Portable Breath Tests in Texas DWI Cases: Screening, Numbers and Trial Evidence

Identify the device before interpreting the result

A handheld preliminary breath test, or PBT, is used during roadside screening. Do not assume it has the same purpose, approval or procedures as an evidentiary breath test. Identify the model, the operator and when the sample was obtained before interpreting what the result can establish.

NHTSA describes both uses and limitations of preliminary breath testing. It discusses mouth alcohol, contaminants, sample conditions and radio interference as potential concerns. The existence of a possible interference does not establish that it affected a particular result.

Presence of alcohol and a numerical concentration are different uses

Evidence suggesting alcohol was present is different from evidence offered to establish a precise concentration. A legal review should identify exactly what testimony or number is proposed, the purpose for which it is offered and the foundation supporting it.

Do not treat every roadside result as automatically admissible or automatically excluded for every purpose. Device-specific evidence, the governing Texas rules and the procedural setting matter. A ruling about one use does not necessarily answer another.

No later chemical result does not mean no DWI evidence

The State can allege intoxication through loss of normal mental or physical faculties, not only through an alcohol concentration of 0.08 or more. Driving observations, recordings and other admissible evidence can remain important even if a numerical result is disputed.

Taking a roadside screening test also does not resolve a later request for an official specimen. Review the warnings, request, response and any warrant separately. Do not assume the first test settles the later license or criminal issues.

Build a record-based review

Locate the video showing the device and instructions, the report and any printed results. Ask which device records are needed and which evidence the State intends to use. Compare that information with the legal basis for any proposed objection.

An objection to a number is not a promise that the arrest was unlawful, that every observation disappears or that the prosecution must dismiss the case.

Questions and records to compare

Question	Useful record	Limit to remember
Which device?	Video, report and model identification	Handheld does not identify every approval or use
What is being offered?	Proposed testimony and result	Presence and numerical concentration differ
What else exists?	Driving video, observations, later testing	A disputed result is not the whole case

What to bring

• Charging and bond paperwork

• Any roadside or station result already received

• DPS notices and envelopes

• Your accurate recollection of the testing sequence

• Questions about the device and proposed evidence

Bring what you already have. Ask your lawyer about obtaining missing material, and do not post private case details in public comments.

Questions about your Houston DWI case?

To discuss representation, call Ruben Restrepo at 713-714-7330 or contact the office. Learn more about our Houston DWI practice.

Sources and review

Reviewed October 20, 2026. General information; the facts, applicable law, notices and orders in an individual case matter.

• NHTSA/IACP — 2023 SFST Participant Manual — Revised February 2023. Local primary PDF reviewed: Session 7, pp. 18–23 / PDF pp. 203–208 (PBT); Session 8, p. 16 / PDF p. 229 (optokinetic nystagmus). Training guidance is not a Texas exclusion rule.

• Texas Penal Code Chapter 49 — Current legislative text reviewed October 20, 2026. Sections 49.01, 49.04, 49.045, 49.07 and 49.09; apply the provisions and effective dates relevant to the alleged offense.