DWI Blood Test

Police officers use chemical tests to determine a person’s impairment level. However, when controlled substances are involved it can be a little more difficult. Law enforcement may ask you to submit to a blood draw to determine if any narcotics are in your system while driving.

Blood tests for DWI can be tricky. This is because blood analysis is the most accurate out of the three chemical tests. It also requires a scientific background to read the results in comparison to breath analysis. All of this information doesn’t mean blood tests are without fault. There are many external and environmental factors which could skew your results.

If you or someone you know has been charged with DWI because of a blood draw, it’s imperative you seek legal counsel.

DWI Attorney for Blood Tests in Harris County, Texas

Chemical testing is a tool utilized by law enforcement to determine your impairment level. Unfortunately, not all chemical test readings should be trusted. If you or someone you know has been charged with DWI, it’s imperative you seek legal representation.

Call the attorneys at Tyler Flood & Associates, Inc. for a quality defense. We have represented residents in the Harris County area for years. Contact us at (713) 224-5529 to set up a free consultation today. Tyler Flood & Associates, Inc. defends people accused of DWI throughout the greater Harris County area including Houston, Tomball, Bellaire and West University Place.

Overview of DWI Blood Testing in Texas

Why Do Police Officers Use Blood Analysis for DWI?

Law enforcement uses chemical testing to determine a person’s blood-alcohol concentration (BAC). If their BAC is at .08 or higher, then the officer is legally required to arrest them of DWI. When it comes to controlled substances, however, it’s much more difficult to determine BAC.

This is why officers will sometimes defer to blood analysis if they can’t get a BAC reading of .08 or higher. Blood analysis is considered the most accurate out of the three tests, breath, urine and blood. It can give a much more reliable reading than breath or urine analysis if narcotics are involved. Police officers might also have an unconscious person undergo a blood test if they were involved in deadly accident.

Back to top

Problems with Blood Testing for DWI

All chemical tests are susceptible to human error, even blood analysis. Certain external and environmental factors could skew your results and jeopardize your freedom. Factors such as outdated equipment or contaminated samples could lead to false results.

Listed below are some issues associated with DWI blood testing.

  • Contaminated samples;
  • Unsanitary testing conditions;
  • Outdated testing kit;
  • Failure to sterilize medical equipment;
  • Sample decomposition;
  • Mislabeled sample;
  • Poorly stored sample;
  • Alcohol contamination of the sample during sterilization;
  • The sample was taken by an unauthorized person;
  • Inadequate training;
  • Break in chain of custody creating confusion;
  • Inability to convert serum or plasma blood;
  • Second blood test gives vastly different results; and
  • Failing to take two samples

Back to top

Should I Refuse Blood Testing for DWI in Texas?

A question many criminal defense lawyers are asked is: “should I submit to blood analysis for DWI?” The answer should be no. Many factors could influence your test and lead to a misleading BAC and a DWI.

It’s important you understand refusing chemical testing may come with some consequences. Your license will be automatically suspended for up to 180 days for refusing a chemical test. Repeat refusals will enhance the suspension term for up to two years.

While it’s a hassle to deal with a suspended license, it’s much easier than a DWI conviction. You can contest your license suspension with an administrative license revocation hearing. The hearing will be a chance for you to hire legal representation and fight your license suspension.

You must know that you could be arrested for refusing chemical testing. Officers reserve the right to arrest you if they have probable cause you were DWI. The police officer could take your refusal as a sign you are intoxicated. You might be booked for a short period of time, but the prosecution may not have concrete evidence against you.

Back to top

Additional Resources

Administrative License Revocation Program – Visit the official website of the Texas Department of Public Safety (DPS) to learn more about their ALR program. Access the site to read about their suspension terms, ALR hearing and how to get an occupational license.

Texas DWI Laws – Visit the official website of the Texas Penal Code to learn more about their DWI laws. Access the site to read their penalties, possible defenses and other alcohol-related offenses in Texas.

DWI Attorney for Blood Testing in Houston, Texas

If you or someone you know has been charged with DWI, it’s crucial you seek a skilled criminal defense attorney. You will need strong representation so you can avoid expensive fines and even possible jail time. Call Tyler Flood & Associates, Inc. to speak to an experienced lawyer today.

Our attorneys at Tyler Flood & Associates, Inc. have years of experience with DWI. We can create a sturdy defense plan to protect your freedom. Call (713) 224-5529 to set up a consultation today. Tyler Flood & Associates, Inc. accepts clients throughout the greater Houston metroplex area including Uptown, River Oaks, and Midtown.

This article was last updated on March 13th, 2019.


Use the form to submit your request for a free consultation.

*Use of this form does not constitute an attorney-client relationship.

Driving While Intoxicated (Blood Draw .16)
Client had bond forfeited while case was pending for not being able to attend trial when Judge ordered us to be there due to his teaching job at Texas A&M University. When he finally...read more
Read More Case Results
Tyler Flood & Associates
2019 Washington Ave. #300
Houston, TX 77007
(713) 224-5529
Get Directions to Our Office


