Most people think DWI means "over 0.08." That is half of the definition — and the half the State relies on less often than you would think. Brian Foley explains in this video.
Penal Code § 49.01(2)
"Intoxicated" means:
(A) not having the normal use of mental or physical faculties by reason of the introduction of alcohol, a controlled substance, a drug, a dangerous drug, a combination of two or more of those substances, or any other substance into the body; or
(B) having an alcohol concentration of 0.08 or more.
Prong A — "loss of normal use"
This is the prong that makes DWI possible with no test at all, with a test under 0.08, and with drugs — prescription, illegal, or otherwise. The State proves it through the officer's observations, the field sobriety tests, the in-car video, and statements. The defense attacks it the same way: the video showing a coherent, steady driver; the sobriety tests improperly administered; the "normal" being judged by an officer who never saw you sober. In prescription drug DWI cases, the State must also prove the drug caused the impairment — which requires more than a pill bottle.
Prong B — 0.08
An alcohol concentration of 0.08 or more in breath, blood, or urine at the time of driving. Because tests are taken later, the State either argues the number speaks for itself or calls an expert to extrapolate backward. The defense attacks the breath machine, the blood draw and lab, and the extrapolation's assumptions. A 0.15 or more enhances a first DWI to a Class A misdemeanor.
Why both matter
The jury is instructed on both prongs and can convict on either. A driver with a 0.07 blood result can be convicted under prong A if the video looks bad. A driver with a 0.12 can be acquitted if the jury doubts the number and the video looks fine. That is why every DWI defense is built around the video first.
See our Houston DWI attorney page or call or text (713) 703-1718 for a free consultation.