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Ignition interlock devices

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Description

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 months (CG-Motor vehicle injury). States can levy penalties on offenders for failure to install devices (CDC-Ignition interlock).

Expected Beneficial Outcomes

Reduced impaired driving
Reduced alcohol-related crashes

Evidence of Effectiveness

There is strong evidence that installing ignition interlock devices for people convicted of alcohol-impaired driving reduces re-arrest rates while interlocks are installed (CG-Motor vehicle injury, Miller 2015c). When removed, however, re-arrest rates are similar to those convicted of alcohol-impaired driving who do not use interlocks (CG-Motor vehicle injury, Miller 2015c, IAS-Anderson 2006). Ignition interlock devices have also been shown to reduce alcohol-related crashes (McGinty 2017, Ullman 2016, McCartt 2013).

Drivers with interlocks appear to have fewer alcohol-related crashes than drivers whose licenses have been suspended for an alcohol-impaired driving conviction (CG-Motor vehicle injury, IAS-Anderson 2006). 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) only (McGinty 2017, Kaufman 2016, Ullman 2016). A Washington-based study also indicates that interlock installation requirements for first-time offenders decreases recidivism and crashes (McCartt 2013).

Implementation

United States

As of 2017, every state has an ignition interlock law, although specifics vary. Twenty-nine states and Washington DC 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 higher (MADD-Ignition interlock 2017).

Wisconsin

As of 2017, interlocks are mandatory in Wisconsin for all repeat offenders, first time offenders with a BAC of 0.15 or higher, and all drivers who refuse a breath or blood test at a traffic stop (WisDOT-Ignition interlock). First-time offenders with a BAC of 0.15 or higher are required to install interlocks for a minimum of one year; interlocks are also often used for individuals with multiple offenses within 5 years. (NCSL-Ignition interlock).

Implementation Resources

Citations - Description

Citations - Evidence

Citations - Implementation

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