Some automakers are already selling kits to make it easy to voice activate a call, and various technologies will eventually be so widespread that such a law might not be needed, Fabris said.

Fabris said he expects many states to follow California's lead. "California is often put forward as a leader with legislation," he said, noting that Palm is active in Europe where such laws have long been in place.

The CTIA, a Washington, D.C.-based industry group comprising cellular technology manufacturers and carriers, opposes such legislation, according to its Web site. Various safety officials and lawmakers "have all concurred that such legislation is ineffective, most likely has a negligible impact on safety and obscures the greater issue of driver distraction," the group says on its site. "In addition, law enforcement officers in all 50 states already have the ability to cite drivers for reckless or inattentive driving."

The CTIA cited government statistics and research studies to argue that "the focus on wireless phone use while driving is well off point.... Every state that currently reports crash data (California, Florida, Michigan, Minnesota, Oklahoma, Pennsylvania and Tennessee) shows that wireless phone use is a factor in less than 1 percent of accidents. Furthermore, a report published in 2004 by the AEI-Brookings Joint Center for Regulatory Studies, finds wireless phone bans to have no significant impact on accidents."

CTIA officials could not be reached for comment Friday.