How Effective are IIDs at Preventing DWI?

Posted by Ryan Russman | Jun 09, 2014 | 0 Comments

When a person is convicted of driving while intoxicated, one of the penalties they face is the use of an ignition interlock device. These devices are designed to stop offenders from repeating their offense.  An ignition interlock is also known as a breath alcohol ignition interlock device or an IID. It is installed in the vehicle of a driver convicted of DWI and requires the driver to breathe into it so that the device can read the driver's blood alcohol concentration (BAC). If the device finds that the driver's BAC is over the preset limit, it will not allow the vehicle to be start. These devices have been around for more than 20 years and are believed to be the best way to prevent drunk driving.

Anti-DWI advocacy groups such as Mothers Against Drunk Driving (MADD) and the National Highway Traffic and Safety Administration (NHTSA) believe that anyone convicted of DWI in the United States should, as a condition of their sentencing, install an ignition interlock. Currently, every state has its own laws regarding the use of these devices and laws range from mandatory use for all offenders, to mandatory use for high BAC offenders only, to, most commonly, mandatory use for all repeat offenders.

While a lot of emphasis is put on why these devices should be used, not much information exists explaining how effective they really are at eliminating drunk driving.  It seems the devices themselves are very accurate at preventing drivers with BACs over the limit from driving their vehicles. In a 2014 report by the NHTSA, ignition interlocks are described as being composed of four elements to make them the most effective as possible:

  • A breath alcohol sensor that only allows the vehicle to start when an acceptable breath sample has been provided
  • A secure outer unit that prevents tampering
  • A system that records the samples given in order to monitor if the offender ever attempts to drive drunk
  • A pretest system which requires the driver to provide additional samples every 10 to 15 minutes once the engine has started

In New Hampshire, the system is designed so that anyone with a BAC of 0.02 or more cannot start and operate a vehicle. Research has shown that both first time and repeat offense drivers who use an ignition interlock device have a much lower rate of recidivism than those who do not use the device. However, they do little to change the actual driving habits of an offender. As the NHTSA states in their report:

Once ignition interlocks are removed from a vehicle, however, recidivism rates of ignition interlock users increase and resemble the rates for offenders for whom interlocks were not required.

This suggests that, a driver using an ignition interlock device will refrain from driving while impaired only because the device will not allow them to. Once the device is removed, they continue their, sometimes dangerous, driving habits. Therefore, the use of these devices only temporarily reduces the recidivism rate of offenders. Furthermore, while the system is designed to record how often the driver fails the breath test in the device, most states do not impose a penalty meaning that even a driver who repeatedly attempts to drive drunk with an IID installed will still be allowed to remove the device when their sentence is up.

An ignition interlock is a good way of allowing offenders to continue to drive while guaranteeing that they will not repeat their offense but overall they do not work to change driving habits. Though groups like MADD want all states to require the use of IIDs, there is no mention of how long an offender should be required to use the device. In New Hampshire, where repeat DWI offenders must install a device for two years, its use may be long enough to get an offender out of the habit of driving under the influence. However, no studies have been done to explore the relationship between the length of ignition interlock use and recidivism rate after the device is removed.

While IID devices may not have the long term effects that are needed to stop repeat DWI entirely, they are still a great option for offenders. In many states they can be installed in lieu of serving a longer period of license suspension. If you have been arrested for DWI in New Hampshire and would like more information on ignition interlock device use as well as other penalties of a conviction, contact an experienced DWI attorney at Russman Law right away.

About the Author

Ryan Russman

Attorney Ryan Russman has dedicated his career to fighting for the rights of New Hampshire citizens. His practice, based in Exeter (Rockingham County) New Hampshire, is limited to cases involving DWI and DUI, other motor vehicle and criminal cases, and many cases involving personal injury. He is, however, best known as one of New Hampshire's leading legal authorities on DWI.


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