Houston DWI Breath Test Defense Attorney

DWI Breath Test Defense Attorney in Houston, TX

Cory Roth Law Office defends Houston, TX clients arrested for DWI after a breath test. We challenge Intoxilyzer 9000 results, attack flawed police procedure, fight ALR license suspensions, and expose calibration and operator errors—so failed breath tests do not become automatic convictions.

What Is a DWI Breath Test in Texas?

A DWI breath test is a chemical analysis of your breath used to estimate your blood alcohol concentration (BAC). In Texas, the legal limit for most drivers is 0.08% BAC. A reading at or above 0.08% is considered “per se” intoxicated under Texas Penal Code Section 49.01.

There are two categories of breath testing devices used in Texas:

• Portable Breath Tests (PBTs) — handheld roadside screening devices. PBT results are generally not admissible at trial in Texas but can be used to establish probable cause for arrest.
• Evidentiary Breath Tests — administered after arrest using the Intoxilyzer 9000 at a police station or DWI processing facility. These results can be introduced as evidence at trial.

Understanding the difference matters. A roadside handheld test does not carry the same weight as the station test, but officers often use it to justify the arrest that leads to the evidentiary test.

The Intoxilyzer 9000 — Texas’s Breath Test Machine

The Intoxilyzer 9000 replaced the older Intoxilyzer 5000 as the standard evidentiary breath testing instrument across Texas. The machine is manufactured by CMI, Inc. and approved by the Texas Department of Public Safety (DPS) Breath Alcohol Testing Program.

The Intoxilyzer 9000 uses infrared (IR) spectroscopy to measure the amount of alcohol in a deep-lung breath sample. The machine assumes a fixed ratio between breath alcohol and blood alcohol—a 2,100:1 “partition ratio”—based on a theoretical principle called Henry’s Law.

Here is what the State doesn’t tell you: that partition ratio is an average. Real human partition ratios vary widely—from roughly 1,100:1 to 3,200:1 depending on body temperature, breathing pattern, and physiology. When the State applies one number to every defendant, the result is a calculated estimate, not a direct measurement.

How Texas Breath Tests Actually Work

A breath test does not measure alcohol in your blood. It measures alcohol vapor in the air you exhale and applies a mathematical assumption to estimate your blood alcohol. That gap—between what is measured and what is reported—is where breath test defense begins.

Henry’s Law and the Partition Ratio

Henry’s Law states that at a constant temperature and pressure, the concentration of a substance dissolved in liquid is proportional to its concentration in the gas above the liquid. The Intoxilyzer 9000 relies on this principle to convert breath alcohol into a BAC estimate.

But Henry’s Law assumes the breath sample is at exactly 34°C (93.2°F) and that your partition ratio matches the assumed 2,100:1. In reality, neither assumption holds true for every person, every time.

Body Temperature and Breath Temperature

Research shows that for every 1°C increase in body temperature, breath alcohol readings can rise by approximately 6.5% to 8.6%. A person with a fever, a hot car, or natural physiological temperature variation can register a falsely elevated BAC.

Breathing Pattern Effects

How you breathe into the machine affects the result. Holding your breath before blowing or exhaling forcefully from deep in the lungs can raise readings. Hyperventilating before the test can lower them. Officers are supposed to follow a strict observation and instruction protocol—when they don’t, the results are unreliable.

Texas Implied Consent Law — Transportation Code Chapter 724

Under Texas Transportation Code Chapter 724, anyone who drives on Texas public roads is deemed to have given “implied consent” to a breath or blood test if arrested on suspicion of DWI. But “implied consent” doesn’t mean unlimited consent—the law requires the officer to follow specific procedures.

Section 724.015 — Required Warnings Before Testing

Before requesting a breath specimen, the officer must inform you—orally and in writing—of the consequences of refusing or failing. Failure to give the proper statutory warnings can become the basis to suppress the test result.

Section 724.012 — Mandatory Specimen Situations

In certain circumstances, the officer must require a specimen even if you refuse. These include accidents involving serious bodily injury or death, repeat-DWI suspects, and arrests involving a child passenger. In those cases, officers typically apply for a search warrant for a forced blood draw.

Section 724.061 — Refusal Can Be Used at Trial

A refusal is admissible against you. Prosecutors may argue refusal as “consciousness of guilt.” That doesn’t mean refusal is always the wrong call—but it does mean the decision has consequences either way.

Should You Refuse a Breath Test in Houston?

There is no universally correct answer. The decision involves weighing immediate license consequences against the strength of the case the State would build with a test result.

