Ignition Interlock Findings Criticized

Ignition Interlock Findings Criticized – The California DMV’s Response

Sacramento, CA-The California Department of Motor Vehicles (CA DMV) says a March 15th press release from the American Beverage Institute (ABI)
misrepresented the results of a new DMV study of the effectiveness of ignition interlock devices in reducing the incidence of driving under the influence.

The ABI press release said “dramatic findings in a recently released study by the California Department of Motor Vehicles show that interlock devices had no statistically significant effect in preventing subsequent
drunk driving convictions, but they increase their users’ general crash risk by 130%.” DMV officials said that statement seriously misrepresents the published conclusions of their study.

“It’s true that we found court orders to install an ignition interlock device have no significant effect in preventing repeat DUIs among first-time DUI offenders,” said the report’s lead author, David DeYoung. “But what the ABI press release completely omitted was our finding that when second-time offenders install the device in order to be able to drive with a restricted license, they have a significantly lower risk of repeat DUI incidents – a 41 percent reduction. Since DUI repeat offenders are a major cause of U.S. highway deaths, this misrepresentation by the ABI press release greatly concerns the California DMV.

“In quoting our finding that DUI second offenders using the device have a 130% higher risk of a subsequent crash, ABI seems to imply that the device itself somehow increases the likelihood of a crash. That is
not what we said. It is not that installation and use of interlocks causes crashes or that the devices themselves are unsafe,” said DeYoung. “Obviously if someone who has previously been forbidden to drive is allowed to return legally to the roadways with an ignition interlock and a restricted driver license, their exposure to accidents increases, no matter how sober they are.”

The ABI release quoted the DMV report as saying: “Because there is no evidence that interlocks are an effective traffic safety measure for first DUI offenders, the use of the devices should not be emphasized.” But the ABI release neglected to mention that the DMV report specifically stated that the devices “are effective in reducing subsequent DUI convictions.”

DeYoung, manager of alcohol and drug projects in DMV’s Research & Development unit, said: “We are concerned because the ABI press release quotes our report out of context, presents incorrect information and misstates the findings of our report so completely that the entire tenor of the ABI release is seriously inconsistent with what the report actually says. We are especially concerned because the ABI release uses that misrepresentation as a pretext for urging legislators to “abandon” any attempts to require the devices before a third offense. On the
contrary, the DMV report specifically stated that requiring second offenders to install the device if they want to be able to drive with a restricted license significantly reduces further DUIs.”

DeYoung added: “It’s true that our study showed that court orders to first offenders to install an ignition interlock device are not effective in reducing recidivism among that group – perhaps because many first offenders tend to be in denial, resent the devices and refuse to install them. But the ABI press release completely omits our finding that the devices can have a real effect on repeat offenders who are beginning to come to grips with their alcohol problem and who often find the mechanical devices to be helpful in keeping them out of cars when they’ve been drinking. We urge judges, police, alcohol rehabilitation experts and anyone concerned about the nation’s increasing death toll from drinking drivers to study our report.”

Under current law, California judges are required to order ignition interlocks for drivers convicted of driving while suspended, if the license was suspended for DUI. Judges may order interlocks for first-time DUI offenders with high blood alcohol levels at time of arrest, and for repeat DUI offenders. In addition, there is an administrative program where repeat DUI offenders can, after serving half their license suspension period, install an interlock and obtain a restricted driver license from DMV.

View a complete copy of the CA DMV Ignition Interlock report
(PDF download):


  • An Evaluation of the Effectiveness of Ignition Interlock in California
    (September, 2004)

  • An Evaluation of the Effectiveness of Ignition Interlock in California
    (May, 2002)

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