Ask Deandra: Can I Be Arrested for DWI in Texas if I’m Under 0.08?

Here is the longer answer: what the statute actually says, how the loss-of-faculties standard works, what a sub-0.08 result does and does not do to your license, and why a low reading does not end a DWI investigation in Texas.

The Texas Definition of Intoxication

Texas Penal Code §49.01(2) defines “intoxicated” in two ways. A person is intoxicated if they:

• (A) do not have 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) have an alcohol concentration of 0.08 or more.

Both definitions are independently sufficient. The State does not have to prove both. The State has to prove either one. That structure is the key to understanding how a person can be arrested and prosecuted for DWI even with a BAC under 0.08.

The 0.08 prong, known as the per se prong, is the one most people know about. The loss of mental or physical faculties is the other prong. Both have been part of Texas DWI law for decades. Both are charged regularly.

Two features of that structure are worth understanding:

• The jury does not have to agree on which prong. The Court of Criminal Appeals has described the two definitions as alternate means by which the State may prove intoxication rather than alternate ways of committing the offense. The conduct the law forbids is driving while in a state of intoxication, and that does not change depending on which definition the State uses. So where both theories are submitted, some jurors can convict on the number and others on the observations, and the verdict stands.
• A test result by itself is not enough for the number theory. The State has to connect the result back to the time of driving, not the time of testing. That requires either retrograde extrapolation testimony or other evidence supporting an inference that the person was intoxicated when they drove. This is the whole basis of the rising blood alcohol defense, and it is also why the State so often falls back on the impairment prong when the timing gets difficult.

One more piece of the statute worth knowing, since this post is about a number that is not as protective as people think. There is a second number running the other way. Under Penal Code §49.04(d), a first DWI becomes a Class A misdemeanor when the analysis shows 0.15 or more, which roughly doubles the exposure. And driving while intoxicated requires operation in a public place, which is an element the State has to prove like any other.

How an Under-0.08 Arrest Actually Happens

Several common scenarios produce a DWI arrest with a BAC below 0.08:

• Low-BAC arrest based on roadside performance. A driver blows a 0.06 on a portable breath test, which is a screening device rather than the instrument used at the station, performs poorly on field sobriety tests, and the officer arrests on the loss-of-faculties theory. The lab confirms the sub-0.08 result, and the case proceeds on the impairment prong.
• Drug-only DWI. A driver who has used cannabis, prescription medication, or any other substance can be charged with DWI even with a BAC of 0.00. Texas has no per se drug limit, so the entire prosecution rests on the loss-of-faculties theory.
• Combination cases. A driver who has consumed alcohol and a drug, even a legal one, may have a low BAC but be charged on the theory that the combination produced loss of faculties.
• Refusal cases without test results. If a driver refuses a breath or blood test and the State cannot obtain a warrant, there may be no chemical evidence at all. The case proceeds entirely on observational and behavioral evidence under the loss-of-faculties theory.
• Rising-BAC cases. Where the BAC at the time of the test is above 0.08 but the defense can argue the BAC was lower at the time of driving, the State may shift to the loss-of-faculties theory to avoid the timing problem.

In all of these scenarios, the absence of a 0.08 reading does not protect the defendant. There is a Texas case in which a driver blew “0.00” on the breath test and a magistrate still found probable cause to sign a blood warrant, based on the driving, an admission to drinking, and the officer’s observations. The court noted that a breath test is not an infallible measure. If you are reading this because you blew low and were arrested anyway, that is the posture you are in, and it is a normal one.

What a Sub-0.08 Result Means for Your License

This is the part almost nobody explains, and for many readers it is the best news on the page. The criminal case and the license case run on separate tracks with separate rules, and a low result affects them very differently.

