How Ignition Interlock Devices Work in Texas

 Posted on April 05,2017 in DWI / DUI

Texas Requiring DWI Offenders to Use Ignition Interlock DevicesSince 2015, Texas law has required many people convicted of driving while intoxicated to use ignition interlock devices on their vehicles as a condition of restoring their driving privileges. The new program is meant to reduce incidents of intoxicated driving by previous offenders and provide some first-time offenders an alternative to a suspended driver’s license. Mothers Against Drunk Driving, an organization that advocated for the law, claims that the number of drunk driving deaths in Texas have decreased by 8.5 percent since the law was passed. Because of the newness of the law, it is difficult to find a comprehensive source clearly explaining the ignition interlock device program. Here are the answers to some basic questions.

What Is It?

An ignition interlock device is a small breathalyzer connected to a vehicle’s ignition system and typically located on the vehicle’s passenger side. Before starting the vehicle, the driver must breath into the device. If the breath alcohol content is greater than a preset limit, then the vehicle will not start. After a vehicle is started, the device will sometimes require the driver to provide an additional breath sample to prove continued sobriety. The driver will be alerted of the retest and given time to pullover to a safe location before providing another sample.

Who Gets One?

Whether a court requires an ignition interlock device depends on the severity of the offense.

  • For first-time DWI convictions with a blood alcohol content less than 0.15, offenders can choose either a suspended driver’s license (which can last for 90 days to one year) or having an ignition interlock device installed on their vehicles.
  • If it is a second DWI offense or the first-time offender had a 0.15 or greater BAC, the offender’s driver’s license will be suspended. After the license is reinstated, the offender will be required to use an ignition interlock device for a year.

What Does It Cost?

The Texas Department of Motor Vehicles charges a $10 license fee to register as an ignition interlock device user. However, the main costs come from the installation and maintenance of the device. The state has a list of certified private installers, so users can shop around for the best deal. Estimates show installation can cost $70 to $150, and monitoring and calibration fees can cost $60 to $80 per month.

Facing DWI Charges

An ignition interlock device is another penalty that can come with a DWI conviction. An experienced San Antonio DWI defense lawyer at the Law Offices of Samuel H. Lock will work to prevent your conviction. Schedule your appointment by calling 210-226-0965.


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Bexar County

In the historic King William District

1011 S. Alamo,
San Antonio, Texas 78210