What are ignition interlock devices?

August 4, 2022
What are ignition interlock devices?

If you have been convicted of a drunk driving offense and have had your driver’s license revoked as a result, you may be forced to have an ignition interlock device installed in your vehicle. These devices are wired directly to your car’s ignition system and require you to submit a breath sample before the car will start. Once you blow through a tube connected to a dashboard monitor, the device will determine your blood alcohol content level and will only start if it is at or below a certain level. Periodically throughout the drive, the device will signal you to submit subsequent breath samples in order for the car to continue operating. The device records this information, including start-up attempts, failed attempts to start the car and BAC levels, and transmit it to law enforcement when you bring your vehicle in for interlock device maintenance appointments.

Although having an ignition interlock device installed and maintained can be costly, it gives you the freedom and ability to drive, once your driver’s license has been reinstated. You are able to get to work, school and run critical errands that you would otherwise have to find another form of transportation.

In many states across the country, IIDs are mandatory for all drunk driving offenses. However, in Missouri, it is left to the discretion of a judge to determine whether a first-time offender will need to use an interlock device. If you have been convicted of more than one DUI offense, you are required to have an IID for at least six months after you receive your driver’s license.

This information is intended to educate and should not be taken as legal advice.


For personalized legal guidance, call our office at 417-882-9300 or submit this form to schedule a meeting with an attorney.

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