• If you are 21 or over and you gave a sample that came back under 0.08, there is no failure suspension. The statute is explicit: the department may not suspend where an adult’s specimen shows an alcohol concentration below the level in the Penal Code definition. So the administrative case that would otherwise follow a test result does not exist. The criminal case can still go forward on the impairment prong, but the license side of it is closed.
• That protection depends on your having given a sample. If you refused, the failure track never opens and the refusal track does, and it is worse. A refusal carries a 180-day suspension, rising to two years if you have an alcohol-related or drug-related enforcement contact in the preceding ten years. Compare that with the 90-day suspension that follows a failed test. Refusing is the longer road on the license side even though it may be the better decision on the criminal side, which is exactly why the two decisions need to be thought about separately.
• If you are under 21, the 0.08 threshold does not apply to your license at all. Any detectable amount of alcohol supports a suspension, starting at 60 days for a minor with no prior, then 120 and 180 days. See the section on under-21 drivers below.

None of this happens automatically in your favor. You have fifteen days from the date you are served with the notice of suspension to request the hearing, and if you miss that deadline the suspension takes effect by default no matter what your reading was.

What “Loss of Normal Use of Faculties” Actually Means

The phrase is intentionally broad. Texas courts have not defined it as a precise medical or scientific concept. It is a question for the jury, given general guidance about the ordinary meaning of the words. “Mental faculties” refers to the ability to think, perceive, judge, and react. “Physical faculties” refers to the ability to control the body: balance, coordination, motor function, speech.

In practice, the State proves loss of faculties through:

• Driving behavior. Weaving, speeding or excessively slow driving, failure to maintain a lane, missing a stop sign, hitting a curb, accidents. This is also where the stop itself gets scrutinized.
• Officer observations. Bloodshot eyes, slurred speech, the odor of alcohol, fumbling for documents, unsteady balance, confused responses.
• Field sobriety test performance. Officer-scored “clues” on HGN, walk-and-turn, and one-leg stand.
• Statements by the defendant. Admissions of drinking, statements about the night, anything inconsistent with normal mental functioning.
• Witness testimony. Bartenders, passengers, other drivers, anyone who saw the defendant before or during the incident.
• Chemical evidence, if available. Even a sub-0.08 reading is corroborative evidence. It confirms alcohol consumption, even if it does not establish per se intoxication, and Texas courts have held that a result is probative on both definitions rather than just the number one.

This is why the State does not need a 0.08 to prosecute. A motivated prosecutor can build an impairment case from observation and testimony alone, and does, in cases where the chemical evidence is weak or absent.

Why the Impairment Prong Is Defendable

The good news for defendants is that the impairment prong is, in many ways, more contestable than the per se prong. Where the per se prong relies on a number that has the appearance of objectivity, the impairment prong relies on subjective observations that have well-known reliability problems. A real defense addresses each category:

• Driving behavior. Lane drift can be caused by texting, fatigue, distraction, mechanical issues, or weather and not just intoxication. Witnesses, dashcam footage, and the timing of any observed driving can all be developed.
• Officer observations. Bloodshot eyes can come from allergies, contact lenses, lack of sleep, or crying. Slurred speech can be a natural speech pattern, anxiety, or a medical condition. The odor of alcohol indicates consumption but not impairment. Fumbling for documents at 2 a.m. with flashing lights in your face is not unusual for sober drivers.
• Field sobriety test performance. Addressed in detail in our field sobriety test post. Conditions, age, weight, footwear, medical conditions and administration errors all confound performance.
• Defendant statements. Statements obtained without proper Miranda warnings or in coercive circumstances may be subject to suppression. Statements elicited through casual conversation are subject to challenge on voluntariness grounds.
• The chemistry. A sub-0.08 result, even if introduced, is consistent with someone who had a drink but not necessarily someone whose faculties were lost. A defense expert can put the number in context.

Because the impairment prong relies on subjective observation, it lives or dies on the credibility of the officer’s narrative. That narrative is almost always testable against video evidence, medical records, and physical reality.

One procedural point worth knowing, because it is a real motion and not a technicality. Even though the specific intoxicating substance is treated as an evidentiary matter rather than an element of the offense, the charging instrument still has to allege which substance the State says caused the intoxication. An information that does not is subject to a motion to quash. In a sub-0.08 case, where the State’s theory may shift between alcohol, a drug, and a combination, that matters more than it does in an ordinary case.

