Texas DWI Law Explained: What Is the Texas DUI Blood Alcohol Level?

The Texas DUI blood alcohol level is 0.08 for most adult drivers, 0.04 for commercial drivers while operating a commercial vehicle, and “any detectable alcohol” for drivers under 21 under Texas’s zero‑tolerance rules. These thresholds are statewide and apply in Houston and across Harris County. Even below 0.08, you can still face a DWI if officers and evidence suggest your normal mental or physical faculties were impaired by alcohol, drugs, or a combination.

Quick answer for worried Houston drivers

If you’re a working driver in Houston, here are the numbers that matter most:

• 0.08 BAC Texas DWI: Adult non‑commercial drivers are “per se” intoxicated at 0.08% blood alcohol concentration.
• 0.04 BAC for CDL drivers Texas: Commercial driver’s license (CDL) holders are held to 0.04% while operating a commercial motor vehicle.
• Zero tolerance BAC minors Texas: Under 21 is “any detectable alcohol.” A minor can face a DUI (by a minor) even at 0.01–0.02%.
• 15‑day ALR clock: After a DWI arrest or a test refusal/failure, you typically have 15 days to request an ALR hearing to contest the proposed license suspension.

You need clear information fast because your ability to drive to the jobsite or take your kids to school may depend on what you do in the next two weeks.

DWI BAC Chart Texas: simple thresholds at a glance

Use this quick chart as a baseline. It summarizes the legal limit for DUI/DWI in Texas by driver type. For a deeper primer, see our straightforward explanation of Texas DWI and BAC rules.

Driver Type	Texas DUI Blood Alcohol Level / Trigger	Notes
Adult, non‑commercial (21+)	0.08% BAC (per se)	Below 0.08 can still lead to DWI based on loss of normal mental/physical faculties.
CDL holder in a commercial vehicle	0.04% BAC	CDL disqualification rules are strict; an occupational license does not restore CMV driving.
Under 21 (minor)	Any detectable alcohol	Texas has zero tolerance. Minors can also be charged with adult DWI at 0.08% or impairment.

Important: “BAC” means blood alcohol concentration measured by breath or blood testing. Officers can also rely on observed impairment, field sobriety tests, and other evidence. If your BAC is under 0.08 but you appear impaired, a DWI charge is still possible.

What “DWI” and “DUI” mean in Texas (and why the terms cause confusion)

People search “what is DUI blood alcohol levels” and get mixed answers because Texas uses two different terms. For adults 21 or older, the charge is generally DWI (Driving While Intoxicated). For drivers under 21, the charge related to alcohol is often DUI by a Minor. Both can involve a breath or blood test, but the standards are not the same:

• DWI applies statewide to adults at 0.08% per se or to anyone (adult or minor) whose normal faculties are impaired by alcohol or drugs.
• DUI by a Minor applies to under‑21 drivers where any detectable alcohol is enough to trigger an offense, even well below 0.08%.

For you as a Houston construction manager trying to protect your job and license, focus on the 0.08 (adult), 0.04 (CDL in a CMV), and zero‑tolerance (under 21) lines—those are the bright‑line triggers officers and courts use day in and day out.

How Texas measures BAC and why “under the limit” can still mean charges

Texas officers commonly use breath testing devices at or after arrest and may request a blood draw, especially on “No‑Refusal” operations in Harris County or nearby counties. The legal definition of intoxication covers two paths:

• Per se intoxication: 0.08% BAC or higher (0.04% for CDL while driving a commercial vehicle).
• Impairment evidence: loss of normal mental or physical faculties because of alcohol, drugs, or a combination—even if chemical test results are below 0.08%.

That means a driver at 0.07% who is weaving, slurring, or failing field sobriety tests can still face DWI. On the other hand, chemical test results can be challenged if the machine was not properly maintained, if the sample was contaminated, or if the timing of the test suggests the BAC was rising.

If you’re a CDL holder in Houston

CDL cases carry special risks. The 0.04% standard applies when you are operating a commercial motor vehicle. A DWI or certain alcohol‑related violations can trigger CDL disqualification, often for 1 year on a first disqualifying event (longer if hazardous materials are involved or if there are prior disqualifications). You cannot use an occupational license to drive a commercial vehicle while disqualified.

If you manage crews or haul materials around Harris County, a CDL hit can ripple through your employment. Early, informed action—especially on the ALR license side—can protect your ability to keep working in a non‑CMV while your case is pending.

