Effects of Washington State's alcohol ignition interlock laws on DUI recidivism: An update

The objective of this study was to examine the effects of changes to Washington State's alcohol ignition interlock laws: moving issuance of interlock orders from the courts to the driver licensing department (July 2003); extending the interlock order requirement to all persons convicted of driving under the influence (DUI; June 2004); allowing an interlock in lieu of an administrative driver's license suspension (January 2009); and requiring proof of interlock installation to reinstate the driver's license (January 2011).

Trends in conviction types, interlock installation rates, and 2-year cumulative recidivism rates were examined for first-time and repeat offenders with convictions stemming from DUI arrests during 1999-2012. Autoregressive integrated moving average (ARIMA) models examined the association between law changes and installation rates, law changes and recidivism rates, and installation rates and recidivism rates.

During the study period, there was a large increase in the proportion of first-time DUI arrests reduced to alcohol-related negligent/reckless driving convictions, offenses not requiring interlock orders. The interlock installation rate increased substantially and the recidivism rate declined substantially among both first and repeat offenders. Based on the ARIMA models for first offenders, the 2004 and 2009 law changes were associated with increased interlock installation rates and lower recidivism rates. For first offenders arrested during the last quarter of 2012, the model estimates a 26% reduction in the recidivism rate (from an expected 7.7% without the 4 laws to 5.6%). A 1 percentage point increase in the interlock installation rate was associated with a 0.06 percentage point decline in the recidivism rate among first offenders. If the association carried forward and if the installation rate had been 100% rather than 38% in the last quarter of 2012, the 2-year recidivism rate would have been reduced from 5.6 to 2%. Among repeat offenders, the 2003 and 2009 law changes were associated with increased interlock installation rates, and the 2009 law change was associated with a nonsignificant decline in recidivism.

In Washington, rates of interlock installations increased as interlock laws were strengthened, and the increase was associated with reductions in recidivism among first DUI offenders. Washington's experience suggests that states can reduce DUI recidivism by requiring interlock orders for all offenders, allowing offenders to install interlocks in lieu of an administrative driver's license suspension, and closing statutory loopholes that allow plea reductions to convictions without interlock orders.