DWI & Criminal Law Specialist
Mark Thiessen prides himself on being an aggressive trial lawyer. If the district attorney will not bargain or justice will not be served by allowing the client to plead guilty, Mark passionately and professionally represents his clients at trial. He has won DWI cases from total refusals up to triple intoxication manslaughter. Mark has earned formidable reputation for being a tenacious Houston DWI trial lawyer, and he works hard to maintain that status. Mark is licensed and tries cases in Texas and Colorado.
Since opening Thiessen Law Firm, Mark has continued to add to his growing list of accomplishments. In addition to his widely publicized feats as a winning Houston intoxication manslaughter lawyer, Mark Thiessen was the youngest criminal Super Lawyer in Texas in 2013. As of 2024, Mark is a 13 time Texas Super Lawyer, 9 time Top 100 Super Lawyers in Houston and 6 time Top 100 Super Lawyers in all of Texas. For four years, Mark has been the only DWI lawyer listed in the Top 100 in Houston and the only DWI Specialist Super Lawyer listed in the Top 100 Lawyers in Texas.
Mark is the only lawyer in America who is 3x board certified in:
- Criminal Law by the Texas Board of Legal Specialization
- DUI Defense by the National College for DUI Defense as approved through the American Bar Association
- DUI Law by the DUI Defense Lawyers Association
- Board Certified Advocate Criminal Trial Law by the NBTA Foundation
Mark has also earned the American Chemical Society-Chemistry and the Law’s (ACS-CHAL) Forensic Lawyer-Scientist designation — the highest form of scientific recognition available for lawyers.
Mark has expanded his firm’s leadership into the following practice areas:
- Houston DWI lawyer
- Intoxication manslaughter lawyer in Houston
- Houston assault lawyer
- Aggravated assault lawyer in Houston
- Houston drug lawyer
- Houston car accident and truck accident lawyer
- Houston personal injury attorney
Mark is also a frequent legal seminar lecturer, author of numerous published legal articles, and a faculty member for various organizations. Mark is an international lecturer and is regularly called on to speak and educate students, police officers, lawyers and judges.
Mark Thiessen was born and raised in Houston, Texas. Mark attended the Village School and St. Francis Episcopal Middle School before graduating from the Kinkaid School in 1996. Mr. Thiessen then attended and graduated from Texas Christian University in 2000 with a Bachelor’s of Business Administration in Marketing. While at TCU, Mark was a member of Phi Delta Theta fraternity and on the dean’s list.
Following his time at TCU, Mr. Thiessen returned to Houston and began his law school education at South Texas College of Law (STCL). Mark made the most of his time at STCL, actively taking part in mock trials and campus law societies. Mark’s passion for the law also took him abroad: he has studied at the International Criminal Law at the University of Malta, the BPP Law School in London, England, and at the University of Hawaii. Studying in these unique legal environments required Mark to adapt to various social, cultural, ethnic, and economic groups, which is evident in his approach and personality to this day.
After graduating from law school, Mark practiced civil law at Bell, Ryniker & Letourneau and at Brown Sims, P.C. In 2006, he followed his passion for criminal law by joining the team at Trichter & Murphy, P.C., where Mark was able to study under some of the foremost legal authorities in Texas. After five years with Trichter & Murphy, P.C., Mark decided to start his own law firm, thus opening Thiessen Law Firm.
Although his practice includes all areas of criminal defense, Mr. Thiessen specializes in cases regarding DWI, drugs, and controlled substances. The trial of a DWI case dictates that, on any given date, a trial lawyer must be not only well-versed in Rules of Evidence, case law pertaining to DWIs, and constitutional law, but also numerous areas of science such as anatomy, physiology, toxicology, chemistry, computer science, biology, and physics. Additionally, Mark has studied many hours of trial strategies in order to properly educate jurors and judges on the sciences involved.
Mark is the current DWI Committee co-chair and on the Board of Directors for the Texas Criminal Defense Lawyers Association (TCDLA), the 50th President and on the Board of Directors for Harris County Criminal Lawyers Association (HCCLA) and a Charter Member and Treasurer and Director for DUI Defense Lawyers Association (DUIDLA).
Mark’s reputation as a fearless, famous Houston attorney extends beyond his presence in the courtroom. In his free time, he competes in Brazilian jiu-jitsu as a black belt for Brazil-021 School of Jiu Jitsu in Houston and also trains Muay Thai. Mark is an avid snow skier, tennis player and waterman. But above all else, he loves going on adventures with his family.
If you have a case and want an attorney who does not back down, call Mr. Thiessen today: 713-864-9000.
