"Apparently intentionally, those restrictions reduce global market competition. They inhibit rights ordinarily acquired by Australian owners," said the court in its judgement.
Lawyers for Mr Stevens said yesterday the unanimous decision by the High Court would have "far-reaching implications for the manufacturers of computer games". One of the lawyers, Nathan Mattock, said it would be felt across the games industry.
"Computer game makers may have to change the way they have programmed their consoles," he said. "You can imagine the cost involved."
Mr Mattock said the decision would help bring prices down.
The Australian Competition and Consumer Commission had earlier aided Mr Stevens's case by arguing in the Federal Court that the games industry was unfairly using regional coding to set prices in different parts of the world.
Matthew Rimmer, a copyright law expert at the Australian National University, said the High Court had taken a narrow interpretation in deciding that Playstation's regional coding did not fit the description of protection technology within the copyright act. "They were concerned about the protection of copyright impacting on competition policy."
However, he said the decision would "cause a real difficulty for the Federal Government which had to undertake to change its legislation in this area as part of the US Free Trade Agreement".
The federal Attorney-General's office said the decision showed the act was effective in providing protection for copyright holders while allowing Australian consumers to use legitimately acquired products.
Sony declined to comment.