It's legal in 41 states for drivers to use hand-held cell phones, and a leading highway safety organization recommends keeping it that way for now.
The Governors Highway Safety Association, or GHSA, urges states to hold off on banning the practice until more research is done to gauge the effectiveness of such laws.
"The problem is the research is conflicting on the issue," says Barbara Harsha, executive director of the group, which advises states on traffic safety. "We don't know if hand-held bans are effective, and we don't know if they actually make the problem worse."
The Insurance Institute for Highway Safety said last year it found no reduction in crashes after hand-held cellphones were banned in California, Connecticut, New York and Washington, D.C.
The National Safety Council says hand-held bans don't go far enough. "We think there is enough research to enact total bans, hand-held and hands-free," says David Teater, senior director of transportation initiatives at the NSC. "And there's no evidence that hands-free devices provide any safety impact."
At the National Highway Traffic Safety Administration, the federal agency that tracks road deaths, "we feel strongly there is robust evidence on the dangers of distracted driving," says Lynda Tran, NHTSA's director of communications.
The GHSA made its recommendation after reviewing research on distracted driving since 2000 - about 350 studies, Harsha says.
That review followed questions from governors and state legislators who are trying to navigate this still-unfolding aspect of road safety.
Transportation Secretary Ray LaHood has made curbing distracted driving a signature issue.
Some corporations restrict the use of cellphones by employees while in company vehicles. And among some federal workers, the use of the devices while driving is limited.
The greatest momentum has come from lawmakers at the state level: Nine states and the District of Columbia ban hand-held cellphones for all drivers.
Texting while driving is illegal in 34 states and the District of Columbia. Twelve states banned it in 2009, 11 did so last year, and two have so far this year.
No states ban all cellphone use by all drivers.
According to the Department of Transportation, 5,474 people died and another 448,000 were hurt in crashes involving all forms of distracted driving in 2009.
Explore further: Four questions about missing Malaysian plane answered