Ignition interlock laws are popularly referenced by legislators as a way to discourage drunk driving and to prevent it altogether. A new study identified that the number of impaired drivers involved in fatal vehicle crashes decreases by 16% when states require ignition interlock devices for all DUI offenders, even those who are facing their first charge.

Furthermore, the likelihood of fatal crashes drops by 8% when the state requires ignition interlocks for first offenders with high blood alcohol content and repeat offenders. The number of impaired drivers involved in fatal accidents drops by 3% when states require interlocks for repeat offenders only.

This Insurance Institute for Highway Safety study identified that the most significant decreases occur when the courts require that ignition interlock devices be installed on vehicles for all DUI offenders. Ignition interlock devices work by requiring a driver to blow into the device in order to start their vehicle. That device then reads the person’s blood alcohol content and will not start the car if alcohol is detected.

A recent study by the Center for Disease Control and Prevention agreed about the effectiveness of interlock devices, arguing that they can decrease repeat drunk driving offences by as much as 67%, and they can also lead to significant reductions when compared with license suspension laws, since up to 75% of offenders, who have had their license suspended, will still continue to operate a vehicle taking the chance of being pulled over and caught.