Louisiana DWI breath-test evidence and foundation
Audit the instrument, operator, observation period, sequence, raw record, maintenance, and competing explanations before drawing conclusions.
Source review: October 16, 2026What this pathway evaluates
A reported breath result should be tied to the correct person, instrument, operator, date, time, test sequence, certification, and applicable method. The printed ticket alone may not answer every foundation or reliability question.
The review should distinguish a statutory concentration theory from an impairment theory. A successful challenge to one item may still leave driving evidence, observations, statements, refusal evidence, or another chemical sample.
Possible interference claims—such as residual mouth alcohol, reflux, regurgitation, an oral product, or a metabolic condition—must fit the actual device, timing, safeguards, records, and scientific evidence. A diagnosis or symptom list by itself does not establish an invalid result.
Issue map
Identity and sequence
Match subject, operator, instrument serial number, location, test time, arrest time, samples, error messages, duplicate results, and every printed or electronic record.
Instrument and operator
Request the records relevant to approval, certification, maintenance, inspection, repair, software or configuration, simulator or reference checks, operator qualification, and the method used.
Safeguards and observations
Use video and logs to test the claimed observation period, ingestion, smoking, regurgitation, foreign substances, device prompts, retesting, and operator response.
Expert fit
A technical opinion should identify the data reviewed, reliable method, error or interference mechanism, magnitude, and incident-specific fit. General possibilities are vulnerable to exclusion or little weight.
Questions this route should answer
Is every 0.08 result automatically admissible and correct?
No result is self-authenticating in every respect. Foundation, procedure, identity, reliability, and admissibility are evaluated from the actual record and governing law.
Does an equipment issue automatically dismiss the charge?
No. The issue must be proved, connected to the reported result, and tied to an available legal remedy. The State may rely on other evidence or theories.
Can reflux or mouth alcohol matter?
Potentially, but only when the condition, event timing, device safeguards, video, raw data, and qualified scientific explanation support incident-specific relevance.
Primary sources
These links are starting points, not a substitute for reading the current law, court orders, and the complete record.