What Is An Ignition Interlock Device?

If you have been convicted of DWI or intoxication assault, you may have a court order to install an ignition interlock device in your vehicle.

How does the device work?

What Is An Ignition Interlock DeviceAn ignition interlock device (IID) is essentially a breathalyzer installed in your vehicle. These can be required for a mandatory amount of time following a DWI conviction.

The IID connects directly to your car’s ignition. In order for the car to start, you must pass a breath test to determine that you have no alcohol in your system. If the device detects the presence of alcohol, it will not start.


You must blow into the IID each time you start your vehicle. It will also prompt you to take the test while you are driving.

Texas IID Laws

Each state has laws regarding IID penalties. In Texas, ignition interlock devices are a required punishment for each second and subsequent DWI conviction. They are also required for anyone who is convicted of DWI after testing at a .15% BAC or higher.


In some cases, an IID is required when the individual is let out on bond. This means that while the case is being handled, the driver accused of DWI will have to use the IID.If the driver is mandated to use an IID during probation, it must be used for at least half of the probation period.

Qualifying for an IID

If you currently have a suspended license due to DWI, you may be able to apply for the IID program. The installation of an IID would allow you to be able to drive again.

To be eligible:

  • You must have a valid Texas driver’s license
  • The license suspension must not be due to a reason other than DWI
  • You must not have outstanding fines on your driving record

If you believe you may be eligible for a restricted interlock license, we can help. At Deandra Grant Law, we have over 25 years of experience with numerous types of DWI cases. Contact us today to set up a consultation with one of our Dallas DWI attorneys.

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