Drug DWI Without Alcohol: The DUID Problem

Texas does not have a per se drug limit. Unlike some states that set numerical thresholds for THC, certain prescription drugs, or controlled substances, Texas requires the State to prove loss of faculties for any drug-related DWI prosecution. That structural choice has practical consequences:

• A positive drug test alone is not enough. A blood test showing a metabolite of cannabis, for example, proves prior use but not impairment at the time of driving. The State has to prove the loss-of-faculties prong independently.
• The chemistry of cannabis is not the chemistry of alcohol, and the difference favors the defense. Alcohol clears at a fairly predictable rate, which is what makes back-calculation possible at all. THC does not behave that way, so there is no reliable way to work backward from a single blood number to what was in your system when you were driving. And the federal government has said plainly, in a 2017 report to Congress, that the level of THC in blood and the degree of impairment do not appear to be closely related, and that a blood THC level is not an accurate or reliable predictor of impairment. That is not a defense lawyer’s argument. That is NHTSA.
• Detection is not impairment, and the matrix matters. THC is fat-soluble, so in a chronic daily user low levels of active THC can still be measurable in blood days, and in controlled inpatient studies occasionally weeks, after the last use and long after any effect has worn off. For an occasional user the picture is the opposite: blood THC typically falls below common cutoffs within hours. The inactive metabolite lasts far longer still. A positive result for the inactive metabolite proves past exposure and nothing about the moment of driving. Tolerance complicates it further, since a regular user may show a level that would affect a novice and show no impairment at all.
• A DRE evaluation is an opinion, not a measurement. Drug Recognition Expert evaluations are observational, and the twelve-step protocol produces an opinion about a drug category rather than an identification of a specific drug or a concentration. Texas treats that opinion as scientific expert testimony, which means it can be challenged for reliability before the jury ever hears it. There is also a point that cuts strongly the other way and is worth knowing: an officer who is not a certified DRE generally cannot offer an opinion that a driver was impaired by drugs at all. Texas courts have reversed convictions where an officer testified about the effects of medications without the expertise to do it.
• Prescription medications. A driver taking prescribed medication as directed can still be charged if the State alleges the medication caused loss of faculties. Be clear-eyed about this: the Penal Code says in one sentence that being entitled to use the substance is not a defense. Having a valid prescription is the foundation of a defense, not the defense itself.

DUID cases are some of the most forensically and legally complex DWI prosecutions in Texas, and the field is still moving, including on roadside cannabis testing. They require a defense lawyer who understands both pharmacology and the loss-of-faculties standard.

Combination Cases: Alcohol Plus Something Else

The combination prong of the statute is increasingly common. It explicitly contemplates intoxication caused by “a combination of two or more of those substances”, meaning alcohol plus drugs, alcohol plus medication, or drugs plus medication. In a combination case:

• The BAC may be low. 0.04, 0.05, 0.06, well below the per se limit on alcohol alone.
• The drug or medication may be lawful. A prescribed medication, an over-the-counter cold medicine, or a controlled substance with a valid prescription. Lawful use does not change the analysis, for the reason given in the last section.
• The State’s theory is that the combination produced loss of faculties. The defense response often involves toxicology expertise, pharmacokinetic analysis of the specific substances at the specific concentrations measured, and a challenge to the State’s assumption that any detectable level produced impairment.

There is a limit on how far the State can take this. A jury charge that lets the jury convict on a combination of substances the charging instrument never alleged, without a theory tying it back to what was alleged, has been held to be error. Generic DWI defense rarely produces good outcomes in cases that turn on combined-substance pharmacology, and neither does generic prosecution.

Under-21 Drivers: A Different Standard Entirely

If you are under twenty-one, the framework changes again. Texas takes a zero-tolerance approach. Under Alcoholic Beverage Code §106.041, a minor who operates a motor vehicle in a public place, or a watercraft, with any detectable amount of alcohol in the system commits the offense of Driving Under the Influence by a Minor. “Detectable” means any measurable amount, so not 0.08, not 0.04, but anything the instrument can register.

