During alcohol interlock use, elevated BACs in morning or declining vehicle use over time predicts post-interlock recidivism.

The alcohol interlock record is the first extensive behavioral record that has ever been available to help researchers understand DWI offenders. The average interlock device in Alberta Canada logs over 2300 breath tests during an average 9 months of interlock use. Analysis of the patterns of violations makes available new predictive information for scaling driver risk. Recent work (Marques et al., 2001, Marques et al., 2002) has shown the overall rate of elevated BAC tests during the first several months of use strongly predicts repeat DWI after the interlock has been removed. This report further analyzes the record of 5.5 million BAC tests in Alberta and finds that even after accounting for strong predictors of post-interlock recidivism such as prior repeat DWI and the overall prediction based on higher rates of failed interlock BAC tests, if the BAC tests failures occur in the morning (e.g., BAC still >=.04 gm/dl presumably from previous night drinking) there is an additional 45% higher likelihood of later having a new repeat DWI. Also, evidence is presented that offenders who decrease their overall interlock vehicle use (fewer tests taken over interlock use time) have a higher likelihood of recidivism post-interlock. (Author/publisher) For the covering abstract of the conference see ITRD Abstract No. E201067.