Ignition Interlock Devices Help Reduce DUI in Short Term and May Have Unlocked Potential

Newswise — A new study suggests that devices that prevent drivers from starting their vehicles after drinking, help to reduce drunk driving in the short term and may have additional potential based on a broader research approach. Vehicle crashes involving alcohol-impaired drivers result in 10,000 deaths a year in the US. About a quarter of convicted Driving Under the Influence (DUI) offenders are sentenced to install ignition interlock devices (IIDs), which prevent them from driving if their breath alcohol level exceeds a certain threshold. Interlock devices are effective while installed, though it is unclear to what extent they influence longer term changes in drivers’ alcohol use. Understanding the impact of the IID on offenders’ behavior can potentially help inform strategies for decreasing DUI recidivism. The study in Alcoholism: Clinical & Experimental Research is the first known investigation of offenders’ drinking and driving from before their arrest to the period of time after the interlock device is removed.

Researchers worked with 153 adults in upstate New York convicted of a DUI offense. Many were multiple offenders and most were heavy drinkers. Three times, each participant took a survey and underwent a detailed interview covering their daily alcohol consumption and whether after drinking they drove within two hours — a method of self-reported alcohol use with established accuracy. The surveys and interviews took place around the time of the IID installation, during the period of time the IID was installed, and after its removal. Investigators calculated participants’ average rates of alcohol use and frequency driving after drinking. They used statistical analysis to explore the participants’ behavioral changes over four phases: before the DUI arrest; from arrest to IID installation; the period of IID installation; and after IID removal.

Participants reported that in the eight weeks leading up to their arrests, they consumed on average two drinks per day and drove while over the legal alcohol limit about three times a month. The period between their DUI arrests until the IID installation averaged 3–4 months. In this second phase, participants’ average alcohol consumption per day halved, and their frequency of driving after drinking declined by 82% — stark behavioral shifts likely related to the legal and other consequences for a DUI arrest. Subsequently, the interlock devices were in use for 6-12 months. During this third phase, participants’ alcohol consumption declined only modestly. Their frequency of combining driving and drinking fell a further 58%, however, perhaps because their attempts to do so were largely blocked by the devices. Their recidivism rates at this point were lower than those of comparable offenders sentenced to license suspension. After the IID was removed (about 6-8 months after installation), the participants’ alcohol use was found to have increased marginally. They were more likely to drive after drinking, rebounding to rates similar to the second phase, but lower than before their arrest. This recidivism rate is comparable to that of offenders whose licenses were suspended.

The researchers recommend considering offenders’ drinking patterns before arrest, as well as after, when designing intervention programs that may enhance the effectiveness of the interlock penalty. The longer-term impact of IIDs merits further research, incorporating IID lockout data, to better predict offenders’ behavioral patterns. Parts of this study were based on a modest sample size and the findings may not be generalizable.

Changes in alcohol use and drinking and driving outcomes from before arrest for driving under the influence to after interlock removal. R. Voas, A. Tippetts, E. Romano, T. Nochajski, A. Manning, E. Taylor, M. Scherer (pp. xxx)

ACER-20-4616-R2