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Study: Strict Ignition Interlock Laws Linked to Fewer Drunk Driving Deaths

By Christopher Coble, Esq. on January 11, 2017 | Last updated on March 21, 2019

States have been steadily cracking down on drunk drivers, in part by instituting harsher punishments for first-time DUIs. One of those punishments is requiring drivers to install an ignition interlock device -- a sort of breathalyzer for your car that requires drives to provide a clean breath sample before starting the car.

According to researchers, these efforts might be paying off. A new Johns Hopkins study found that states that passed mandatory interlock ignition laws saw a seven percent decrease in fatal drunk driving accidents. The numbers would suggest that more of these laws are on the way, and they will be enforced more often after first-time DUIs.

Statute Statistics

"Until this study, we had no evidence on which type of interlock laws worked in terms of preventing alcohol-involved fatal crashes and whether one worked better than the other," said study co-author Beth McGinty. "Our study suggests that they are effective, and it's encouraging to see more and more states moving towards this evidence-based policy change."

The study, performed by Hopkins Center for Mental Health and Addiction Policy Research and published last week in the American Journal of Preventive Medicine, tracked alcohol-related traffic fatalities from 1982 to 2013, along with drunk driving statutes enacted over the same period. After controlling for other motor vehicle safety laws, the researchers found some 1,250 alcohol-related fatal crashes prevented in those states where ignition interlock penalties were enforced.

What Does It All Mean?

McGinty's research could demonstrate just how often drunk driving deaths are caused by repeat DUI offenders: with ignition interlocks preventing impaired drivers with prior DUI convictions from starting their cars, there are fewer fatalities. Or, as the Washington Post's Ashley Halsey III suggests, the laws may have a preventative impact: "Drunk drivers are less likely to get behind the wheel if they know a conviction will require them to blow into a breath-testing device every time they want to start their car."

The underlying data isn't too hard to understand -- if a drunk person can't drive, he or she won't cause an accident. What may be more difficult to grasp, though, is that if ignition interlocks are so effective at preventing fatal accidents, why don't all cars come equipped with them right out of the factory?

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