Changes in Alcohol Use and Drinking and Driving Outcomes From Before Arrest for Driving Under the Influence to After Interlock Removal

Background Half of the offenders convicted of impaired driving in the United States are sentenced to install alcohol ignition interlock devices (IIDs), which prevent them from starting their vehicles if they have been drinking. No research has yet explored offenders’ patterns of alcohol consumption and driving under the influence of alcohol (DUI) from the time before the arrest to the time period after the IID is installed. This study aims to fill that gap in knowledge. Methods Using the Timeline Follow‐back interview procedure, we assessed the daily drinking of 153 convicted DUI offenders’ self‐reported total alcohol consumption and rates of self‐reported driving after drinking over 4 phases: before DUI arrest, between arrest and IID installation, during the phase on the interlock, and after the interlock is removed. Because information about behaviors in each period was not available for every participant, comparisons were made using paired‐sample contrasts. Results Compared with before the arrest, total alcohol use decreased by 50% in the 4‐month phase following arrest and before IID installation, though it did not change much afterward. The frequency of drinking and driving decreased sharply after the arrest (−82%), with further decrease upon installation of the interlock (−58%, p = 0.05). The frequency of drinking and driving after the IID was removed returned to preinstallation drinking and driving status (+58%, p = 0.01). Conclusions Participants made significant adjustments to their drinking behavior by adhering to the traditional DUI driving restrictions in the postarrest phase. Although installation of an IID was not associated with a significant change in drinking, it further reduced the frequency of drinking and driving. Evaluations of the IID experience should take into account information on an individual's drinking and DUI behaviors not only before the IID was installed, but before the individual was arrested. For DUI offenders, the impact of being sentenced to an interlock device starts at the time of the arrest, after which a sharp decline in alcohol consumption and in drinking and driving occurs. Once on the interlock, consumption declines only modestly, but driving after drinking falls a further 58%. After the interlock was removed, alcohol use and driving after drinking begin to rebound, but both remain well below prearrest levels.