Ignition interlock devices

Evidence Rating  
Evidence rating: Scientifically Supported

Strategies with this rating are most likely to make a difference. These strategies have been tested in many robust studies with consistently positive results.

Health Factors  
Decision Makers
Date last updated

Ignition interlocks are devices that can be installed in vehicles to prevent operation by a driver who has a blood alcohol concentration (BAC) above a specified level. Interlocks are most often installed in vehicles of people who have been convicted of alcohol-impaired driving. Interlocks can be mandated by courts or offered by state licensing agencies as an alternative to a suspended driver’s license, often as a provision of a restricted license. Requirements for use of interlock devices varies by state based on BAC level, number of offenses, and other conditions. Interlocks are generally installed for the length of time a license would be suspended, usually 6 to 24 months1. States can levy penalties on offenders for failure to install devices2.

What could this strategy improve?

Expected Benefits

Our evidence rating is based on the likelihood of achieving these outcomes:

  • Reduced impaired driving

  • Reduced alcohol-related crashes

What does the research say about effectiveness?

There is strong evidence that installing ignition interlock devices for people convicted of alcohol-impaired driving reduces re-arrest rates while interlocks are installed1, 3. When removed, however, re-arrest rates are similar to those convicted of alcohol-impaired driving who do not use interlocks1, 3, 4. Ignition interlock devices have also been shown to reduce alcohol-related crashes5, 6, 7.

Drivers with interlocks appear to have fewer alcohol-related crashes than drivers whose licenses have been suspended for an alcohol-impaired driving conviction1, 4. States with laws that require interlock use for all drunk driving offenders, including first-time offenders, have greater reductions in crash rates and crash-related deaths than states with laws that require interlock use for high-risk offenders (e.g., repeat offenders) only5, 6, 8. A Washington-based study also indicates that interlock installation requirements for first-time offenders decreases recidivism and crashes7.

How could this strategy impact health disparities? This strategy is rated no impact on disparities likely.
Implementation Examples

As of 2017, every state has an ignition interlock law, although specifics vary. Twenty-nine states and Washington, D.C. have mandatory ignition interlock provisions for all convicted drunk driving offenders. Florida, Hawaii, New Jersey, North Carolina, Wisconsin, and Wyoming require ignition interlocks for first-time convicted offenders with a certain BAC level or higher9.

Implementation Resources

CDC-Ignition interlock - Centers for Disease Control and Prevention (CDC). Increasing alcohol ignition interlock use.

NCSL-Ignition interlock - National Conference of State Legislatures (NCSL). State ignition interlock laws.


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1 CG-Motor vehicle injury - The Guide to Community Preventive Services (The Community Guide). Motor vehicle injury prevention.

2 CDC-Ignition interlock - Centers for Disease Control and Prevention (CDC). Increasing alcohol ignition interlock use.

3 Miller 2015c - Miller PG, Curtis A, Sønderlund A, Day A, Droste N. Effectiveness of interventions for convicted DUI offenders in reducing recidivism: A systematic review of the peer-reviewed scientific literature. The American Journal of Drug and Alcohol Abuse. 2015;41(1):16-29.

4 IAS-Anderson 2006 - Anderson P, Baumberg B. Alcohol in Europe: A public health perspective. London, UK: Institute of Alcohol Studies (IAS); 2006.

5 McGinty 2017 - McGinty EE, Tung G, Shulman-Laniel J, et al. Ignition interlock laws: Effects on fatal motor vehicle crashes, 1982-2013. American Journal of Preventive Medicine. 2017;52(4):417-423.

6 Ullman 2016 - Ullman DF. Locked and not loaded: First time offenders and state ignition interlock programs. International Review of Law and Economics. 2016;45:1-13.

7 McCartt 2013 - McCartt AT, Leaf WA, Farmer CM, Eichelberger AH. Washington State’s alcohol ignition interlock law: Effects on recidivism among first-time DUI offenders. Traffic Injury Prevention. 2013;14(3):215-229.

8 Kaufman 2016 - Kaufman EJ, Wiebe DJ. Impact of state ignition interlock laws on alcohol-involved crash deaths in the United States. American Journal of Public Health. 2016;106(5):865-871.

9 MADD-Ignition interlock 2017 - Mothers Against Drunk Driving (MADD). 2017 Ignition interlock report. 2017.