San Francisco ? The wireless industry sued the city of San Francisco on Friday to stop a law that requires cell phone stores to post how much radio energy each model emits.

It’s the first law of that kind in the U.S. The industry trade group known as CTIA — The Wireless Association said the law will mislead consumers into thinking one phone might be safer than another on the basis of radiation measurements.

Studies have not conclusively found that cell phone radiation is a health risk. Research continues on brain tumors.

In its lawsuit filed in U.S. District Court in San Francisco, the industry group said the city is usurping the authority of the Federal Communications Commission, which sets limits for phone radiation.