What is an ignition interlock device?

We have all probably heard of breath-testing devices that are used by law enforcement to determine if a driver they suspect of driving under the influence (DUI) in Tennessee has violated the 0.08 blood alcohol content (BAC) limits.

These breath-testing devices do not actually measure a BAC, since they don’t test the blood, but they do provide an approximation of the alcohol in the blood. This information may provide the, evidence along with the results of a field sobriety test, that an officer will use to execute an arrest of a driver for a DUI.

Another variation on this breath-testing capability is that of the ignition interlock device. The ignition interlock is essentially a breath-tester hooked up to the ignition of a vehicle. With the device installed, in order to start the car, the driver must first supply a breath sample to the device.

If it detects no alcohol, it allows the vehicle to start. Throughout the drive, at random intervals the driver will be required to provide additional breath samples, to prevent them from having another individual provide the initial sample to start the vehicle.

In Tennessee, if you have been convicted of a DUI, and have requested a restricted license that would allow you to drive to a job, if you will likely be required to have a ignition interlock device installed as a condition of your probation.

You will have to maintain the device for the one year if you were sentenced to a first offense, and you will need to keep in place for an additional six month after your probation ends.

You are only permitted to operate the vehicle with the interlock installed and the length of your revocation period grows with each conviction. With a fourth conviction, if you are able to obtain probation at all, you would have to maintain an interlock device for eight years and six months., “State Ignition Interlock Law,” Updated August 2014

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