Real Houston story (anonymized): the 0.09 at a stoplight

“J,” a mid‑30s Houston construction manager, left a client dinner near the Heights and rolled a stop a little late. The officer noted an odor of alcohol. J took a breath test that read 0.09% at the station. He panicked over losing his license and missing morning safety meetings. Here’s what mattered most for J in the first week:

• He learned that 0.08% is the per se line, but case outcomes still turn on the stop, testing, and evidence quality.
• He marked his calendar to request the ALR hearing within 15 days of the notice, so his license wouldn’t automatically suspend on about the 40th day.
• He explored whether an occupational license could keep him driving to work if a suspension started.
• He gathered job records and shift schedules to show genuine need to drive and to prepare for potential license relief.

You may be in a similar spot after a weekend stop on I‑610 or near a jobsite in Spring Branch. The faster you understand the BAC thresholds and the ALR deadlines, the more options you’ll have to protect your ability to work.

ALR 15‑day deadline and practical next steps

Texas uses the Administrative License Revocation (ALR) process to handle driver’s license consequences after a DWI arrest, a test failure (0.08+ adults or 0.04+ in a CMV for CDL), or a test refusal. You generally have 15 days from the date you receive the notice of suspension to request a hearing. If you do nothing, a suspension often begins on or about the 40th day after that notice.

For a step‑by‑step outline, see our guide to how to request an ALR hearing and preserve your license. For a neutral overview of the statewide process, the Texas Department of Public Safety offers a helpful page: Texas DPS overview of the ALR license process.

What to do in the first 72 hours

• Mark the 15‑day window: Count 15 calendar days from the date on your notice to preserve your hearing rights.
• Collect documents: Temporary driving permit, any receipts, tow paperwork, and personal notes about what happened.
• Work needs: Sketch your weekly driving needs (commutes, jobsite travel, child care). This helps if you later pursue an occupational license.
• Consider representation: Because ALR hearings are technical and separate from the criminal case, speaking with a qualified Texas DWI lawyer can help you protect your driving privileges.

Penalties and license consequences at common BAC levels

Exact outcomes depend on your record, the evidence, and how the case is handled, but these general ranges apply across Texas, including Harris County:

• DWI 1st (Class B misdemeanor): Up to 180 days in jail and up to a $2,000 fine; driver’s license consequences handled through ALR (often 90 days on a test failure; 180 days on a refusal).
• DWI 1st with 0.15% or more (Class A): Up to 1 year in jail and up to a $4,000 fine; ignition interlock is commonly a bond or probation condition.
• DWI with child passenger (under 15): State jail felony; penalties and collateral consequences increase significantly.
• CDL impacts: A disqualification can be 1 year on a first disqualifying event and longer for subsequent events; an occupational license does not authorize CMV driving.

Remember: The ALR suspension is administrative and separate from the criminal DWI case. You can win one and lose the other, and the timelines are different.

How age and license type change your situation

Adults 21+

At or above 0.08% is per se intoxication. But impairment evidence below 0.08 still matters. If your Houston stop involved a crash, slurred speech, or poor field sobriety tests, officers may rely on the impairment path even if the printout shows 0.07%.

CDL holders

At or above 0.04% in a commercial motor vehicle triggers the lower per se standard. Separate federal and state rules apply to CDL disqualifications. If commercial driving is your livelihood, act within the 15‑day ALR window and plan for how you’ll handle non‑CMV driving in the meantime.

Minors under 21

Zero tolerance means any detectable alcohol can support a DUI by a Minor charge under Texas law. Minors can also face adult DWI if 0.08% or if impaired. For families in Harris County, this often means balancing school, work, and court dates—and understanding the difference between the two charges.

Common misconceptions we see in Houston

• Myth: “Under 0.08 means I’m safe.” Reality: You can be charged with DWI based on impairment evidence even below 0.08—and CDL and under‑21 rules use lower or zero thresholds.
• Myth: “The license issue will wait.” Reality: The ALR clock starts right away, and the hearing request is typically due within 15 days.
• Myth: “I refused, so there’s no case.” Reality: Refusal can lead to a longer administrative suspension and officers can seek a warrant for a blood draw.
• Myth: “I can use an occupational license to keep my CDL driving.” Reality: An occupational license does not authorize you to drive a commercial motor vehicle.

Testing, science, and defensible issues a lawyer may evaluate

• Stop and detention: Why were you stopped? Was there reasonable suspicion?
• Field sobriety testing: Were instructions clear? Were conditions (lighting, footwear, injuries) considered?
• Breath testing: Device maintenance, calibration logs, operator certification, and medical conditions (GERD, diabetes) that can skew readings.
• Blood testing: Chain of custody, anticoagulant and preservative ratios in the vial, fermentation issues, and lab quality controls.
• Timing and rising BAC: A test taken well after driving may read higher than at the time of driving.

Technical note for the Analytical Professional: Texas’s implied‑consent and testing rules are outlined in the statute covering chemical tests. You can review the Texas statute on implied consent and chemical tests for the legal backbone behind refusals, warrants, and license actions. If you like interactive explainer formats, explore this interactive Q&A on Texas BAC limits and variations for additional context.