Robert Henderson
Robert Henderson
December 22, 2023.
I want to give a special thanks to Tyler Flood & Associates. Getting charged with a dwi was the worst feeling and situation I've been in, but the professionalism and confidence that Tyler Fllod & Associates showed throughout my case definitely helped me get some sleep at night. Then when they called and let me know that my case was dismissed and all charges dropped was incredible. Once again, thanks to Tyler Flood & Associates.
Zeta Ze
Zeta Ze
December 15, 2023.
Houston DWI/DUI Tyler Flood is the best lawyer to represent you in a DWI/DUI case. Mr. Flood saved my license from being suspended in a non-refusal weekend. In a case, where I feel I did everything wrong and had 0 chance, in my opinion, for a dismissal, my only hope and chance was to hire Mr. Flood and his firm. Having had previous experience with Mr. Flood's firm, I felt that if I had any percentage chance of a dismissal, I had to go with Mr. Flood again. As I am writing this review, I'm still in shock and awe in how Mr. Flood was able to get a dismissal before trial completely started. Mr. Flood knew the law better than the arresting officer and Prosecutors. Even the judge was impressed and paid him a compliment after the dismissal. In my opinion, if you want a fighting chance, hire Mr. Flood and his firm. Mr. Flood genuinely cares about all his clients and does not merely see you as a customer. He and his team are always working on your case. Trust his process. They are absolutely the BEST.
briana Munoz
briana Munoz
December 5, 2023.
Thanks to Tyler Flood I am able to continue my life, him and his partners were amazing in guiding me throughout this hard process. Tyler and his team got me a CASE DISMISSED on my DWI case. His team kept in contact with me on every small detail about my case while being able to thoroughly explain every possibility for me. I also never had to step foot in a courtroom! Him and his team had my back every step of the way and never made me feel like it was not going to be okay. Tyler flood is the BEST DWI/DUI attorney no doubt, please consider letting him take your case if you are ever in need of an amazing lawyer.
October 19, 2023.
When I found myself in a precarious situation and didn’t know where or who to turn to I was recommended to Tyler Flood and Associates. After researching and reading many reviews I decided to hire and retain Flood and Associates services. This was one of the best decisions I made in my life, not only were they there for me in every dim moment and never too busy to answer every question I had whether it was frivolous or not, his expertise was demonstrated to me during my trial. So much so that two other defendants asked for his name and number during my trial. He fought tooth-and-nail for me and he will for you too. I’m only rating him five stars because I can’t rate him any higher. I’ll thank him for the rest of my life.
October 12, 2023.
Houston DWI/DUI Attorney Tyler Flood is the best in the business! Tyler and his team made the entire process stress free for what is a very stressful situation. From winning the first administrative hearing (to retain my license/avoid a breathalyzer) to getting the dismissal before trial even started. He is truly the best in the business!
Cesar Ricardez
Cesar Ricardez
October 3, 2023.
I hired Tyler Flood the day after my DUI arrest after reading glowing reviews about him and I couldn’t be happier that I did so. He took care of both my cases to keep my driving rights and the misdemeanor DUI charge in court. I never even had to appear in court or do anything, him and his team took care of anything while I carried on with my life and would just get updates whenever they appeared in court on my behalf. At the end, my driver license was never suspended and they got my case dismissed. Lesson learned, I don’t wish anyone to get in my situation but if you do, don’t hesitate to hire Tyler Flood and his team, they are extremely professional and they go for the win. No deal, no probation, got it all dismissed.
September 14, 2023.
Tyler Flood, Houston DWI/DUI attorney is fantastic! He is professional, smart and takes pride in getting the best possible outcome for you. This was my second DWI and I didn't want to take chances. I found him on Google and I too was in disbelief with all the 5.0 star reviews. Upon meeting him I quickly discovered it was all true. A lawyer with his own science lab WTH??????? Long story short he got my case dismissed without going to court. You can not put a price on freedom. The only downside is I only hope to need his services this one time. 😀 Thanks again Mr. Flood God bless.
John Sellers
John Sellers
August 31, 2023.
Houston DUI/DWI attorney Tyler Flood is the guy to go to!! I started my journey with these guys on August 4th of this year, my case was dismissed before the end of the month!! Well worth it!! They are organized and efficient, kept me informed of what was going on and answered all my questions. I have shared with my friends and definitely recommend to anyone.
August 29, 2023.
Houston DUI/DWI attorney Tyler Flood is an outstanding attorney and person. If you are in need of a lawyer who understands the panic and sheer fear a family feels when this happens in their lives,Tyler Flood is the attorney for you. He has an outstanding educational background, his office includes an on-site, state-of-the-arts laboratory, and he is surrounded with a legal team to provide background and research data for him to be successful in representing you. He is a One-of-Kind, highly accomplished attorney that will promptly respond to you throughout the duration of your case. Seriously, this guy NEVER sleeps! Tyler Flood understands the importance of a person’s reputation and the seriousness of a DUI/DWI charge. If you choose to work with him, he will work with you to be successful! Tyler Flood is AWESOME!
Trey Perrett
Trey Perrett
August 14, 2023.
Words cannot express what a dominating lawyer Tyler Flood and his team are. I ran into some trouble in 2021 and I was just getting my family, career ,and life together. I was completely scared of what the repercussions could be for the rest of my life. I asked civil layers who they recommend and repeatedly Tyler Flood’s name was given to me. At my first appointment, I was overcome with anxiety of what will happen next. Tyler put me at ease immediately. He believed I had a case. They were great on response time and helping me navigate the often confusing legal system. It’s a long process to have a case brought to trial but I knew I had an amazing lawyer and his team in my corner. Finally, I received the call that my case was dismissed, and I was cleared of all charges. I could not be happier with the way he and his colleagues handled my case and brought home the W. I strongly recommend having Tyler Flood in your corner because he delivers.
Disclaimer: The information on this website does NOT constitute legal advice. If you need legal advice, then retain an attorney to discuss the facts of your case. If you would like to discuss your case with an attorney at Tyler Flood & Associates, Inc., then please contact us to schedule a consultation. Until we specifically agree to act for you on a matter, you should not provide us with any confidential information or material.
Copyright © 2024 Tyler Flood & Associates, Inc.
linkedin facebook pinterest youtube rss twitter instagram facebook-blank rss-blank linkedin-blank pinterest youtube twitter instagram