If you’ve been arrested for DWI in Texas and the police took your blood, the prosecutor thinks they’ve got you. They’ll wave those test results like they’re bulletproof evidence.
They’re wrong.
Blood tests fail. They fail often. And when they do, cases get DISMISSED.
What if you don’t challenge these tests? You’re looking at a permanent criminal record, thousands in fines, license suspension, and possibly jail time.
At the Law Offices of Richard C. McConathy, our DWI Lawyers have successfully challenged blood tests in numerous cases, leading to dismissals and reduced charges. With over 20 years defending Texas DWI cases, we know exactly how to identify weaknesses in blood test evidence.
Keep reading to discover exactly when police can legally take your blood without consent, how recent Supreme Court decisions have changed the game, and the specific procedural errors that could get your case dismissed.
If you’ve been arrested for DWI and subjected to a blood test in Dallas County, call us today at (972) 528-0116.
Texas Implied Consent Law and Your Rights
Under Texas Transportation Code § 724.011, anyone arrested for a driving while intoxicated (DWI) offense is deemed to have given consent to breath or blood testing.
However, this doesn’t mean you have no rights when it comes to chemical testing.
Your Right to Refuse Testing
Despite implied consent, Section 724.013 of the Texas Transportation Code generally protects individuals from forced blood draws if they refuse testing. You have the right to refuse a blood test in most situations, though this refusal will trigger:
- Administrative license suspension (180 days for first offense)
- The refusal may be used as evidence in court
- Potential use of other evidence to prove intoxication
When You Cannot Refuse: Mandatory Blood Tests
There are specific situations where law enforcement can legally obtain a blood sample without your consent, even without a warrant:
| Circumstance | Legal Authority | Penalties |
|---|---|---|
| Accident causing death or serious injury | Tex. Transp. Code § 724.012(b)(1) | Enhanced charges possible |
| Child under 15 in vehicle | Tex. Transp. Code § 724.012(b)(2) | State jail felony |
| Prior DWI with child passenger | Tex. Transp. Code § 724.012(b)(3) | Enhanced penalties |
| Two or more prior DWI convictions | Tex. Transp. Code § 724.012(b)(3) | Felony charges possible |
Blood Test Procedures and Legal Requirements
For a blood test to be admissible in court, it must adhere to strict procedures outlined in Texas Transportation Code § 724.017:
- Qualified personnel requirement – Only physicians, registered nurses, licensed vocational nurses, qualified technicians, or chemists may draw blood
- Sanitary conditions – The blood must be drawn in a sanitary environment
- Proper storage and handling – The sample must be properly preserved and maintained
- Chain of custody – Documentation must show who handled the sample at all times
❗ Our firm has successfully challenged blood tests by proving violations of these requirements, leading to case dismissals for our clients.
Recent Changes in DWI Blood Testing Law
Recent Texas court decisions have significantly impacted how blood test evidence is handled:
- Missouri v. McNeely (2013) – The Supreme Court ruled that the natural dissipation of alcohol in the bloodstream does not automatically create an exigent circumstance justifying a warrantless blood draw
- State v. Villarreal (2014) – The Texas Court of Criminal Appeals ruled that the mandatory blood draw statute cannot override the Fourth Amendment’s warrant requirement
- Birchfield v. North Dakota (2016) – The Supreme Court held that warrantless blood tests incident to arrest for drunk driving violate the Fourth Amendment
These rulings have created powerful opportunities to challenge blood test evidence that we leverage in your defense.
