Hands-free cell phone devices offer no advantage over hand-held devices.
That's the conclusion of a survey of studies conducted by the National Highway Traffic Safety Administration, first published in 2002.
Specifically, the study found "degradations in driver behavior" and "changes in risk-taking" in drivers using cell phones. It concluded this occured among cell phone-using drivers whether they were talking hands-free or not.
From the report: "...there are negligible differences in safety relevant behavior and performance between using hand-held and hands-free communications devices while driving from the standpoint of cognitive distraction."
The report, which is more than 250 pages long, looked at scores of reports and scientific studies in drawing its conclusions.
But NHTSA withheld the report, and killed a proposal to follow it up with it's own long-term study. This was at a time when many states were outlawing the use of handhelds by drivers, but allowing hands-free devices. Critics say the NHTSA was fearful of alienating members of Congress who'd directed the agency to stick to collecting safety data and not lobby for changes in state traffic laws.
This summer, two consumer groups obtained the report through the Freedom of Information Act, and passed the document along to The New York Times, which published a story about it in July.
See the NHTSA report below.