Publications
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Drunk Houston woman Kristina Chambers plows Porsche into man on first date, killing him: cops
Press Releases
Houston Attorney Mark Thiessen Wins Ninth Consecutive Super Lawyer Award, Ranks Among the Top 100 Lawyers in Texas
Criminal Court Reopening and Public Health in the COVID-19 Era
Speaking Engagements
TCDLA Top Gun Advanced DWI CLE – Breaking Down Blood Testing for Lawyers
State Bar of Texas Advanced Criminal Law CLE – Cross Examining the SFSTs
Harris County Managed Assigned Counsel (MAC)/ SFSTs and the Disconnect Defense
South Texas College of Law Criminal Law Society/ Criminal Law Primer
TCDLA Intoxication Manslaughter CLE
Voir Dire
TACDL Masters of DUI Seminar
Images, Analogies, and Stories
DUIDLA Fall Seminar
Past, Present, and Future of DUI
TCDLA 36th Annual Rusty Duncan Advanced Criminal Law Seminar
Images, Analogies, and Stories
FACDL Masters of DUI
Blood Test Cross Examination Techniques
DUIDLA Spring Seminar
Science in Bite Sized Chunks
Harris County Public Defender’s Office
Blood Test Cross Examination Techniques
Houston Managed Assigned Counsel Training
Disconnect and SFSTS and Blood Test Cross Exam
TCDLA President’s Trip
Almost Everything You Need to Win DWI Trials
TCDLA 42nd Annual Prairie Dog Advanced Criminal Law Seminar
Almost Everything You Need to Win DWI Trials
NHACDL Criminal Law Seminar
Images, Analogies, and Stories
FACDL Blood Breath and Tears
Defending BWI Cases and Mock Trial
ACDLA DWI Seminar
10 Easy Tips for Winning DWI Trials
DUIDLA Fall Seminar
Back to the Basics
TCDLA 30th Annual Top Gun
Beating Blood and Breath Through the Officer
California Defense Lawyers Assoc.; 2022 Annual Kuwatch Conference
Top 10 DWI Trial Tactics
Harris County Institute of Forensic Sciences (HCIFS); 2022 Topics in Forensic Science (TIFS) Conference
Defense Perspectives in DUI/D Litigation
The Florida Bar; Masters of DUI
Not Guilty v. Goliath, Taking Down High Blood Tests
SACDLA/TCDLA 4th Annual Fiesta 2022 Advanced Criminal Defense Seminar
New Defenses to the Intoxilyzer 9000
DUIDLA Spring SeminarCriminal Defense Seminar
Cross Examining the Blood Expert
TCDLA Lonestar DWI
Understanding and Beating the Intoxilyzer 9000
Texas Tech University – Criminal Law Class
Trial Tactics from the Trenches
State Bar of Texas – Firearms Law
Trial Strategy and Cross Exam of Arresting Officer
TCDLA Trial College
Opening and Direct Examination
TCDLA/SACDLA Fiesta Seminar
Updating Blood Vial Scandal Information
TCDLA 34th Annual Rusty Duncan Advanced Criminal Law
DWI Update Post-Covid
TCDLA 14th Annual DWI Defense Project
Attacking SFSTs
State Bar of Texas – Marriage Dissolution Institute
Dragnet: Drug & Alcohol Testing & Devices That Actually Work
TCDLA 8th Annual Lonestar DWI
Closing Arguments and Story Telling
TCDLA 40th Annual Prairie Dog Criminal Law CLE
DWI Updates and Development
DUIDLA COVID Panel
Trying Cases in Covid Times
DUIDLA Fall Seminar
Perfecting the Disconnect Defense
ICDLA Indiana Public Defender CLE
DWI Pretrial Motions/
TCDLA 18th Annual Top Gun DWI Seminar
DWI Voir Dire
State Bar of Texas Advanced Criminal Law
Back to the Basics; Attacking SFSTs
TCCLA CLE Speaker’s Luncheon
New Advances in DWI Law
Texas Family Bar CLE
Problems with Scientific Devices
TCDLA Tim Evans’ Trial College
Trial Tactics for Beginning Lawyers
OACDL Advanced Criminal Law
Defending Intoxicated Manslaughter Cases
STCL Prof. Moses’ Voir Dire and Opening Class
Trial Tactics from the Trenches
TCDLA President’s Trip
Cruising While Intoxicated
Top Tips for DWI Trials
SCACDL Reese Joye DUI Seminar
Supreme Trial Tactics
DUIDLA Spring Seminar
TCDLA Prairie Dog Seminar
