Science-- there's something for everyone

Thursday, November 8, 2012

Graduated driver license decals mean fewer crashes


Over the past few years, all U.S. states have passed graduated driver licensing (GDL) laws. These laws restrict teenaged drivers during their first months or years of having a license. For example, teens may not be allowed to carry passengers or to drive alone late at night. While this may seem like a good idea, it’s very difficult to enforce these laws. Police can’t tell whether a driver is under the jurisdiction of the GDL laws unless they stop him and examine his license. Some other countries with similar laws also require novice drivers to display decals on their cars. Police in these locations can clearly see if a car with a novice driver sticker is carrying a load of teenagers.

Would having a GDL decal affect crash rates within the U.S.? I’m glad you asked. It turns out that, thanks to New Jersey having implemented the first GDL decal law in the nation, we now have some data on the subject. Allison Curry from the Center for Injury Research and Prevention, The Children’s Hospital of Philadelphia, and her colleagues compared the number of citations and crashes given to teens both before and after the law was passed.

a New Jersey license plate.

The red decal required by the New Jersey law.

The New Jersey law requires all drivers under age 21 to display decals on the front and back license plates of any car they are driving. Citations increased by about 14% after the law went into effect on May 1, 2010. This isn’t surprising, since the decals made it much easier for police to pick out obvious violators. More importantly, there was a 9% decrease in the number of car crashes involving teen drivers after the GDL decal requirement became law. Police may be watching teen drivers more carefully or teens may only perceive that they’re being watched, but in any case, the law seems to be contributing to a safer driving environment for young people.

The decal law is not without controversy. Many teens and their parents would like to see it repealed, not least because they say it could allow predators to target young drivers. Those fears might change once information on the decrease in crash rates is disseminated among the public. In that case, perhaps other states will pass GDL decal laws as well.


Allison Curry, Melissa Pfeiffer, Russell Localio, & Dennis Durbin (2012). Graduated Driver Licensing Decal Law Effect on Young Probationary Drivers American Journal of Preventive Medicine.