Ignition Interlock Devices: An Overview

Ignition interlock devices (IID) are often ordered as part of sentencing for DWI charges in Texas. When installed, the device prevents an individual from operating their vehicle if their breath registers the presence of alcohol. The driver must blow into a breath machine to start the vehicle, and after driving for a few minutes they are required to submit another breath sample in order to keep the vehicle running. IIDs are designed to reduce the number of DWI/DUI incidents per year.

In general, IIDs are installed in the vehicles of people who have been convicted of multiple DWI offenses. Unless a plea bargain is reached or other circumstances lead to reduced penalties, even a second conviction can result in the mandatory installation of an IID. While these devices are helpful in keeping a person from driving while intoxicated, there are a number of unfortunate side effects of having an IID installed.

Costs of an IID

First, an IID can cost a significant amount of money. In addition to an initial installation fee, you will have to make monthly payments to rent out the mandatory device. Beyond this, you will have to install the device on all of your vehicles, possibly meaning increased payments for multiple IIDs.

Shared Vehicles

In addition to the cost of the device, an IID will affect all other people who use your vehicles. Anyone who shares your vehicle will also have to use an IID, leading to a greater hassle for them and possibly affecting you if they get behind the wheel after drinking.

False Test Results

IIDs are designed in such a way that it is very difficult to fake sobriety while a device is installed in your vehicle. Unfortunately, it is not so difficult to produce false results of intoxication. If you have eaten certain foods containing yeast, taken certain medicines, or used mouthwash, you may be unable to start your car. This “violation” may show up in your report later.


If you would like to learn more about IIDs, contact a Dallas DWI defense attorney from The Wilder Firm. In addition to answering your questions, we can provide top-quality legal representation as you seek to fight your charges and reduce/eliminate your sentencing. Contact The Wilder Firm today to schedule a free case evaluation with our proven DWI defense team.