In a lawsuit filed in the US District Court for the Northern District of California, the CTIA - a trade group representing leading mobile operators like Apple, AT&T, Verizon and Motorola – has alleged that San Francisco’s radiation ordinance is an unlawful interference with the US Federal Communications Commission (FCC)’s authority over mobile phones.

The last-month-passed San Francisco law, which the CTIA is trying to block, makes it mandatory for stores to disclose the Specific Absorption Rate (SAR) for the handsets they sell.

SAR is essentially a measure of mobile phone radiation; for which the FCC has set for handsets being sold in the country.

The San Francisco radiation law, aiming at apprising the consumers about the body absorption rates of certain handsets, comes at a time when scientists are debating whether mobile phone users face an increased risk of cancer.

According to the arguments put forth by the CTIA, the San Francisco ordinance is confusing as well as misleading for the consumers, who may think that some handsets are safer than the others.

Noting that “the FCC has determined that all wireless phones legally sold in the United States are ‘safe,’ CTIA spokesman John Walls said in a news release: “CTIA’s objection to the ordinance is that displaying a phone's SAR value at the point-of-sale suggests to the consumer that there is a meaningful safety distinction between FCC-compliant devices with different SAR levels.”