Restrictive licensing laws have helped reduce teen drunk driving and fatal crashes by 30 percent.
"We were interested in determining whether these laws were making it less likely for teens to engage in drinking and driving behaviors," Cavazos-Rehg says.
The researchers gathered drinking and driving information from more than 220,000 16-17-year olds who were surveyed between 1999 and 2009, when state laws that restrict teen driving were strengthened.
They then compared the anonymous surveys with state laws and found that teens living in states with the strictest laws also were least likely to drink and drive or to ride in a car with a driver who had been drinking.
Cavazos-Rehg can't say precisely what is causing the decrease in risky drinking and driving behaviors, but she believes nighttime restrictions that limit how late a young driver can be behind the wheel may be key.
"That's getting teens to go home earlier, which means they may not have the opportunity to go to parties where there are opportunities to drink," she says. "We haven't looked at that closely yet, but that's the next step."
The other aspects that may influence teens' behavior include stiff penalties, like suspension of a driver's license, for violations, Cavazos-Rehg says. Many laws also require more experience and education behind the wheel before a license is granted than was required in past years. And in most states that have enacted these laws, teens don't receive full driving privileges until they are 18 or even older.