This project evaluated the effects of two new driving-under-the-influence (DUI) laws implemented in California. The first law, effective January 1, 1990, reduced California's illegal per se limit to 0.08% blood alcohol concentration (BAC) and the second, effective July 1, 1990, imposed an administrative per se (APS) pre-conviction license suspension on DUI offenders. Intervention time series analysis was used to evaluate the deterrent impact of these laws on the general population of DUI offenders as measured by the effects on alcohol-related traffic accidents. In spite of the new laws being imposed in an environment of already strict sanctions for DUI, relatively high use of post-conviction license suspension actions, and a long-term downward trend in alcohol-involved accidents, the results of this evaluation showed a significant general deterrent effect associated with the implementation of the APS law, with somewhat less support for such an effect associated with the 0.08% BAC per se limit law. Larger proportions of the observed accident reductions were associated with the timing of the APS law than with the lowering of the illegal per se limit. Some, but not all, of these reductions were statistically significant, even after accounting for additional socioeconomic factors shown to contribute to the consistent downward trend observed in both the alcohol- and nonalcohol-related accident series. There was suggestive evidence that a media campaign initiated one year after implementing the APS law may have enhanced that law's effectiveness. (Author/publisher)
Abstract