Mandating Treatment Based on Interlock Performance: Evidence for Effectiveness

Vehicle alcohol ignition interlocks reduce alcohol-impaired driving recidivism while installed, but recidivism reduction does not continue after removal. It has been suggested that integrating alcohol use disorder (AUD) treatment with interlock programs might extend the effectiveness of interlocks in reducing recidivism beyond their removal. This study evaluated the first implementation of a Florida policy mandating AUD treatment for driving under the influence (DUI) offenders on interlocks. Treatment was required when the offender accumulated 3 violations (defined as 2 "lockouts" within 4 hours; a lockout occurs when the device prevents a drinking driver from starting the vehicle).

Cox regression was used to compare alcohol-impaired driving recidivism during the 48 months following the interlock removal between 2 groups: (i) 640 multiple DUI offenders who received AUD treatment while interlocks were installed; and (ii) 806 matched offenders not mandated to treatment while interlocks were installed.

The ignition interlock plus treatment group experienced 32% lower recidivism, 95% confidence interval [9, 49], following the removal of the interlock during the 12 to 48 months in which they were compared with the nontreatment group. We estimated that this decline in recidivism would have prevented 41 rearrests, 13 crashes, and almost 9 injuries in crashes involving the 640 treated offenders over the period following interlock removal.

This study provides strong support for the inclusion of AUD treatment for offenders in interlock programs based on the number of times they are "locked out." The offenders required to attend treatment demonstrated a one-third lower DUI recidivism following their time on the interlock compared to similar untreated offenders.