Reducing Alcohol-impaired Driving: Ignition Interlocks
Ignition interlocks can be installed in vehicles to prevent operation of the vehicle by anyone who has a blood alcohol concentration (BAC) above a specified level (usually .02 – .04%). Interlocks are typically used to prevent alcohol-impaired driving by people who have been previously convicted of alcohol-impaired driving.
Task Force Recommendations & Findings
The Task Force on Community Preventive Services recommends the use of ignition interlocks for people convicted of alcohol-impaired driving on the basis of strong evidence of their effectiveness in reducing rearrest rates while the interlocks are installed. Public health benefits of the intervention are currently limited by the small proportion of offenders who install interlocks in their vehicles; more widespread and sustained use of interlocks among this population could have a substantial impact on alcohol-related crashes.
About the Interventions
Interlocks may be either mandated through the court system or offered as an alternative to a suspended license by a state licensing agency. The amount of time they are installed typically matches the period of license suspension—generally ranging from 6 to 24 months. Only a small proportion of people eligible for ignition interlock programs typically participate. However, uptake rates vary substantially, based on how programs are administered.
Results from the Systematic Reviews
Population-based Campaigns
The results that informed the above Task Force recommendation came from two different reviews. The results related to alcohol impaired driving were drawn from a 2004 review conducted by Willis, Lybrand and Bellamy in 2004*. A team of scientists and experts from the Community Guide conducted a follow-up systematic review of studies that evaluated crash outcomes. The Community Guide identified additional studies through this review. Results of these two reviews include:- Re-arrest rates with installed interlocks: median decrease of 73% (10 studies)
- Upon removal, re-arrest rates return to levels similar to those of offenders who have not had interlocks installed (6 studies).
- Drivers with interlocks installed have fewer alcohol-related crashes than those with suspended licenses (1 study).
- Overall crash rates were similar to those for the general driving population. Drivers with ignition interlocks have a substantially greater number of crashes overall than do drivers with suspended licenses, however, likely due to driving more often (2 studies).
These results are based two different systematic reviews, one prepared by the Cochrane Collaboration (Willis, Lybrand and Bellamy, 2004) and the other led by scientists from CDC’s Division of Unintentional Injury Prevention with input from a team of specialists in systematic review methods and experts in research, practice and policy related to reducing alcohol-impaired driving.
These results are based on a systematic review of all available studies led by scientists from CDC’s Division of Unintentional Injury Prevention with input from a team of specialists in systematic review methods and experts in research, practice and policy related to reducing alcohol-impaired driving.
* Willis C, Lybrand S, Bellamy N. Alcohol ignition interlock programmes for reducing drink driving recidivism. The Cochrane Database of Systematic Reviews 2004, Issue 3.
Supporting Materials
Publication
More Community Guide publications about the Prevention of Motor Vehicle-related Injuries
Disclaimer
The findings and conclusions on this page are those of the authors and the Task Force on Community Preventive Services and do not necessarily represent the official position of CDC.
Sample Citation
The content of publications of the Guide to Community Preventive Services is in the public domain. Citation as to source, however, is appreciated. Sample citation: Guide to Community Preventive Services. Reducing alcohol-impaired driving: ignition interlocks. www.thecommunityguide.org/mvoi/AID/ignitioninterlocks.html. Last updated: MM/DD/YYYY.
Review completed: June 2007
- Page last reviewed: April 13, 2009
- Page last updated: January 14, 2010
- Content source: The Guide to Community Preventive Services
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