The U.S. Supreme Court rejected a challenge Monday from a telecommunications industry group against the city of Berkeley ordinance that requires cell phone retailers to provide radiation warnings at the point of sale.

The ordinance, which was passed by City Council in 2015, requires cell phone retailers to post or provide flyers with a safety message. The message warns consumers who carry cell phones connected to wireless networks on their bodies that the levels of radiofrequency emitted by the phone may exceed the Federal Communication Commission’s, or FCC’s, safe exposure guidelines.

The Cellular Telecommunications Industry Association, or CTIA, sued the city in 2015 to prevent the ordinance from taking effect, arguing that the ordinance violated retailers’ 1st Amendment right to free speech.

While a district court originally ruled in favor of CTIA, the ordinance was allowed to go into effect after the city changed some of the original warning message’s language.

This is the second time CTIA has appealed to the Supreme Court about the city’s ordinance. In 2018, the Supreme Court sent the case back to the U.S. Court of Appeals for the 9th Circuit, which originally ruled in favor of the city.

Ellie Marks, executive director of the California Brain Tumor Association, described the most recent ruling as a “big victory.”

“I started working on this cell phone ‘Right to Know’ with the Berkeley City Council in 2009 — it’s been a 10-year journey,” Marks said. “I’m thrilled that we had a victory. I think people should have access to this information so that they can make an informed decision (on) how they and their children can use (cell phones).”

According to Marks, the warning the ordinance requires retailers to post is the same information that the FCC already compels cell phone companies to provide to consumers.

Director of the Center for Family and Community Health at the UC Berkeley School of Public Health Joel Moskowitz, who has written extensively on this issue, said in an email that the Supreme Court decision sets a precedent for other cities that may be considering similar ordinances, especially as the telecommunications industry transitions to 5G technology.

“The Supreme Court’s refusal to hear this case for the second time sends a message to cities that it is okay to adopt laws like Berkeley’s cell phone ‘right to know’ ordinance to protect their residents’ health and safety,” Moskowitz said in the email. “With the deployment of 5G technology and 5G-enabled smartphones, it is imperative that everyone be educated about cell phone health risks.”

CTIA disputes the claim that cell phone use is linked to cancer, pointing out that the FCC’s guidelines say evidence of illness linked to cell phone technology is “ambiguous and unproven” and that “experimental research has been unable to reproduce” reported effects.

“We’re disappointed with the court’s decision, and we encourage consumers to listen to the FDA, the American Cancer Society, and the international scientific community when it comes to radiofrequency (RF) exposure,” said CTIA spokesperson Jilane Rodgers Petrie in an email.

A study published in 2018 by the National Toxicology Program, an interagency program within the Department of Health and Human Services, found “clear evidence of tumors in hearts of male rats” and “some evidence of tumors in the brains of male rats” exposed to high levels of radio frequencies used in 2G and 3G cellphones.

In a statement released by his office, Mayor Jesse Arreguín also described the court’s decision as a victory. In light of the court case’s resolution, other cities are expressing interest in establishing similar ordinances, according to the statement.

“This decision is a victory for our public health and safety,” Arreguín said in the statement. “I want to thank Professor Lawrence Lessig, our City Attorney’s Office, the California Brain Tumor Association, and those who have advocated for this Ordinance over the past four years.”

Contact Alexandra Stassinopoulos at [email protected] and follow her on Twitter at @AE_Stass.