Roadside Breath Tests vs. Jail Breathalyzers: What’s Inadmissible in Court?
In Texas, breath alcohol testing plays a central role in many Driving While Intoxicated (DWI) investigations. But not all breath tests are treated equally in court. If you were stopped on suspicion of DWI and asked to blow into a device on the side of the road, you might wonder: Will that roadside breath test be used against me in court?
The answer: Probably not. Here’s why.
Understanding the Two Types of Breath Tests in Texas
When someone is suspected of DWI in Texas, law enforcement may use two types of breath testing devices:
1. Preliminary Breath Test (PBT) — Used at the roadside
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Often handheld devices
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Administered during a traffic stop
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Used to help officers establish probable cause for arrest
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Not admissible in court for proving actual intoxication
2. Evidential Breath Test (EBT) — Administered at the jail or police station
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Performed on a machine like the Intoxilyzer 9000
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Maintained and calibrated under Texas Department of Public Safety (DPS) guidelines
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Admissible in court as evidence of intoxication (if properly administered)
Why Are Roadside Breath Tests Inadmissible?
Texas courts generally do not allow preliminary breath test results to be presented as evidence of intoxication at trial. Here’s why:
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Lack of Reliability: PBT devices are not held to the same strict calibration and maintenance standards as evidential machines.
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No DPS Approval: These handheld devices are not approved by the Texas DPS for evidentiary use.
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Probable Cause Tool Only: The law treats roadside tests as tools to justify arrest — not as definitive proof of guilt.
Texas Case Law Insight: Courts in Texas have routinely excluded PBT results under Rule 403 of the Texas Rules of Evidence — stating that the potential for unfair prejudice outweighs the test’s probative value.
When Can Breath Test Results Be Used in Court?
To be used in a DWI trial, a breath test result must come from an approved evidentiary device, and it must be:
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Administered by a certified breath test operator
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Performed using a machine that is regularly calibrated and maintained
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Conducted within a specific timeframe after the arrest to ensure accuracy
If these conditions aren’t met, the defense may be able to suppress the test results through a motion in limine or pretrial hearing.
Key Takeaways
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Roadside breath tests (PBTs) are primarily used to establish probable cause, but are not admissible in court to prove intoxication.
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Jail-administered breath tests using approved machines like the Intoxilyzer 9000 can be admitted in court, but only if specific procedural safeguards are followed.
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Criminal Defense attorneys often challenge the validity and admissibility of breath test results based on device maintenance, operator certification, and procedural errors.
Why This Matters
Understanding the distinction between roadside and evidentiary breath tests can help individuals make informed decisions if they’re ever stopped or arrested for DWI. It also underscores the importance of protecting legal rights during the investigative and trial process.
Cheryl A. Wulf, Attorney at Law
Office: 11702 State Hwy 64 E, Tyler, TX 75707
Call: (903) 525-9869
Fax: (866) 824-4469.
