How do you stop a charging porn thief?

Take away his credit card.

That’s what a Beverly Hills pornographer is aiming to do in filing a copyright and trademark suit against Visa International Service Association and MasterCard International Inc.

Perfect 10 Inc., which publishes an adult magazine and operates an adult Web site, says hundreds of Web site operators around the world are selling its trademarked images. While Perfect 10 has sued many of these outfits, its biggest beef is with the credit card companies that process the infringers’ transactions. The porn company says that without the support of these financial institutions, infringers wouldn’t be able to steal their stuff.

The credit card companies say requiring them to enforce the property rights of a third party is unheard of and would have ramifications for all service providers.

“It’s an attempt to enforce copyright and trademark liability far beyond any published case ever,” said Mark Jansen, a partner at Townsend and Townsend and Crew who is representing Visa.

“If the court were to impose liability in that context and make companies subject to contributory liability on the basis of aiding and abetting infringement, that would extend across commerce,” he added. “It would convert financial institutions into judges, juries and policemen.”

Perfect 10’s attorney, Howard King, of Los Angeles’ King, Holmes, Paterno & Berliner, agrees that the suit is treading new territory.