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Ignition Interlock Devices

Driving while intoxicated (DWI) is a unique charge because it incorporates a lot of sentencing conditions. One of these is the possibility that you may be required to install ignition interlock device (IID). If you are a repeat DWI offender, then it’s likely the judge will order you to install an IID.

An ignition interlock device is similar to a breathalyzer, but it’s linked to your car engine. The device requires you to submit a breath sample before starting the car. The purpose of an IID is to deter DWI offenders from driving drunk again. If the device calibrates a BAC of .08, then the car engine will be locked.

Ignition interlock devices are a hassle and can be expensive. You’ll also be required to pay the installation and monthly costs of your IID. Because of this, it’s important you visit this article, so you’re prepared for what’s next.

DWI Attorney for IIDs in Houston, Texas

An ignition interlock device can limit you incredibly. The instrument itself isn’t always accurate and can give false readings. This means your car could be unusable at any time if the device malfunctions. In addition, the costs of an IID can really hurt your wallet.

Avoid this entirely with a strong defense with Flood Lewis & Associates, Inc.. Our attorneys at Flood Lewis & Associates, Inc. have a primary focus in DWI law. We can utilize our skills to create a strong defense for you, so you can avoid an IID installation. Call us now at (713) 224-5529 to schedule a free consultation today.

Flood Lewis & Associates, Inc. accepts clients throughout the Harris County area including Houston, Pasadena, Tomball, Bellaire and West University Place.

Overview of Ignition Interlock Devices in Texas


Texas DWI Laws Concerning IIDs

Texas has established DWI laws regarding ignition interlock devices under the Transportation Code and Penal Code. The majority of first-time DWI offenders will not require an IID. The courts typically take first-time DWI charges as an uncharacteristic lapse of judgement from the defendant. If you’re a repeat DWI offender, then it’s a different story.

Texas Penal Code § 49.04(h) states you’re required to install an ignition interlock device if you have a second or subsequent DWI within five years of your first offense. The device will be installed on every operable motor vehicle you own, and you must pay for the entire cost yourself. You’ll be prohibited from driving any vehicle without an IID attached.

Previous DWI offenses cannot be used as a prior conviction if:

  • The prior conviction was committed more than 10 years before; and
  • You haven’t been charged with DWI within 10 years of your first conviction and the date of your current DWI charges

The court requires you to install an IID before the first anniversary of your license suspension. The Texas Department of Public Transportation (DPS) will bar you from obtaining a license until you’ve installed your IID. You are, however, entitled to an occupational license without finding an essential need if you installed your IID in a timely manner.

You might be able to drive a motor vehicle without an IID if:

  • The vehicle you use is for your job;
  • Your employer owns the vehicle;
  • You don’t control or have authority over your employer in any way;
  • Your employer was notified of your driving restrictions; and
  • There is proof of that notification in the vehicle

Aggravated DWI cases may also require an IID installation. Circumstances such as having a child passenger or a blood-alcohol concentration (BAC) of .15 will turn your DWI into an aggravated DWI. If you’re charged with an aggravated DWI, it’s likely the judge will impose an ignition interlock requirement on your sentencing.


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What is an Ignition Interlock Device?

An ignition interlock device is basically a breathalyzer installed in your car. The instrument is also attached to your engine. Once installed, you’ll be required to submit a breath sample if you want to start the car. If you have a BAC of .08 or higher, then the engine will lock from use.

Texas adopted IID laws in attempt to deter multiple DWI offenders. The car will be basically unusable until the IID measures a BAC under the legal limit. If you blow at or over .08, then the device will log the event internally. Multiple failed breath tests could result in the device notifying your local authorities.

There’s no way to “cheat” an IID either. The device requires rolling-retests, which are random breath tests while you’re driving. This is to stop others from blowing for you. If your IID detects a high BAC during a rolling re-test, it’ll not turn off the engine. Instead it will flash the lights and honk the horn excessively until you’ve turned off the vehicle.


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How Much Does an Interlock Device Cost in Texas?

Ignition interlock devices aren’t just a hassle, they’re expensive. The court requires you to pay the full installation and monthly cost of an IID. It can be incredibly costly because it requires a deposit, monthly calibration costs, and the initial installation. In some cases, the court will create a reasonable pay schedule to assist with the expenses.

Ignition interlock devices are installed by third-party companies. This means you do have some choice in where your IID comes from. However, you cannot simply find a “cheap” IID company. The IID must meet the requirements listed out in Texas Transportation Code § 521.2476.  Because of this, the majority of companies have similar pricing.

IID installation companies usually require information on your case to give you a quote on the possible pricing. Some companies even offer payment plans if you’re economically struggling. The general costs for an IID and installation include:

  • $70$100 for installation;
  • $60$80 for monthly calibration costs;
  • $100 for a refundable deposit; and
  • Possibly monthly insurance charges

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Additional Resources

IID Laws in Texas – Visit the official website of Texas Transportation Code to learn more about laws surrounding ignition interlock devices. Access the statute to learn requirements for IID vendors, how long an IID is required and how it applies to restricted licenses.

Ignition Interlock Devices – Visit the official website of the Texas Department of Public Safety (DPS) to learn more about IID. Access the site to find more information about required fees, what happens to your license and where to submit IID compliance documents.


DWI Lawyer for IID in Harris County, Texas

If you or someone you know has been charged with DWI, it’s crucial you gain legal counsel. You could possibly face serious consequences including fines and even incarceration. Additionally, you could be saddled with an ignition interlock device, which can restrict you even more.

Call Flood Lewis & Associates, Inc. to speak to an experienced criminal defense attorney. We understand the ins and outs of DWI law in Texas.  Our attorneys can evaluate your charges and chart out a defense plan that works for you. Contact us by phone at (713) 224-5529 to schedule a free consultation.

Flood Lewis & Associates, Inc. represents clients throughout the Houston metroplex area including Pasadena, West University Place, Tomball and River Oaks.



This article was last updated on March 11th, 2019.

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