Law enforcement uses different types of chemical testing to measure your impairment level. The most common chemical test is breath analysis, which is commonly used with a breathalyzer or intoxilyzer. A breathalyzer or intoxilyzer determines your blood-alcohol concentration (BAC) with a breath sample.

Breathalyzers measure the amount of alcohol in your breath using a specialized reactive mixture. This mixture is made with certain chemicals that can detect gas such as vaporized ethanol. If the machine isn’t calibrated correctly, then the results could be skewed. Other external factors can also disrupt a breathalyzer’s readings including slow metabolisms, dieting and even the temperature of your breath.

If you or someone you know has undergone a breath test, it’s imperative you contact a skilled DWI attorney.

Attorney for Breathalyzer Tests in Houston, Texas

Police officers heavily rely on breath analysis when making a DWI stop. However, breathalyzers or intoxilyzers can generate false results because of a variety of factors. If you or someone you know has failed a breath analysis test, it’s imperative you contact an experienced criminal defense attorney.

Contact the attorneys at Tyler Flood & Associates, Inc. for skilled legal representation. The attorneys at Tyler Flood & Associates, Inc. have years of experience handling DWI cases. Tyler Flood, our managing attorney, has been designated as an ACS-CHAL Lawyer-Scientist. This means he has an in-depth understanding of the science behind DWI testing. He can analyze your case to spot any errors with your test results.

Call us now at (713) 224-5529 for a free consultation. We accept clients throughout the greater Harris County area including Pasadena, River Oaks, Bellaire and Houston.

Overview of Breathalyzer in Texas

How Does a Breathalyzer or Intoxilyzer Work?

Breathalyzers and intoxilyzers measure the amount of alcohol in your breath. Police officers tend to have two types of breathalyzers depending on the situation. Small portable breathalyzers are given to officers for individual use. However, they’re known to give unreliable readings so often not used in court.  Law enforcement also uses larger breathalyzers or intoxilyzers found in police stations. These devices give much more accurate results than their portable counter parts.


Breathalyzers and intoxilyzers both measure alcohol-concentration, but function differently. A breathalyzer is made up of two glass vials which contain a chemical reaction mixture and a system of photocells connected to a meter. The meter measures color changes associated with a chemical reaction.

To calculate BAC, you must breathe into the device. The breathalyzer will then process the sample through a mixture of chemicals including sulfuric acid, potassium, dichromate, silver nitrate and water. If there’s alcohol in your system, then the reddish-orange mixture will change to a green. Law enforcement will then compare the tested reacted mixture with an unreacted mixture. After this, they will have a blood-alcohol concentration (BAC) reading.

Hand-held breathalyzers use the same principle as a full-sized device. However, they are much more susceptible to errors than a standard breathalyzer. Because of this, the prosecution typically relies on full-sized device readings instead of portable breath tests.

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Intoxilyzers uses infrared (IR) spectroscopy, which identifies molecules on how they absorb IR light. The device can do this because atom molecules react differently when they absorb IR light. You can identify ethanol in a breath sample by reading a molecule’s wavelength bonds.

An intoxilyzer uses a lamp to generate an IR beam.  The IR beam phases through the sample chamber and then a lens focuses the sample onto a spinning filter wheel. The wheel has narrow band filters that are designed to match the wavelengths of ethanol bonds. The IR beam passes through the filter wheel and is then converted into an electrical pulse. The pulse is then relayed to a microprocessor where a BAC is determined based on the absorption of infrared light.

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Can a Breathalyzer or Intoxilyzer Be Wrong?

Since officers heavily rely on breathalyzers or intoxilyzers, you might assume breath analysis is an accurate process. Unfortunately, this cannot be farther from the truth. Breathalyzers and intoxilyzers can give false results because of external factors such as metabolism or diet.

Breathalyzers and intoxilyzers must also be maintained regularly. If the equipment isn’t calibrated or maintained, then the device may give skewed results. Lab technicians and police officers must also be careful when administering a sample. If the sample is contaminated, then the instrument may give a false reading.

Listed below are some common problems that occur in breath analysis.

  • The device wasn’t calibrated properly;
  • You belched, vomited or hiccuped right before the test;
  • You’re on a diet;
  • There are still traces of alcohol in your mouth;
  • You have a slow metabolism;
  • The temperature of your breath;
  • You have diabetes;
  • Electromagnetic interference with the device such as cellphone signals;
  • You have acid reflux;
  • The officer read the results wrong;
  • You took cold medicine;
  • You work with paint, lacquer, cleaning solvents or other alcohols; or
  • The officer didn’t follow procedures

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Should I Refuse a Breathlyzer or Intoxilyzer Test?

A common question asked to attorneys is if you should refuse a breath test or not. While the answer is ultimately up to you, it’s safe to say the majority of lawyers would say yes. You can choose to submit to breath analysis if you’re very confident you’ll have a low BAC. However, it’s been reported that perfectly sober people have failed breathalyzer tests due to other factors.

The many risks of a breathalyzer or intoxilyzer test might not be worth the chance. If you blow a BAC over .08, then you’ll automatically be arrested for driving while intoxicated (DWI). You’ll face an administrative license suspension for up to six months. In addition, the prosecution will have concrete scientific evidence of your DWI during trial.

Because of this, many attorneys will advise you to refuse a breathalyzer test. You have this right despite implied consent laws. Implied consent laws state you’re implicitly agreeing to chemical testing if you drive on public roads.

Violating these laws will result only in an administrative license suspension for up to 180 days. A second refusal can result in a two-year license suspension.

A suspended license is a hassle, but it’s much easier to handle than a DWI conviction. You can choose to contest this suspension with an administrative license revocation hearing. However, you must act quickly. You only have 15 days to file a request an administrative license revocation (ALR) hearing. If you and your attorney are successful at the hearing, then you can continue using your license.

It’s important to know you could be arrested for refusing a breath test. If your arresting officer has probable cause you’re intoxicated, then they can arrest you without a BAC reading. An arrest is stressful, but it’s only a temporary process. Once you’re released the prosecution won’t have any hard evidence against you. It’ll be much more difficult for the prosecution to convict you without your BAC results.

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Additional Resources

Texas Breathalyzer Manual – Visit the official website of the Texas Department of Public Safety (DPS) to learn more about breath analysis. Access the document to learn the history, procedures and maintenance of both intoxillyzers and breathalyzers.

Texas Implied Consent Laws – Visit the official website of Texas Penal Code to access the statutes surrounding implied consent laws. Access the statute to learn more about the penalties for refusal, what happens if someone is incapable of refusal and required information provided by the officer.

Lawyer for DUI Breathalyzer Test in Harris County

If you or someone you know has been charged with DWI, then it’s crucial you gained legal representation. A skilled attorney can assess your breath analysis results for any errors. They can also formulate a strong defense for you in court.

Call Tyler Flood & Associates, Inc. today to speak to an experienced DWI attorney. Our attorneys are passionate about criminal defense and want to use our skills to help you. Contact us today at (713) 224-5529 to schedule a free consultation. We accept clients throughout the greater Houston area and surrounding communities including Bellaire, Tomball and River Oaks.

This article was last updated on March 7th, 2019.


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Robert Henderson
Robert Henderson
December 22, 2023.
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briana Munoz
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October 12, 2023.
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Cesar Ricardez
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