Drug DWI Blood Tests: Special Considerations
If you’re suspected of driving under the influence of drugs, the testing and defense considerations are different:
- Blood tests can detect prescription medications, illegal drugs, and marijuana
- Unlike alcohol, drug metabolites can remain in your system long after any impairment has subsided
- The presence of a drug does not automatically prove impairment at the time of driving
We frequently challenge these Drug DWI cases by demonstrating that:
- The presence of a drug does not prove recent use
- Tolerance levels vary significantly between individuals
- The prosecution cannot establish a direct link between detected substances and actual impairment
Effective Strategies to Challenge Blood Test Evidence
At the Law Offices of Richard C. McConathy, we employ various strategies to challenge blood test evidence:
🛡️ Procedural Challenges
- Lack of probable cause for the initial traffic stop
- Improper administration of the blood draw
- Warrant deficiencies if a warrant was obtained
🛡️ Scientific Challenges
- Fermentation of the blood sample causing artificially high results
- Contamination issues in collection or storage
- Improper calibration of testing equipment
🛡️ Constitutional Challenges
- Fourth Amendment violations related to unreasonable searches
- Fifth Amendment issues regarding self-incrimination
- Due process concerns in the handling of evidence
Real Case Results: Blood Test Cases We’ve Won
Our track record in blood test DWI cases speaks for itself. Here are actual case results from our practice:
- DWI Blood Test Case + Prescription Meds, Dismissed (CR200606211)
- DWI Blood Test Case, Result Of .14, Dismissed (MB0451204 CCC7)
- DWI Blood Test + Prescription Meds, Dismissed (CR200606211)
- Intoxication Assault, Breath Test Case, Result of .17, Dismissed (F09-52586)
- Intoxication Assault, Breath Test Case, Result of .17, Dismissed (F09-71478)
- Intoxication Assault, Breath Test Case, Result of .17, Dismissed (F10-00757)
Administrative License Suspension After a Blood Test
Even if your criminal case is dismissed, you may still face administrative penalties:
| Situation | Suspension Period | Eligibility for Occupational License |
|---|---|---|
| First offense refusal | 180 days | After 90 days |
| Multiple offense refusal | 2 years | After 1 year with restrictions |
| Failed test (≥0.08 BAC) | 90 days | Immediately with restrictions |
| Failed test with priors | 1 year | After 90 days with restrictions |
We handle both the criminal and administrative license suspension aspects of your case, fighting to protect your driving privileges while defending against criminal charges.
Why Choose the Law Offices of Richard C. McConathy
When facing DWI blood test charges in Dallas County, experience matters:
- Over 20 years defending DWI cases in Dallas, Collin, Tarrant, and surrounding counties
- Specialized knowledge of blood testing procedures and scientific challenges
- Proven track record of dismissed cases and reduced charges
- Personalized defense strategy tailored to your specific situation
- Aggressive advocacy at both criminal and administrative proceedings
What Our Clients Say
“The other driver was injured and it was determined that my blood alcohol level was 0.15. I was being charged with intoxication assault and I had no idea what that even meant, but it carried a penalty up to 10 years in prison. Richard’s team was tenacious. They told me they were gonna fight this to the end in court. They were able to get the blood test dismissed and my case was dismissed. I can’t thank Richard and his team enough.” — Former Client
Contact Us for a Strong DWI Blood Test Defense
If you’re facing DWI charges involving a blood test in Texas, don’t wait to get the defense you need.
The sooner we can begin investigating your case, the better your chances of a favorable outcome.
Call the Law Offices of Richard C. McConathy today at (972) 528-0116 or contact us online to discuss your case and explore your defense options.
The Law Offices of Richard C. McConathy understand every case is unique. Whether you are facing a DWI charge in Dallas, an intoxication assault case in Plano, or any other alleged crime, our lawyers will give your case the highest levels of attention.
Frequently Asked Questions About DWI Blood Tests
Can I refuse a blood test in Texas?
Yes, in most situations you can refuse a blood test. However, this refusal will result in an automatic license suspension under Texas’ implied consent law. There are specific exceptions where a mandatory blood draw may be legal, such as when there’s a serious injury accident or when a child under 15 was in the vehicle.
How accurate are blood tests for DWI cases?
While blood tests are generally considered more accurate than breath tests, they are far from infallible. Improper collection, storage, or testing procedures can all lead to inaccurate results. Even properly administered tests have a margin of error that can be significant in borderline cases.
Can prescription medications lead to a DWI blood test charge?
Yes. Texas law prohibits driving while intoxicated by any substance, including legally prescribed medications. If a blood test reveals prescription drugs in your system and the prosecution can prove these medications impaired your driving ability, you can be charged with DWI.
How long does alcohol stay in your blood for testing purposes?
The body eliminates alcohol at an average rate of about 0.015% BAC per hour. This means it takes approximately 5-6 hours to eliminate 0.08% BAC from your system. However, individual factors like metabolism, gender, weight, and food consumption can affect this rate.
Will I lose my license if I fail a blood test?
Yes, if your blood test shows a BAC of 0.08% or higher, the Texas Department of Public Safety will automatically suspend your license. This administrative suspension is separate from any criminal penalties and will occur even if you’re not convicted of DWI. You have only 15 days from your arrest to request an Administrative License Revocation (ALR) hearing to contest this suspension.