One of the four men convicted in The Pirate Bay trial is seeking to have his guilty verdict thrown out after learning that the judge in the trial is a member of two pro-copyright groups, including one whose membership includes entertainment industry representatives who argued in the case.

Stockholm district court judge, Tomas Norstrm told a Swedish newspaper that his previously-undisclosed entanglements with the copyright groups did not constitute a conflict of interest.

The groups include the Swedish Association of Copyright, a discussion forum. Henrik Pontn of the Swedish Anti-Piracy Bureau, Monique Wadsted, a motion picture industry lawyer, and Peter Danowsky from the recording industry's IFPI are members of the organizations, and were largely responsible for pressing the case against The Pirate Bay before the judge.

Norstrm also sits on the board of the Swedish Association for the Protection of Industrial Property, and the Internet Infrastructure Foundation, which oversees the dot-se country code and advises on domain name disputes. Monique Wadsted is one of his colleagues at the foundation.

The judge's links to the groups were reported by Swedish National Radio. Peter Althin, the lawyer who represents Pirate Bay spokesperson Peter Sunde, announced Thursday that he plans to demand a retrial.

“The Court of Appeal will decide if the district court decision should be set aside and the case revisited," Althin said on Thursday to the site The Local.

Last Friday Norstrm and three lay judges found Sunde and three other men guilty of contributory copyright infringement, sentenced them to a year in prison, and ordered them to pay damages of 30 million kronor ($3.6 million) to entertainment companies.

“It wasn't appropriate for him to take on this case," says Eric Bylander, senior lecturer in procedure law at Gothenburg University. “There are several circumstances which individually don't constitute partiality, but that put together can form a quite different picture. It's also a matter of what signal this sends to the citizens. Anyone who, on reasonable grounds, can be appear biased in a case should not judge that case."

But Bylander says it's a toss-up as to whether the appeals court will find the conflict serious enough to throw out the verdict. “I don't think the trial will be declared a mistrial, but it's definitely a close call," he says.