Retailers in Berkeley, Calif. must warn customers about possible harm from radiation from cellphones, according to a court ruling yesterday.

The landmark decision could open the door to similar warnings at retailers across the U.S.

CTIA, the wireless trade association, whose slogan is “Everything Wireless,” had fought Berkeley on this issue for more than seven years. It has not indicated it is giving up its battle against warnings in stores.

The U.S. Court of Appeals for the Ninth Circuit denied a petition by CTIA for a rehearing of the issue.

Lawrence LessigLawrence Lessig

It said CTIA “had little likelihood of success on its First Amendment claim that the disclosure compelled by the Berkeley ordinance was unconstitutional.”

Harvard Law professor Lawrence Lessig, who argued for the city in the case, said, “We are hopeful that this will bring an end to this case, and the City of Berkeley will again be free to govern its citizens as its citizens demand.”

CTIA, represented by Theodore Olson of Gibson, Dunn & Crutcher, said, “The courts have acknowledged that Berkeley has presented no evidence that cell phones cause harmful effects. We will continue to assert that the First Amendment prohibits the government from forcing private companies to promote misleading and inaccurate opinions.”