Information on breathalyzers, ignition interlock devices, and DWI and license reinstatement laws regarding ignition interlocks.
Saturday December 10th 2016



Do Ignition Interlock Devices Really Work?

IID Device on a seatMore and more states are beginning to use ignition interlock laws and to make existing interlock laws more strict. These actions are praised by some, though they have also created controversy. Much of this controversy comes down to the question:  Do ignition interlock devices (IID), also known as breathalyzer interlocks or in car breathalyzers, really work? However, there are actually two parts to this question, and both deserve answers as states continue to adopt laws requiring IID installation.  First, do the actual devices accurately and reliably detect whether someone has consumed alcohol and how much, and, second, does requiring IIDs prevent drinking and driving?

Do Breathalyzer Interlocks Accurately Reflect Blood Alcohol Content?

Do IIDs accurately reflect the blood alcohol content (BAC) of the user? This is the most obvious meaning of the question, and the answer plays an important role in ignition interlock policy making. The accuracy of the breath test can have a substantial impact on someone using the device as part of their probation. For instance, a failed test can result in a continuation of a license suspension, additional fines, and even jail time. Therefore, IID users as well as public officials have an interest in ensuring the devices accurately reflect alcohol consumption. For this reason, states requiring IIDs for those convicted of Driving Under the Influence (DUI) or Driving While Intoxicated (DWI) mandate the use of specific models and have established regulations governing the approval process.  At the federal level, the National Highway Traffic Safety Administration, an agency of the Department of Transportation, has established specifications for IID certification.

One of the principle controversies regarding IID requirements involves false readings, or false positives. A false positive occurs when the breathalyzer device records a BAC above the preset limit, but, simply put, is wrong. Despite the best efforts of state policy makers and IID manufacturers false readings are possible. A concern of many users and opponents to IID legislation is that false readings can occur due to the use of fairly ordinary substances that are detected by the device as alcohol. However, there are simple ways to avoid a false reading. Here are some examples:

  • Rinse your mouth with water prior to using the device.
  • Use non-alcoholic mouthwash.
  • Ensure that other drivers have not been drinking before using the device.

While false positives are a possibility limiting the possibility of a false reading is largely in the hands of the individual IID users.

Do IID Programs Reduce or Prevent Drinking and Driving?

Does the use of IIDs prevent people from drinking and driving? The goal of mandatory ignition interlock programs is to prevent accidents and deaths caused by drinking and driving. According to the National Highway Traffic Administration Report, Ignition Interlocks – What You Need to Know: A Toolkit for Policymakers, Highway Safety Professionals, and Advocates, “Research shows that ignition interlocks reduce recidivism among both first-time and repeat DWI offenders, with reductions in subsequent DWI arrests ranging from 50 to 90 percent while the interlock is installed on the vehicle.”

The same report cites research showing that “for the period when ignition interlocks are installed on an offender’s vehicle, rates of DWI recidivism are reduced an average of 64 percent.” It should be pointed out that recidivism does increase after the removal of the device.

Its also important to note, that while there is a certain degree of inconvenience and social stigma attached to the use of IID, they also allow at-risk-drivers to continue operating a motor vehicle, which allows the users to maintain employment, attend school, receive treatment, and maintain active social and family lives.

Overall, as with any piece of technology or public policy there are bugs to be worked out and counterpoints to be made. However, preventing false readings from the device is largely within the control of the user, and even basing reductions in repeat offenses on the lowest research, requiring IIDs saves lives.

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