Attacking Blood Labs and Beating Intoxicated Manslaughter Cases
DUIDLA: Fall Seminar
Voir Dire & Cross in Blood Test Cases
TDLA Top Gun DWI Seminar
Speaking with DA on DWI Trial Tactics. Voted #1 Speaker for this speaking engagement
HYLA
How to Successfully Start and Manage a Law Firm
State Bar of Texas
Advanced Criminal Law Seminar: Intoxilyzer 9000
TCDLA 30th Annual Rusty Duncan Advanced Criminal Law
Intoxilyzer 9000
South Texas College of Law
Professor Moses’ Openings and Closings Class: DWI Trial Tactics
TCDLA Training Day
CLE: DWI Pretrial Motions to Suppress
Ohio Association of Criminal Defense Lawyers Best in the Midwest
Ohio Advanced DUI Seminar- Defense v. Prosecution DWI Techniques
TCDLA President’s Cruise
CLE: Attacking the Drug Recognition Expert
TCDLA Prairie Dog Seminar
Attacking the DRE Expert
Stuart Kinard Memorial Advanced DWI Seminar
TIED FOR #1 SPEAKER: Defense v. DA Trial Tactics with Bexar County DA Nico LaHood
TCDLA Stuart Kinard Advanced DWI Seminar
Speaking with Bexar County District Attorney Nico Lahood on DWI trial strategies from both sides
Tennessee Association of Criminal Defense Lawyers Annual DUI Seminar and Training
Not Guilty v. Goliath; Taking Down High Blood Tests Using the Disconnect Defense.
TCDLA Top Gun DWI
Intoxilyzer 9000
SACDLA Seminar
Intoxication Manslaughter Trial Tactics
TCDLA 3rd Annual Lonestar DWI
TIED FOR #1 SPEAKER: Candida Albicans and the Autobrewery Syndrome
State Bar of Texas 42nd Annual Advanced Criminal Law Seminar
DWI Trial Tactics and Case Law Update
TCDLA 29th Annual Rusty Duncan Seminar
TIED FOR #1 SPEAKER: DWI Voir Dire From Full Refusals to Intoxicated Manslaughter
Utah Association of Criminal Defense Lawyers Advanced DWI Seminar
Not Guilty v. Goliath, Taking Down High Blood Tests Without an Expert
TCDLA DWI Defense Project
DWI Blood Cross-Examination
TCDLA, SACDLA, SABA 53rd Annual Anees Semaan Advanced Criminal Law Seminar
DWI Voir Dire From Full Refusals to Intoxicated Manslaughter
Ohio Association of Criminal Defense Lawyers Best in the Midwest
Not Guilty Versus Goliath; Taking Down High Blood Tests Using the Disconnect Defense
TCDLA Upholding Justice One Client at a Time
VOTED #1 SPEAKER: DWI Techniques
TCDLA Stuart Kinard Memorial Advanced DWI Seminar
Attacking the DRE Expert
Pulaski County Bar Association – DWI Institute: My Case is a Wreck
Not Guilty v. Goliath & DWI Blood Test Disconnect Defense
TCDLA 2nd Annual Lone Star DWI: Drugs
DWI Hallucinogens and Stimulants & Intoxilyzer 9000
DUIDLA
Blood Test Disconnect Defence and Cross Examination Techniques
28th Annual TCDLA Rusty Duncan Seminar
Blood Testing Science and Case Law
TCDLA DWI Defense Project
TIED FOR #1 SPEAKER: Cross Examination of the Blood Analyst
TCDLA, SACDLA, SABA 52nd Annual Anees Semaan Advanced Criminal Law Seminar
Not Guilty v. Goliath; Taking Down High Blood Tests Using the Disconnect Defense
TCDLA Training Your Defense Team to Win
Jury Selection
Annual Prairie Dog Advanced Criminal Law
TIED FOR #1 SPEAKER: Not Guilty v. Goliath; Taking Down High Blood Tests Using the Disconnect Defense
Jolly Roger Seminar
DWI Blood Trial Tactics
2014 Stuart Kinard Memorial Advanced DWI Seminar
VOTED #1 SPEAKER: Not Guilty vs. Goliath, Taking Down High Blood Tests with the Disconnect Defense
TCDLA: Cross Examination
TIED FOR #1 SPEAKER: Cross of DWI Blood Expert
TCDLA: Top Gun DWI Seminar
Blood Test Voir Dire & Preparing the Jury for Acquittal
TCDLA Member’s Trip
VOTED #1 SPEAKER: Not Guilty vs Goliath & Taking Down High Blood Tests Using the Disconnect Defense
TCDLA Lone Star DWI
VOTED #1 SPEAKER: Blood 101: Basics of Blood Testing & Taking Down High Blood Tests Using the Disconnect Defense
27th Annual TCDLA Rusty Duncan Advanced Criminal Law Course
