just 15.

He is co-founder of a group called the Masters of Reverse Engineering. When a German member of the group figured out a way to crack CSS, Johanson put a link to the software on his website.

Although the software has now been superseded, it spread widely and has been used in the piracy of DVD content.