Insurance Org. Study: Ignition Interlocks Prevent Fatal Crashes

Data Shows Fewer Road Deaths When All DUI Offenders Use Ignition Interlocks

A new study by the Insurance Institute for Highway Safety has found that ignition interlocks –car breathalyzer devices which prevent a vehicle from starting if the driver has been drinking – work to save lives. The institute found that requiring the devices for all DUI offenders reduced the number of impaired drivers in fatal crashes by 16 percent compared with jurisdictions that have no interlock requirement.


The key finding is that the devices work best when required of all DUI offenders. Currently 31 states require ignition interlocks for all drunk drivers whose blood alcohol concentration (BAC) is at or over the legal limit of .08 percent. Other states only require them for repeat offenses, or offenses in which the BAC is much higher than .08 percent. Some states have no real interlock requirements, leaving it to a judge’s discretion.

According to the data in the study, the number of impaired drivers in fatal crashes drops more the stricter the ignition interlock requirement: 3 percent when they are required for repeat offenders only, 8 percent when repeat offenders and high-BAC first offenders use the device, and 16 percent when all DUI offenders are required to use interlocks. Having all states move to all-0ffender interlock laws would save hundreds of lives in just the first year.

Here’s the money quote:

The current study shows that the laws are especially effective at preventing fatal crashes among drivers with a history of DWI – a population of drivers at high risk for recidivism and crash involvement.As such, jurisdictions that do not currently have all-offender alcohol ignition interlock laws could expect large reductions in impaired driving crash deaths if they do adopt these laws.

Overwhelming Evidence: Ignition Interlock Work

ignition-interlock-breath-testThe study by IIHS, an independent, nonprofit scientific and educational organization, is hardly the first to make the case for ignition interlocks. Last July the National Safety Council issued a report urging states to adopt ignition interlock laws. The National Academies of Sciences, Engineering and Medicine said much the same thing in their report this January. Mothers Against Drunk Driving (MADD) has always been a proponent of the devices, and noted a year ago that ignition interlock devices had stopped some 2.3 million drunk driving incidents. A year before that the American Journal of Public Health published a peer-reviewed study supporting the continued expansion of ignition interlock programs in this country. The Johns Hopkins Bloomberg School of Public Health found that the laws were an excellent deterrent as well – the devices were preventing drunk driving even before they were installed.

It’s hard to imagine how any legislator would need more data to form a decision. What legislators do need is pressure. Citizens who want to make their state’s roads safer need to contact their lawmakers and press for thorough, well-enforced all-offender ignition interlock laws. The reason is clearer than ever – lives are on the line.