On Tuesday, the United States Court of Appeals for the Ninth Circuit heard arguments for and against nonprofit organization CTIA ­— The Wireless Association’s appeal of a U.S. district judge’s decision to allow a disputed Berkeley ordinance to pass.

The ordinance, which requires cellphone providers to post radiofrequency warnings in their stores, was originally unanimously passed by Berkeley City Council in May 2015. CTIA, which represents the wireless communications industry, sued the city of Berkeley in June 2015, claiming the ordinance violated CTIA members’ First Amendment rights.

Last September, U.S. District Judge Edward Chen granted Berkeley the right to pass a revised version of the ordinance and allowed it to pass after the revised language was approved. The ordinance went into effect in January.

“The ‘right to know’ (ordinance) simply takes info that is already available and makes it more visible to the consumer,”  said Councilmember Kriss Worthington, who sponsored the ordinance with Councilmember Max Anderson.

CTIA appealed Chen’s decision to deny an injunction that would have blocked implementation of the ordinance, according to Lawrence Lessig, a professor of constitutional law who is representing the city on a volunteer basis throughout its legal proceedings with CTIA.

“This is an issue I’m interested in, not so much because of cellphones, but because I am worried about the way the First Amendment is being perverted to enable corporations to block regulations,” Lessig said, adding that he also helped draft the original ordinance.

CTIA Senior Vice President and General Counsel Tom Power said in a statement that the ordinance “dramatically weakens First Amendment protections.”

Theodore Olson, an attorney representing CTIA, said during the hearing that the ordinance will mislead consumers because it warns against radiofrequency risks despite the Federal Communications Commission, or FCC, determining that the use of cellphones is safe.

“The FCC and other health and medical experts agree that the overwhelming scientific evidence refutes Berkeley’s ill-informed and misleading mandatory warnings about cell phones,” Power said in an email.

But Ellen Marks, executive director of the California Brain Tumor Association, or CABTA, said that, according to the FCC, cell phones are only safe if kept a certain distance away from the body.

The ordinance has not significantly hindered business, said Justin Kresanko, assistant manager at Downtown Berkeley’s MetroPCS, adding that he approves of the advisory notice to inform any customers who were previously unaware of the possible risks.

Marks, one of the advocates for the “right to know” ordinance, said it is imperative for citizens to make informed choices about their lives. Her organization’s goal is to prevent brain tumors and inform citizens that cell phone radiation causes health risks.

“We are not trying to hurt the industry or telling people not to use cellphones, we just want to build precaution,” Marks said.