Rising BAC in Texas DWI Cases: Collection Time, Driving Evidence and Expert Limits

Collection time and driving time are different facts

An alcohol result reflects a specimen obtained at a particular time. Relating it to driving may require attention to the timeline, the person’s drinking history and the other evidence. A delay alone does not establish whether concentration was rising, falling or similar.

A specimen collection time is also different from the later date a laboratory analyzes a stored sample. Do not treat laboratory turnaround time as extra absorption time in the person’s body.

Do not equate below 0.08 with automatically sober

Texas Penal Code Section 49.01 includes loss of normal mental or physical faculties as an alternative definition of intoxication. A proposed estimate below 0.08 therefore does not, by itself, resolve every DWI allegation.

Food and drinking patterns may be relevant, but they do not prove a particular person was unimpaired. Do not use a universal absorption delay, elimination rate or a generic online BAC curve to reconstruct an individual case.

Mata and Stewart answer different questions

Mata evaluates the reliability of retrograde extrapolation, an estimate of an earlier alcohol concentration. Its analysis considers the circumstances, the testing and information available to the expert; it is not a mechanical rule requiring every possible personal fact in every case.

Stewart rejects the proposition that later breath results are necessarily irrelevant without retrograde extrapolation. A result may be considered with other evidence even when a precise earlier BAC cannot be reliably calculated. Relevance and conclusive proof are different standards.

Build the timeline without filling gaps

Identify the last known operation, stop, observations, specimen collection and testing records. Tell counsel accurately what you remember about food and drinks, and keep uncertainty explicit. Preserve existing receipts or other records lawfully available.

Ask what assumptions support any expert opinion and what information is missing. A possible rising-BAC explanation is a hypothesis to evaluate, not a guarantee that an admissible test will be excluded or that the case will be dismissed.

Questions and records to compare

Question	Useful record	Limit to remember
What time was driving?	Video, witnesses and recorded events	Do not invent an exact time from a vague memory
When was the sample collected?	Collection documentation	Analysis date is not collection time
Can an earlier level be estimated?	Expert basis and relevant history	A generic curve is not a personal measurement
What other evidence exists?	Driving, observations and recordings	A proposed level below 0.08 does not settle faculties

What to bring

• Actual test and collection records already received

• Charging and bond paperwork

• Accurate remembered food and drink timeline

• Existing receipts, messages or location records for counsel

• Questions about any expert assumptions

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.

• 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.

• Mata v. State, 46 S.W.3d 902 (Tex. Crim. App. 2001) — Primary court opinion reviewed October 20, 2026. Reliability of retrograde extrapolation depends on the circumstances and information; not a rule requiring every possible personal fact in every case.

• Stewart v. State, 129 S.W.3d 93 (Tex. Crim. App. 2004) — Substituted primary opinion: later breath results may be relevant without retrograde extrapolation; relevance, reliability and sufficiency are different questions.