An Evaluation of the Effectiveness of Ignition Interlock in California

This report is the second of a two-study evaluation of ignition interlock in California that was mandated by the California Legislature (AB 762). The first study, which was published in 2002, was presented as a process evaluation that examined the degree to which ignition interlock has been implemented in California. This current study is an outcome evaluation that examines the effectiveness of ignition interlock in reducing alcohol-related crashes and convictions, and crashes overall (alcohol and nonalcohol). The study examines the effectiveness of ignition interlock devices (IIDs) in reducing alcohol-related crashes and convictions, as well as crashes overall, in California. Results indicate that interlock works for some offenders in some contexts, but not for all offenders in all situations. The study reports that IIDs are most effective when they are installed, while there is evidence that judicial order to install an IID are effective for repeat driving under the influence (DUI) offenders, even when not all offenders are compliant and install a device. Reductions in subsequent DUI incidents are associated with an administrative program in California in which repeat DUI offenders comply and install a device. The study also found the first DUI offenders with high blood alcohol levels do not effectively participate in the IID blood alcohol levels.


  • English

Media Info

  • Media Type: Print
  • Features: Figures; References;
  • Pagination: 24p

Subject/Index Terms

Filing Info

  • Accession Number: 01043008
  • Record Type: Publication
  • Source Agency: UC Berkeley Transportation Library
  • Report/Paper Numbers: CAL-DMV-RSS-04-210, AL0357
  • Created Date: Feb 21 2007 7:56PM