A chart illustrates data collected in the study, and shows the relationship between the percentage of states with graduated teen driving laws and the percentage of teens who drove after drinking themselves, or rode with a driver who had been drinking.
Credit Insurance Institute For Highway Safety
This chart illustrates the times at which teens are allowed to drive in different states.
New research out of Washington University suggests the answer is "yes" to our headline question - that laws restricting how late at night teens can drive or how many passengers they can have may also be keeping teens from driving drunk.
The study used data from 1999 to 2009 on teen drinking and driving in 45 states with graduated driving licensing laws.
Wash U. psychologist Patricia Cavazos-Rehg led the study. She says states adopted teen driving restrictions at different times, and that some states are stricter than others.