A first offense is a Class C misdemeanor with the following consequences:

• A first offense carries more than a fine. Conviction brings mandatory community service, twenty to forty hours for a first offense and forty to sixty if there is a prior, and it has to be related to alcohol education or prevention. An alcohol awareness course is also required, and failing to complete it can itself cost the license.
• A third offense is not a Class C at all. A minor who is seventeen or older and has been previously convicted at least twice faces a fine of $500 to $2,000, up to 180 days in jail, or both, and is not eligible for deferred disposition. Prior juvenile adjudications and prior deferred dispositions count toward that total.
• The license consequence starts at the arrest, not the conviction. For a minor, any detectable amount supports an administrative suspension of 60 days, then 120 days with one prior and 180 days with two or more.

This is why the under-21 DUI is fundamentally different from the adult DWI. Adult DWI requires either 0.08 or loss of faculties. Minor DUI requires only that any alcohol be detectable. And the two are not alternatives to each other: the statute says expressly that DUI by a minor is not a lesser included offense of DWI, so a driver under twenty-one who is at 0.08 or who has lost the normal use of their faculties can be charged with driving while intoxicated like anyone else.

The interaction between minor DUI and adult DWI is covered in detail in our post on the difference between DWI and DUI in Texas. The point for purposes of this post is that the 0.08 threshold is even less protective for under-21 drivers than it is for adults.

Why People Believe 0.08 Is the Magic Number and Why That’s Wrong

Public education about DWI tends to focus on the 0.08 number because it is concrete and quotable. “Don’t drive over 0.08” fits on a poster. “Don’t drive impaired by alcohol, drugs, or any combination thereof under the totality of circumstances” does not.

The result is a widespread belief that staying under 0.08 means you are safe from DWI prosecution. That belief is wrong, and it gets people arrested. Officers know about the impairment prong. Prosecutors charge cases under it. Juries can convict on it. Anyone relying on a sub-0.08 reading as a defense is relying on only half of the statute.

It is also worth saying that the stakes do not stop at a misdemeanor. The same definition of intoxication carries into intoxication assault and intoxication manslaughter. A sub-0.08 case in which someone was seriously hurt is a felony, and the absence of a number changes nothing about that.

The Bottom Line

You can be arrested for DWI in Texas with a BAC below 0.08 or with no test result at all. The 0.08 limit is one way to prove intoxication. The loss-of-normal-use-of-faculties standard is the other, and it does not require a chemical test. Drug DWIs, prescription-medication cases, combination cases and refusal cases are all routinely prosecuted on the impairment prong.

Two things to take from this. On the license side, a sub-0.08 result from a sample you actually gave shuts down the administrative suspension, and that is worth knowing within the fifteen days you have to act on it. On the criminal side, the number is not your defense. The defense is a forensic, observational and procedural challenge to the State’s theory of impairment. It is winnable, but it requires a lawyer who understands what the statute actually says and how the State actually charges these cases.

DWI Defense at Deandra Grant Law

Deandra Grant Law defends DWI and intoxication-offense cases across North and Central Texas including Dallas, Fort Worth, Plano, McKinney, Frisco, Allen, Lewisville, Denton, Rockwall, and Waco. We handle the full spectrum of DWI cases, including per se prosecutions, loss-of-faculties prosecutions, drug DWIs, combination cases and refusal cases, and we apply forensic and pharmacological analysis to every one of them. Our team includes an ACS-CHAL Forensic Lawyer-Scientist with a Master of Science in Pharmaceutical Science and a Graduate Certificate in Forensic Toxicology, which are the credentials required to challenge DWI evidence at the level of the science.

If you have been arrested for DWI in Texas with a BAC under 0.08, with no test at all, or in a drug or combination case, call Deandra Grant Law at (214) 225-7117 or visit texasdwisite.com to schedule a confidential consultation. And remember: the 15-day ALR deadline runs from the date of service of the notice of suspension.

Have a DWI question you want answered in this series? Submit it at texasdwisite.com. You might see it featured in a future Ask Deandra post. Unfamiliar terms are defined in our DWI glossary.