The Car and Truck Fleet and Leasing Management Magazine

CDC: Ignition Interlocks Reduce DWI Arrests

March 16, 2011

ATLANTA - Researchers at the Centers for Disease Control and Prevention have concluded that ignition interlocks help prevent drivers who were previously arrested for driving while intoxicated (DWI) from being re-arrested.

The researchers in CDC's Community Guide branch said their conclusion is based on a review of 15 scientific studies on ignition interlocks. Researchers found that after these devices were installed, the re-arrest rates for alcohol-impaired driving decreased by a median of 67 percent relative to drivers with suspended licenses. The review is in the March issue of the American Journal of Preventive Medicine.

Ignition interlocks can be installed in vehicles to prevent someone from operating a vehicle with a blood alcohol concentration (BAC) above a specified level. This level is usually 0.02 to 0.04 grams per deciliter (g/dL); the minimum illegal BAC level is 0.08 g/dL in every state. The devices work by sampling the driver's breath before the vehicle can be started and periodically while the vehicle is operating.

Interlocks are most often used to prevent impaired driving by people who have already been convicted of DWI. They may be mandated through the court system or offered as an alternative to a suspended driver's license.

The Task Force on Community Preventive Services, an independent nonfederal body of public health experts, recommends the use of ignition interlocks for people convicted of alcohol-impaired driving.

Impaired-driving crashes resulted in nearly 11,000 deaths in the United States in 2009 -nearly one-third of all traffic deaths. The annual cost of impaired driving is estimated at more than $110 billion. Preventing impaired driving -- and the injuries and deaths that it can cause -- is a priority for CDC.

"Each day, more than 30 people die because of alcohol-impaired driving. We know that interlock devices can save lives," said CDC Director Thomas R. Frieden, who is a medical doctor "More widespread use of ignition interlocks will reduce alcohol-related crash deaths and injuries."

As of December 2010, 13 states require interlocks for all convicted offenders, including a first conviction. More than half of all states require some offenders - such as those with multiple convictions or with an extremely high BAC at the time of arrest - to install ignition interlocks. Nonetheless, only a small proportion of DWI offenders participate in interlock programs.

"When offenders' licenses are suspended, they aren't legally able to provide transportation for themselves and others who may rely on them to get to places like school and work," said Randy Elder, scientific director of systematic reviews with the Community Guide branch and lead author on the review. "Ignition interlocks allow offenders to keep operating their vehicles legally. At the same time, they effectively ensure that they do so more safely - not under the dangerous effects of alcohol."

The CDC recommends more widespread use of interlocks and favors ignition interlocks for everyone convicted of DWI, even for first convictions.

For more information about this review, visit

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