Drivers in Tennessee convicted of a DUI-related offense, including driving with a blood alcohol content level of .08 or higher (.04 if the driver is a commercial driver), can be ordered to use an ignition interlock (IID) device for up to one year. A driver may also request to use an IID in order to obtain a restricted license for an offense that wouldn’t normally require an IID; this allows them to drive without geographic restrictions or other limitations on the restricted license.

At Banks and Jones, we can explain if you are required to use an ignition interlock device for a DUI conviction, or if using the device is advisable even though it’s not required. Normally, the driver who uses an IID has to pay for the installation of the IID, as well as any calibration tests and data downloads that have to be performed. There are different IID device dealers throughout Knoxville. We can help you select a reliable dealer.

How does an ignition interlock device work?

The IID is an in-car breathalyzer machine that is connected to your vehicle’s ignition/starter system. You’ll need to install an IID on each vehicle that you drive. According to ALCOLOCK (an IID provider), an IID has two parts:

• A handheld device with a mouthpiece. The driver blows into the mouthpiece. This device senses any alcohol on your breath.The device transmits your blood alcohol content (BAC) to an electronic control unit.
• An electronic control unit (ECU) connected to the starter. If the device detects alcohol on your breath, the ECU prevents you from starting your car. If no alcohol on your breath is detected, you can start your vehicle.

IIDs use an ethanol fuel cell sensor “to provide the precision and accuracy required by the National Highway Transportation Safety Administration’s (NHTSA) model specifications for breath alcohol IIDs.” Fuel cell sensors “use an electrochemical process where any amount of alcohol on your breath reacts with a catalytic electrode. That reaction produces an electric current. The IID measures that current to determine your BAC.”

Generally, the more alcohol the IID detects on your breath, the higher your BAC level will be. To be clear, your car will not start if your BAC is approximately .02 – not .04 or .08. For most people, just one alcoholic drink is enough to register a .02 level. Alcohol “immediately enters your bloodstream, and your bloodstream carries that alcohol to every part of your body, including your lungs.”

Installing an IID is normally done discreetly. Using the device is fairly routine. It’s generally not easy to cheat the IID. The manufacturers of IIDs are continually installing security features on their devices.

How often do drivers need to use an IID?

Drivers need to blow into the mouthpiece every time they start their car. Drivers must also provide random/rolling tests while the car is in motion to ensure the driver doesn’t start drinking after the initial start-up test. The IID gives the driver an audible and visual alert for several minutes prior to the time the driver has to provide the breath sample.

The driver can keep driving if they pass the rolling tests. If the driver fails the rolling test, the car does not stop operating for safety reasons. Instead, the IID will start blaring sounds and flashing lights, necessitating the driver pull off the road to a safe location.

What information does the IID record?

An IID records the date, time, and results of each start-up test and each rolling test. An IID also records your location if the device has a GPS. The IID takes your picture each time you take the test to ensure you (and not someone you know who doesn’t have any alcohol on their breath) take the test. An IID also records if you fail to take a rolling test, try to remove or tamper with the IID, and may record other information depending on Tennessee’s requirements.

Normally, drivers need to have their IID recalibrated at a local service center every 30 days. At that time, all the information the IID has recorded is downloaded. The downloaded information is disclosed to the probation officer or other court-required monitor. The data is also disclosed to the Tennessee Department of Motor Vehicles.

Drivers who fail their IID test too many times may not be able to use the IID (and thus will not be able to drive) for up to 24 hours. IID test failures can also result in a revocation of a restricted license, a reinstatement of a driver’s license suspension, and other consequences.

If your device breaks due to a car accident or malfunctions, you will need to promptly notify the manufacturer or your IID service provider. You can’t drive until the IID is repaired or replaced. If you drive, your right to continue driving may be suspended or revoked. You may be charged with a probation violation.

Can an IID result be wrong?

Yes. There are several reasons why drivers may have a justifiable reason for failing an IID test.

According to ALCOLOCK, you should be able to wash your mouth with water and submit a second test if you fail the first test. If you believe there is a reasonable explanation for failing an IID test, you should contact your DUI lawyer and the monitoring agency. If you have too many failures, you could be in violation of the IID program.

Some foods and medical conditions may result in a failed BAC test even though you haven’t been drinking. These items include mouthwash, some cough medicines, breath sprays, menthol cough drops and food that may have alcohol like penne with vodka sauce or certain energy drinks.

A medical condition such as diabetes or acid reflux may also yield a positive BAC test result even though you haven’t been drinking. Even some hand sanitizers can cause a positive BAC test result.

Banks and Jones can explain when and how you can contest a false positive IID result.

We may also assert that the IID was not in proper working order.

The best way to avoid having to use an IID device, if you are charged with a DUI offense, is to hire an experienced DUI defense lawyer. At Banks and Jones, we’ve been fighting for criminal defendants for more than 20 years. If your case is dismissed or you are found not guilty, then generally the duty to install an IID will not apply. We may also negotiate a plea bargain for an offense that doesn’t require an IID. If you have questions about when you need to use an IID and how an IID works, call us or use our contact form to schedule a free consultation.