Do Ignition Interlock Devices Help Reduce Car Crashes?

Drunk driving remains a huge problem in the United States.

While the National Highway Traffic Safety Administration (NHTSA) says that drunk driving deaths were at their lowest in 2019, the fact that such preventable tragedies still happen is reason enough to keep people awake at night, especially those with loved ones whom they know to be alcohol drinkers.

Over the years, laws have introduced a variety of penalties for driving under the influence (DUI) offenders that aim to discourage them from doing it again.

While longer jail sentences and heftier penalties do have their intended effects, there’s one consequence of DUI that’s shaping up to be helpful in reducing drunk driving crashes.

It’s called ignition interlock installation, which various studies are saying is effective at reducing DUI recidivism, which, in effect, would help reduce the risk of alcohol-related vehicular accidents as well.

How Does An Ignition Interlock Device Work?

An ignition interlock device (IID) is a breathalyzer wired directly to the engine of a DUI offender’s car.

Once it’s hooked up, the DUI offender will be required to blow into the device to provide a breath sample every time he wants to drive.

If the breathalyzer doesn’t detect any trace of alcohol on the breath sample, the DUI offender can start the car without any problems.

However, if the breathalyzer yields a blood alcohol concentration (BAC) level that hits or breaches a preset limit (usually 0.02%), the car engine will not start no matter how hard the DUI offender tries.

IIDs also do “rolling retests,” which require the driver to provide another breath sample from time to time while in the middle of a drive as a way of ensuring his sobriety on the road.

Studies That Attest To The Effectiveness of IIDs

Many of the studies on ignition interlock devices are focused on their effectiveness in reducing DUI recidivism.

In one study conducted by Jeffrey H. Coben and Gregory L. Larkin, interlock program participants were found to be 15%–69% less likely to face another DUI arrest.

The Centers for Disease Control and Prevention (CDC) also mentions the results of eight separate studies conducted by Marques, Voas, et al. that show a 65% percent reduction in recidivism among offenders with revoked driver’s licenses who installed IIDs.

More encouraging are the results of a study published in 2017 that explored the effects of ignition interlock laws on fatal motor vehicle crashes from 1982 to 2013.

The study’s authors found that states with ignition interlock laws that require IID installation for all drunk driving offenders have seen a 7% decrease in fatal crashes among drivers who had a BAC of 0.08% or higher.

Mothers Against Drunk Driving (MADD), a nonprofit organization that aims to, among other things, end drunk driving, has also come up with a lengthy list of studies about ignition interlock devices and their findings, which include:

– A 15% decrease in drunk driving deaths in states with interlock laws in place for all DUI offenders

– For first-time DUI offenders, ignition interlocks are 74% more effective than mere license suspension when it comes to reducing DUI recidivism.

– The number of accidents caused by alcohol-impaired drivers will fall with the installation of IIDs on the cars of all DUI/DWI offenders.

– In Sweden, recidivism dropped to nearly zero due to ignition interlock installation for first and multiple offenders.

If the studies mentioned above are to be believed, then ignition interlock devices indeed help in reducing car crashes.

All states already have some form of ignition interlock law, although they may implement them differently, with some making IID installation optional for first-time DUI offenders.

If enforced properly, these laws may well hold the key toward further reducing or maybe even ending drunk driving for good.