The Importance of Breathalyzer Test Accuracy in DWI Cases in Missouri City

The Importance of Breathalyzer Test Accuracy in DWI Cases in Missouri City
Jun 06, 2025 |

Being pulled over or arrested on suspicion of driving while intoxicated (DWI) can be incredibly stressful. It is even more so when the field or station breath test claims you were over the legal limit. It’s important to understand that the breathalyzer test accuracy in DWI cases in Missouri City is not always perfect. Actually, there are numerous ways that breath tests can be mistaken, whether due to improper calibration, the misadministration of the test, or other conditions.

While not all breathalyzer results can be challenged, some may. This is a crucial piece of evidence in your DWI case, so it’s important to determine if the evidence is sound.

Types of Breath Tests

It is crucial to understand the difference between a breath test given when you are pulled over and the breath test at the police station.

A preliminary breath test (PBT) is one that may be given when you are first pulled over, alongside other field sobriety tests. The PBT is a portable breathalyzer. It tests the alcohol concentration in your breath when the officer has grounds to believe you are driving while intoxicated. These machines are especially vulnerable to miscalibration and inaccuracy. Their results are often grounds for probable cause of arrest, but they are rarely admissible evidence in court.

When you are arrested, you will have to take another breath test at the police station. This is a chemical test through a breathalyzer. In Texas, the Intoxilyzer 9000 is the permanent breathalyzer used to test alcohol in your breath sample.

These machines are much less likely to be miscalibrated or inaccurate, and a test result over the legal limit will be strong and admissible evidence against you. The Texas Administrative Code lists the Texas Breath Alcohol Testing Regulations, which outline the requirements for breath tests and analysis. They also outline the calibration requirements for these devices.

There are more than 370 testing facilities in the state approved to conduct these analyses using the Intoxilyzer 9000. The Missouri City Police Department is at 3849 Cartwright Road.

What Are Common Reasons to Challenge PBT and Breathalyzer Results?

While permanent breathalyzers are more reliable than a PBT, there may be issues with either machine. If one of these problems were present, the evidence could be challenged, making it harder or impossible to convict someone of a DWI.

Some of the most common ways to contest a breath test result include the following:

  1. The device was miscalibrated or improperly maintained: Without regular calibration, the readings can be incredibly inaccurate. It’s important to review the calibration notes of the specific machine.
  2. There was an operator error: There are 6,000 certified operators of breathalyzer machines in Texas. The competence and abilities of the operator are crucial for an accurate test from either a PBT or a breathalyzer test. Poor timing, mishandling, failing to follow instructions, or other issues can render the results incorrect.
  3. Violations of an individual’s rights: Officers should read a suspect their rights prior to a breathalyzer test. Failure to do so is a rights violation and could result in the evidence being inadmissible.
  4. Environmental factors: A person’s diet, medical conditions, medication, and other factors can cause a false positive in a breathalyzer or PBT.
  5. Evidence contamination: If the evidence is mishandled, contaminated, or fails to follow the appropriate chain of custody, it could be inadmissible.

Discuss Your DWI Case With Skilled Attorneys in Missouri City

Over 37% of vehicle collisions involved impaired drivers in Texas from 2014 to 2023. The state prosecutes these cases harshly. Contact Segura & Kiatta today to learn how our DWI attorneys can challenge the evidence and potentially avoid a conviction.

Contact us

Contact segura & kiatta criminal defense

Schedule Your
Free Consultation

*Required Information

(Required)
This field is for validation purposes and should be left unchanged.

Our Location

Segura & Kiatta, Criminal Defense
345 Commerce Green Blvd
Suite 200
Sugar Land, Texas 77478