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Notable DWI Victories

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Montgomery County


Attorney: Mark Thiessen

0.112 BLOOD TEST! Client was a young man on his way home, west bound, from a sports bar. Officers had another person pulled over in the east bound lanes. Magnolia PD Officer Landrum wrongfully believed that the client didn’t pull over for their stop. 1. The video showed the client clearly in his west bound lane; 2. You only have to pull over in a lane for an officer on a stop in the same direction of lanes. Officer Landrum had been written up by  plenty of the Montgomery District Attorneys for dishonesty involving their office and DAs. I know this because it was provided to me as Brady notice. Remember, this is a 24 year old man, who has never been arrested a day in his life, has a 0.112 alleged blood score, no accident, with a known lying police officer. The two DAs in the court decided to continue on and try to convict my client. My client’s mother and my intern were in the Court before I got there and heard the DAs say this would be a “good learning experience” because Thiessen was trying the case. Also, the analyst who tested the blood had since stopped testing blood and moved to Colorado. These DAs chose to spend tax payers money on buying her a last minute flight to come down and testify. The trial commenced and I crossed Officer Landrum on the standard field sobriety tests. I showed him medical records of the client’s leg and knee injuries. And we systematically broke down the video so the jury could see how these tests are actually given and their meticulous grading system. The analyst then got on and testified about how she never made mistakes and that her results were reliable and accurate. We brought our own forensic toxicologist, Amanda Culbertson, to show the State and the lab how their own machine pipette was off by more that 10%, the blood was absolutely clotted in the tubes and shouldn’t have been, and that the analyst did not let the vials come to room temperature before preparing the samples. All of these will create false high ethanol levels. The DA and the analyst refused to acknowledge any mistakes. Rather, the DAs objected over 100 times to my evidence, expert, arguments, and even my wanting to show their evidence. The jury of 6 contained 2 federal officers, 1 ex DWI officer from the UK, a lady who was married to a trooper and two people that had no law enforcement ties. Needless to say we were sweating the verdict just based on the composite of the jury. The jury returned a swift verdict of Not Guilty in less than 30 minutes and came out and hugged my client, his mom and myself. The jury could not believe how “aggressive and annoying” (their words not mine) the DAs were in this case. Many times during this case I told the DAs they needed to cut this case or offer something besides a DWI. Around mid-trial when I found out about them saying this was a learning experience I called both of them out and told them how wrong this was to try this case. DAs take an oath to promote justice. This was not justice, this was them playing with a young man’s life and future. This was a particular set of DAs that chose this course. I have let their supervisors and the legal community know. I’m just so thankful to this jury for seeing through their tactics and trickery. They sponsored a lying police officer, they flew in an analyst who was basically a puppet for the State, and then proceeded to object to any evidence of innocence. Montgomery County has some fine DAs, but not these two. I was very worried about this jury being officers, but they showed strength and character and saved our client’s future. We are truly indebted to them and thankful they were there to analyze the evidence and balance the DAs power in this case. Thank you so much to that jury. Y’all really showed me that good police will spot bad police and abuse of power. I am indebted to y’all. Thank you for standing up to the DAs office and demanding better evidence and science.

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Mark Thiessen


DWI, Criminal & Civil Trial Defense Attorney

“I'm a trial-tested Super Lawyer focused on fighting for my client's freedom. If you hire our firm, we're available 24/7, because, at the end of the day, we work for you.”

What to expect?

Thiessen Law Firm. Well-known for both award winning Houston DWI Lawyers and aggressive trial-tested criminal defense techniques, we fight like no other, for your DWI case. Our trial attorneys not only fight for positive results, we also care deeply about the overall well-being of our clients.

Why choose thiessen law?

  • Proven Houston DWI Lawyer
  • Aggressive Defense Attorney
  • Dedicated Team to Fight for You
  • Free Case Evaluation
  • No Hourly Rates
  • 24/7 Accessibility
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Houston DWI & trial attorneys that fight for you in Houston and all Texas counties

Our Houston DWI Attorneys always fight our hardest. We tell the truth about your DWI or DUI case, and facts take precedence over promises. We hold honesty and virtue in highest regard and it is the foundation of ensuring your DWI or criminal case ends with a satisfying, positive outcome.