If You Refuse

• Automatic 180-day license suspension on a first refusal under Chapter 724.
• Two-year suspension for a second refusal within 10 years, or with a prior alcohol-related contact.
• The refusal itself becomes admissible evidence at trial.
• The State may obtain a search warrant and draw your blood by force.
• You deny the prosecution a specific BAC number—a tactical advantage at trial.

If You Submit and Fail

• Automatic 90-day license suspension if your BAC is 0.08% or higher.
• One-year suspension with prior alcohol-related contacts.
• The State has a specific number to argue against you.
• But the result becomes attackable—calibration, observation, operator, science.

The honest truth: refusing avoids handing the State easy evidence, but it triggers longer suspensions. Submitting gives the State a number, but the number becomes vulnerable to attack. A Houston DWI attorney who has fought both fact patterns can advise on what to do before you ever face that choice—and how to recover after.

The ALR Hearing — You Have 15 Days

An Administrative License Revocation (ALR) hearing is a separate civil proceeding from your criminal DWI case. It determines whether DPS can suspend your driver’s license based on the breath test result or refusal. The deadline to request the hearing is strict.

The 15-Day Rule

You must request an ALR hearing within 15 days of the date of the notice of suspension (typically issued at arrest as a temporary driving permit). Miss this deadline and your suspension becomes automatic on the 40th day after arrest. There is no extension.

Why the ALR Hearing Matters

• You can fight to keep your license active during your criminal case.
• Your attorney can subpoena and cross-examine the arresting officer under oath.
• Officer testimony at ALR becomes a discovery tool for your criminal trial.
• Inconsistencies between ALR and trial testimony can be used at trial.
• A win at ALR avoids the license suspension entirely.

Many drivers don’t realize the ALR is a separate process. By the time they hire counsel for the criminal case, the 15 days have passed and the license is gone. Hiring a DWI attorney within days of arrest is essential to preserve every option.

How We Challenge Breath Test Results in Houston

Breath tests are not infallible. They can be attacked on legal, procedural, and scientific grounds. Our defense team systematically examines each of the following:

1. The Traffic Stop Itself

Was there reasonable suspicion to pull you over? Without a lawful stop, every test that follows can be suppressed under the Fourth Amendment and Texas Code of Criminal Procedure Article 38.23 (the Texas exclusionary rule).

2. Probable Cause for Arrest

An officer needs probable cause—not just a hunch—to arrest you. We review dashcam, bodycam, field sobriety performance, and the officer’s report for gaps in the probable cause chain.

3. The 15-Minute Observation Period

Texas DPS rules require the breath test operator to keep you under continuous observation for at least 15 minutes immediately before the test. The purpose is to ensure you did not burp, regurgitate, vomit, eat, drink, or place anything in your mouth. If the operator left, looked away, or filled out paperwork instead of watching you, the observation period is broken.

4. Operator Certification

Only DPS-certified breath test operators can administer evidentiary tests. We pull the operator’s certification record and verify it was current on the date of your test. An expired or invalid certification means the test should not be admitted.

5. Machine Calibration and Maintenance

Every Intoxilyzer 9000 must be inspected, calibrated, and maintained by a Technical Supervisor on a regular schedule. We obtain the inspection logs, reference sample records, and any service tickets. Lapses in calibration, repairs, or maintenance create grounds to challenge the result.

6. The Two-Sample Rule and .02 Tolerance

DPS regulations require two samples within 0.02 of each other. That tolerance is wide enough to span the legal limit. A 0.07 and a 0.09 are both reported as legally meaningful. We argue what that tolerance actually means: real uncertainty about the true BAC.

7. Radio Frequency Interference (RFI)

The Intoxilyzer 9000 is sensitive to RFI. Police radios, cell phones, dispatch equipment, and electronic devices in the testing room can affect readings. We investigate the testing environment for sources of interference.

8. Mouth Alcohol Contamination

Residual alcohol from dental work, mouthwash, breath sprays, recent drinks, GERD reflux, or even certain medications can sit in the mouth and skew breath test results upward. The 15-minute observation period is designed to address this—but only if it was actually performed.

9. Medical and Physiological Conditions

Multiple medical conditions can cause falsely elevated breath readings. We work with medical experts to document conditions that affected your test (see the dedicated section below).

10. Statutory Warnings (DIC-24)

Before requesting a breath sample, the officer must read the DIC-24 statutory warnings under Section 724.015. If the officer skipped warnings, gave them improperly, or used coercion, suppression is on the table.

11. Chain of Custody and Documentation

Every breath test generates documentation—a test slip, a maintenance log, video, the officer’s report. We compare all of it. Inconsistencies create reasonable doubt.