Houston‑specific notes on process and logistics

Most first‑appearance settings for misdemeanor DWI in Harris County occur at the criminal courthouse complex downtown. ALR hearings, however, are separate administrative proceedings and may be scheduled by the State Office of Administrative Hearings. If you live or work across county lines—Fort Bend, Montgomery, Galveston—the BAC thresholds remain the same, but dates and locations for court and ALR proceedings can differ.

For you, the practical goal is simple: keep lawful driving privileges for work and family, avoid license surprises, and make informed decisions in the criminal case. Mark deadlines, keep documents organized, and consider professional guidance early.

Short guidance for each type of reader

Analytical Professional: You want sources. In addition to the Harris County‑focused guidance above, the DPS page gives a statewide procedural map of ALR deadlines and outcomes. See the Texas DPS overview of the ALR license process and the Texas statute on implied consent and chemical tests for primary references.

Career-Focused Executive: Discretion and speed matter. You may need a plan that limits public court appearances and keeps your schedule clear for board meetings. A tailored approach can include early ALR hearing requests, proactive interlock planning if required, and confidential meeting options.

Licensed-Profession Worker: Nurses, engineers, and other licensed professionals often have reporting duties. Learn whether your board requires self‑reporting or whether an outcome short of conviction can avoid mandatory reports. Protect your license by understanding the BAC thresholds and how administrative and criminal cases interact.

High-Net-Worth Client: You may prioritize privacy, travel flexibility, and minimizing any business disruption. A plan that tracks court settings around your calendar, addresses ALR risks, and considers record‑sealing options (where legally available) can reduce damage to reputation.

Young Nightlife Professional: Zero tolerance means any detectable alcohol under 21. A “quick ride home” decision can cost thousands in fines, classes, and insurance hikes. A rideshare is cheaper than even the first court date’s time off work.

Practical checklist: what to do this week

• Confirm your BAC threshold: 0.08 (adult), 0.04 (CDL in a CMV), zero tolerance if under 21.
• Track your ALR deadline: Count 15 days from the notice date; set calendar alerts for days 10, 13, and 15.
• Gather evidence: Receipts, texts, and location data that show timing of drinks and driving.
• Employment needs: Write down routes, start times, and jobsite locations—useful for an occupational license request if needed.
• Consider counsel: A qualified Texas DWI lawyer can help coordinate the criminal case and the administrative license process so you protect your right to drive.

Frequently asked questions about the Texas DUI blood alcohol level (Houston edition)

What is the legal limit for DUI/DWI in Texas?

For adults 21 and over, the per se limit is 0.08% BAC. For CDL drivers operating a commercial vehicle, the limit is 0.04%, and for drivers under 21, Texas enforces zero tolerance for any detectable alcohol. Even below 0.08, officers can charge DWI if they believe alcohol or drugs impaired your normal faculties.

Can I be arrested in Houston if my BAC is under 0.08?

Yes. Texas law allows a DWI based on impairment evidence even below 0.08. Poor driving, slurred speech, unsteady balance, or failing field sobriety tests can support a charge despite a sub‑0.08 result.

How long do I have to request an ALR hearing after a DWI arrest?

Generally, you have 15 days from receiving the notice of suspension to request an ALR hearing. If you miss the deadline, a suspension often starts on or about the 40th day after notice, unless a hearing is requested and a stay is granted.

What happens to my license in Harris County if I failed or refused the test?

A test failure commonly leads to a proposed 90‑day administrative suspension, and a refusal commonly leads to a proposed 180‑day suspension. These are separate from any criminal penalties, and you can challenge the administrative suspension through the ALR hearing process.

Do CDL drivers have different consequences at 0.04% in Texas?

Yes. CDL holders face a 0.04% per se standard while driving a commercial motor vehicle and strict disqualification rules. An occupational license cannot restore your ability to drive a commercial vehicle while the CDL is disqualified.

Why acting early matters for your job and license

Your Houston workday starts early. Court and ALR deadlines do not wait. The “per se” numbers—0.08, 0.04, and zero tolerance—tell you whether the law presumes intoxication, but your decisions in the first two weeks often determine whether you keep driving legally while the case moves forward. Early information helps you plan for work, family, and transportation, and it gives you more room to address both the evidence and the license side.

This article is educational and general in nature. Everyone’s facts are different. If you have questions about how these BAC thresholds and ALR timelines apply to you, consider speaking with a qualified Texas DWI lawyer who can evaluate the specifics of your situation.

Butler Law Firm - The Houston DWI Lawyer
11500 Northwest Fwy #400, Houston, TX 77092
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