Study: Ignition Interlocks Save Lives Even Before They’re Installed

A national road safety trend just got a boost from public health research. It was already known that ignition interlocks – devices which prevent a vehicle from starting if the driver has been drinking – are a proven measure to prevent drunk drivers from re-offending. Now a new ignition interlock study by the Johns Hopkins Bloomberg School of Public Health has found that states that mandate the devices for all drunk driving offenders, including first-time DUI offenders, have fewer alcohol-related road deaths.

Currently 28 states require the devices for all offenders. The Johns Hopkins study found that traffic fatalities declined 7 percent in states that mandated ignition interlocks for first-time drunken-driving offenders. The drop was bigger in states that required the devices for all offenders than others which only employed them for repeat offenders.

Ignition Interlock Study - fatalities decline 7 percentThe ignition interlock study, published in the American Journal of Preventive Medicine, tracked ignition interlock laws from 1982 to 2013, and assessed the effects of the laws.

The conclusion of the ignition interlock study is compelling: ignition interlock laws reduce alcohol-involved fatal crashes.

The reasons are twofold. Obviously, offenders who have the device installed will not reoffend. But the prospect of having the device installed is also a deterrent to those who might consider drinking and driving. So the devices are working to save lives even before they are installed.

That conclusion is news because of the 30,000 or so fatal crashes that occur each year in the US, a third of those involve alcohol. Ignition interlocks are the only measure that actually prevents a drunk driver from taking to the road. Fines and imprisonment have a place in the judicial landscape. Assessment and treatment are also vital, and interlocks should be a part of that too. But only interlock devices actually prevent drunk driving itself.

Also Needed: Better Interlock Compliance

The results that the Johns Hopkins study records were achieved under conditions that are far from ideal. While some states are enthusiastic about ensuring that all convicted drunk drivers comply with interlock laws, others allow offenders to slip through the cracks. News reports often feature crashes caused by drivers who should have had an interlock installed. If all states did a good job ensuring compliance, the number of lives saved would be even greater.

The Case for All-Offender Ignition Interlock Laws

While there is no shortage of documentation on the effectiveness of ignition interlocks as a preventive for impaired driving, the Johns Hopkins ignition interlock study is important because it makes the case for all-offender laws. Some legislators consider ignition interlocks too strict for first-time offenders, but the numbers tell the story: requiring ignition interlocks for all drunk driving offenders saves lives. If your state doesn’t have require ignition interlocks for all DUI offenses, it’s time to contact your legislator. Lives in your state are on the line.