Ignition Interlock Laws Help Stop Drunk Driving Before it Starts

ignition interlock deviceIt’s no secret that ignition interlock devices are an effective method to prevent repeat-offense drunk drivers. In fact, arrest rates are often reduced by 70% after interlock devices are installed. However, new research suggests that the mere threat of having to install a car breathalyzer after a first-time DUI offense may be enough to deter impaired drivers from getting behind the wheel of a car in the first place.

A new study from the Johns Hopkins Bloomberg School of Public Health revealed that states with mandatory ignition interlock device laws for first-time offenders had a 7% lower alcohol-related crash fatality rate than those states with only partial or court-decided interlock laws. In real numbers, that translates to 1,250 fewer deaths on the road due to impaired driving, per state, per year.

“These interlock laws are increasingly common, but they can still be controversial because they impose a pretty big imposition on people who have to install them,” said Beth McGinty, who co-authored the study at the Hopkins Center for Injury Research and Policy. “And until recently, we haven’t had good data on how they affected fatal crashes, which was the goal of the laws.”

The study analyzed over 30 years of crash data, comparing states before and after they mandated interlock laws, as well as between states with various regulations. Currently, 28 states require ignition interlock devices for anyone convicted of a DUI offense, while others only require them after repeat offenses or high-BAC incidents. Those with blanket policies saw a 7% reduction in alcohol-related crash fatalities after the rules were implemented, while those with only partial laws saw only a 2% reduction rate.

“This is the first solid research we have for advocates to say ‘no’ when a policymaker says, ‘Oh, my constituents aren’t going to like that mandatory law. Can’t we just do a partial law for repeat offenders?'” McGinty said. “The partial law is not nearly as effective.”

While interlock devices are a great way to reduce drunk driving after they’re installed, the fact that they might prevent offenses from happening in the first place is even better news, helping to make our roadways safer for all.

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