When you get a DWI, DUI or other criminal charge in Harris County, your life is changed, no matter the verdict. At Thiessen Law Firm, you will be represented by a Houston DWI lawyer who will ensure you’re able to continue on with the life you want. You’ll never feel forced into taking a deal that you don’t want, or accepting terms you don’t fully understand. Mark Thiessen is recognized as an ACS CHAL Lawyer-Scientist for his efforts to understand the science and technology behind DWI testing. This investment in his education and training provides clients with the knowledge needed to fight for their rights effectively and fairly.



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A Citizens Guide to beating a DWI in Texas

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You have 15 days to save your driver's license

Act fast if you've been charged with DWI or DUI in Texas. Here’s something you might not see from other Houston DWI Lawyer websites: If you've been arrested for a DWI or DUI in the state of Texas, you are facing two cases against you. The first one is the criminal case by the state of Texas, and the other is by the Texas Department of Public Safety to suspend your license.

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In The Media

Jurors find woman not guilty of intoxication manslaughter in fatal West Lubbock crash

The defense attorney for a 23-year-old woman said a flawed Lubbock police crash investigation provided enough reasonable doubt for a 12-member jury to find his client not guilty in a fatal 2014 West Lubbock wreck.

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Speaking Engagements

As Houston’s DWI Super Lawyer, Mark Thiessen has consistently set high standards in his field since establishing his firm. His scientific investigation process & comprehensive list of victories has brought him to the forefront of national recognition as he is sought by industry leaders & legal organizations to deliver trial strategy seminars.

Orlando, FL

Florida Bar Association Criminal Law Seminar

Intoxicated Manslaughter

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Dallas, TX

State Bar of Texas Advanced Criminal Law Course

Intoxicated Manslaughter Cases

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Dallas, TX

TCDLA 12th Annual DWI Defense Seminar

Happy Clients

The BEST Attorney in Harris County and Probably One of the Best in the Nation

Mark Thiessen is by far the BEST attorney in Harris County and probably one of the best in the nation. His firm is extremely polite and professional. Mark and his staff were always there for me when I had questions or concerns. He was able to get my DWI dismissed in Harris County which is a huge relief. I would highly recommend Mark for any DWI or drug related case.


DWI client

If You Want a GREAT Lawyer, Mark Thiessen is Your Man

I found Mark Thiessen through several of my friends. I was having serious issues with the lawyer I had at the time. He kept telling me I was going to jail when I had done nothing. He did not believe me, and I believe he was gonna have me put in jail and not fight for my innocence. From the moment I met Mark Thiessen, I knew he was going to do everything for me to keep me from that horrid jail. I was not allowed to leave my county. He drove all the way up to The Woodlands to meet me at Starbucks to speak on my case. He got all the charges against me dropped within minutes. He’s truly the best lawyer. He has a lot of respect from his piers including the judge that actually told me I was very lucky to have such a great lawyer. And trust me, I know I was lucky to have found him, and that is the gods honest truth. If you want a GREAT lawyer, Mark Thiessen is your man.


DWI Client

The Best Lawyer in the Industry

I chose Mark Thiessen to represent me in a DUI / DWI case and it was the best selection/decision that I could have made. I found out about Mark through Internet search and reached out to him and his office. Upon meeting with Mark – I immediately knew that he was the right lawyer/attorney to represent me and give me the best opportunity to win my case. Mark is an expert attorney with a work ethic that is second to none. He is always available. He is a master of his craft and will give you the best opportunity to win your case. He will be prepared and he will do everything to ensure your case is won. He will actually be more knowledgable on the aspects of law, facts of the case, than the individuals that have accused you of your offense. He was highly successful in my case, even despite some of the alleged facts not being in my favor. We won the case and all charges were dropped. Thanks Mark!


DWI Client

Fantastic Lawyer

I would HIGHLY recommend hiring Mark Thiessen as your attorney for any criminal case that you have received in the Harris County area. He is extremely knowledgeable of the court system and what actions can be taken pre-trial in order to have the best outcome at your court date. I was put on probation for a DWI a year previous to hiring Mark as my attorney. I failed to complete the requirements in order to get off of probation. My probation was revoked and sent back to the courts. That’s when I hired Mark. He told me to go complete the rest of the requirements for probation and get myself a court date. When we got to court he persuaded the judge not only to dismiss my probation, but dismiss it successfully. In court he made small talk with the judge and prosecutor which told me that he knew them and had a good relationship with them. Which was not the case for other attorneys that went in front of this judge. Again you can’t go wrong hiring Mark. He is great attorney and great person.


DWI Client

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aggressive defense