Medical Conditions That Can Skew Breath Tests

Breath testing is not one-size-fits-all. Common medical conditions can produce false-high readings on the Intoxilyzer 9000:

• GERD / Acid Reflux — stomach contents can bring alcohol back into the mouth, contaminating the breath sample.
• Hiatal Hernia — similar to GERD, can cause alcohol from the stomach to enter the breath stream.
• Diabetes / Ketosis — diabetics in ketosis produce acetone, which infrared breath machines can mistake for ethanol.
• Low-Carb / Keto Diet — similar ketone production from extreme low-carb diets.
• Asthma Inhalers — many contain ethanol that lingers in the mouth and airway.
• Fever or Elevated Body Temperature — directly raises reported BAC under Henry’s Law calculations.
• Dental Work — bridges, crowns, and dentures can trap mouth alcohol.
• Recent Cigarette Use — can affect machine response in some studies.

If you have any of these conditions, document them. Medical records, prescriptions, and physician statements become powerful defense evidence.

Refusal, Search Warrants, and Forced Blood Draws

Refusing the breath test does not always end the chemical testing. In Texas, officers can apply for a search warrant authorizing a forced blood draw. In Harris County and surrounding counties, this happens regularly—especially during “no-refusal” enforcement periods.

No-Refusal Weekends in Harris County

During holidays and high-enforcement weekends, Harris County prosecutors and judges are on standby. If you refuse a breath test, an officer can fax a warrant application and have a blood draw warrant signed within minutes. Knowing this changes the calculus of refusal.

Section 724.012(b) — Mandatory Blood Draws

Even without a warrant, Texas law mandates a specimen if there was an accident with serious bodily injury or death, a child passenger, or repeat-DWI history. Refusal does not stop a mandatory draw.

Challenging the Blood Draw Itself

If your refusal led to a forced blood draw, the chain of custody, warrant validity, draw procedure, and lab testing all become attackable. The same defense rigor we apply to breath tests applies to blood tests.

DWI Penalties at Stake in Houston

A breath-test DWI conviction carries serious consequences under Texas Penal Code Chapter 49. Even a first offense can result in:

• Up to 180 days in jail (Class B misdemeanor first DWI).
• Up to one year in jail (Class A misdemeanor for BAC of 0.15 or higher).
• Up to $4,000 in fines, plus state surcharges and court costs.
• License suspension of 90 days to one year.
• DWI education program requirements.
• Ignition interlock device installation.
• Significant insurance rate increases.
• A permanent criminal record visible to employers and landlords.

Charges escalate quickly. A first-offense DWI can become a felony DWI if you have prior convictions, a child passenger, a commercial driver’s license, or a third DWI offense. Cases involving serious injury can be charged as intoxication assault.

Texas DPS Breath Alcohol Testing Regulations

The Texas Administrative Code Title 37, Part 1, Chapter 19 governs how breath alcohol testing must be conducted in Texas. Any meaningful departure from these rules can be grounds to exclude the test result. Key requirements include:

• The breath testing instrument and reference sample device must be operated only by certified operators or technical supervisors.
• A 15-minute pre-test observation period must be maintained without interruption.
• Two samples must be obtained within a 0.02 g/210L tolerance of each other.
• The instrument must be inspected and certified by a Technical Supervisor at required intervals.
• Reference sample (calibration) records must be maintained and produced on request.

When the State fails to follow these rules, Texas case law and Code of Criminal Procedure Article 38.23 provide a jury instruction telling jurors they must disregard the test result. That instruction alone has won countless DWI cases.

Why Choose Cory Roth Law Office for Your Breath Test Defense

Attorney Cory Roth has a record of dismissals, not-guilty verdicts, and grand jury no-bills in Harris County and surrounding counties. DWI breath test cases reward thorough preparation—pulling the records, mastering the science, and trying the case if necessary. That’s how we work.

What sets our defense apart:

• Aggressive ALR hearing strategy within the 15-day window.
• Subpoena of Intoxilyzer 9000 maintenance and calibration records.
• Independent review of bodycam, dashcam, and stationhouse video.
• Coordination with toxicology and breath testing experts.
• Trial-ready preparation from day one, not just plea negotiation.
• Direct attorney access—Cory Roth handles your case personally.
• Honest assessment of strengths and weaknesses before you sign.

See our DWI case results or learn more about Cory Roth.

Fight Your Breath Test. Protect Your License.

A failed or refused breath test is not the end of your case. With the right defense, those numbers and that refusal can be turned into reasonable doubt—or knocked out of the case entirely. Cory Roth Law Office knows the Intoxilyzer 9000 inside and out, the DPS regulations that govern its use, and the procedural mistakes that get tests excluded.

Call (832) 346-7551 today for a free, confidential consultation. We accept calls day and night, including weekends. Or contact us online. The clock on your ALR hearing started the moment you were arrested—let’s not waste another day.