As California joins five other states in requiring drivers to use hands-free devices when talking on cellphones, an increasing body of research suggests the legislation will accomplish little.
The risk doesn't stem from whether one or both hands are on the wheel, the research suggests. It's whether the driver's mind is somewhere else.
The biggest danger is "cognitive capture" -- or being blind to driving cues because one is absorbed in conversations, especially emotional ones.
"There's a common misperception that hands-free phones are safer when the research clearly suggests that they they're both equally risky," said Arthur Goodwin, a researcher at the University of North Carolina Highway Safety Research Center.
California motorists will be required to use a hands-free device to talk on a cellphone starting July 1 under a new traffic safety law. Such laws are already in effect in New York, New Jersey, Connecticut, Utah, Washington state and the District of Columbia.
Hands-free laws have come to be seen as the most politically feasible way to address the dangers of driver distraction because of cellphone use.
Gov. Arnold Schwarzenegger sought to reassure drivers that they need not hang up their phones when he spoke at a signing ceremony for the California law in 2006. "You don't have to stop talking on your cellphone, but use a headset or use a speaker system, and you will be fine."
If hands-free is the path of least resistance, it was still a long, hard slog for Sen. Joe Simitian, the Palo Alto Democrat who sponsored the bill. Simitian tried but failed to win passage for five years before breaking through. He said he persisted because he was sure the law would save lives.
"There isn't a study in the world that says you're safer driving with a cellphone clutched to your ear than when you are driving with both hands on the wheel," he said.
But Goodwin and other scientists say that hands-free laws could actually make things worse by encouraging drivers to make more or longer calls.
Indeed, federal highway safety officials drafted a letter from then-Transportation Secretary Norman Y. Mineta to the nation's governors in 2003 to warn against laws like California's that allow hands-free calling. For reasons never fully explained, the letter was neither signed by Mineta nor sent. According to the bluntly worded letter, obtained by The Times, "overwhelmingly, research worldwide indicates that both hand-held and hands-free phones increase the risk of a crash."