DWI Blood Testing Basic; What Works and What Doesn\'t
Houston Bar Association at Summer Creek High School
Sex, Drugs and Alcohol; Keeping Kids Scared Straight
TCDLA Trial Strategies that Work
VOTED #1 SPEAKER: Opening and Closing Statement
Harris County Municipal Justice Bar Association Annual CLE
Trial Tactics From the Trenches
Third Annual Hon. Craig Washington & Sen. Rodney Ellis Criminal Law Seminar
Advanced Trial Techniques
TCDLA 33rd Annual Prairie Dog Lawyers Advanced Criminal Law
Basics of Blood Testing to Taking Down Big Blood Tests; How We Do It
Houston Bar Association at Summer Creek High School
Knowing Your Rights; Sex, Drugs, DWI and Assault
Houston Bar Association at Westside High School
Mock Trial Voir Dire
TCDLA / Public Defender’s Office
Indigent Defense Advanced Trial Tactics
TCDLA Top Gun DWI
10 Silver Bullets for DWI Trials
TCDLA Gideon’s Trumpet Seminar Series
Basics of Blood Testing; Attacking a DWI Blood Test
HCCLA Training Day: Criminal Law 101
Trial Tactics from the Trenches
TCDLA DWI Defense Project
Basics of Blood Testing; Attacking a DWI Blood Test
Harris County Public Defender
Closing Arguments – Storytelling
TCDLA Gideon’s Trumpet Seminar Series
Basics of Blood Testing; Attacking a DWI Blood Test
Houston Bar Association at Summer Creek High School
Knowing Your Rights; Sex, Drugs, DWI and Assault
Harris County Public Defender
Closing Arguments – Storytelling
Houston Bar Association
Trial Tactics from the Criminal Trenches
Westlaw Ed. Center National Webinar
Basics of Blood Testing; Attacking a DWI Blood Test
TCDLA 32nd Annual Prairie Dog Lawyers Advanced Criminal Law
Basics of Blood Testing; Attacking a DWI Blood Test
Houston Bar Association at Summer Creek High School
The Importance of Jury Service and Knowing the Law
TCDLA Gideon’s Trumpet Seminar Series
Basics of Blood Testing; Attacking a DWI Blood Test
TSU Thurgood Marshall School of Law
Criminal Trial Clinic – DWI Trial Tactics and Voir Dire
TCDLA TOP GUN DWI Seminar
Cross-Examination of Breath Test Technical Supervisor
Harris County Criminal Lawyers Association CLE
Trial Tactics from the Trenches
TCDLA Boot Camp for Young Lawyers
DWI Trial Tactics and Skills
TSU Thurgood Marshall School of Law
DWI Nuts and Bolts – DWI Voir Dire on High Breath Test with Accident
TCDLA Voir Dire Seminar
Car Accidents and Hospital Enzymatic Assay Blood Testing
Texas Criminal Defense Lawyers Assoc.’s Top Gun DWI Seminar
Final Argument
TCDLA Art of War Trial Tactics
The Game of Trial; Running the Bases
South Texas College of Law Advanced Advocacy Class
The Game of Trial; Running the Bases
TCDLA Art of War Trial Tactics
The Game of Trial; Running the Bases
TCDLA Art of War Trial Tactics
The Game of Trial; Running the Bases
National College of DUI Defense/Texas Criminal Defense Lawyers Assoc.’s Stuart Kinard Advanced DWI Seminar
TIMBER! Chopping Down High Breath Tests without an Expert
Network of Professional Brazilians in Houston
Understanding Your Rights in Texas and Secrets to Avoiding a DWI Arrest and Conviction
North Shore Senior High School
Keeping Students Safe from DWI and Drugs
Galveston County Criminal Defense Lawyers Assoc. CLE
TIMBER! Chopping Down High Breath Tests
Montgomery County Criminal Defense Lawyers Assoc. CLE
New Issues in Montgomery County – Death to the \"E\" Jury; Getting a Fair Trial
David Burrows DWI Defense Project
The Game of Trial; Running the Bases
TCDLA Lone Star DWI
TIED FOR #1 SPEAKER: Beating Intoxicated Manslaughter Cases: Not Guilty v Cerberus
TCDLA Rusty Duncan Seminar
Not Guilty v Cerberus: Beating Intox Manslaughter Cases
TCDLA Top Gun DWI Seminar
Top 10 DWI Trial Tactics to Shooting Down the State’s Case
DUIDLA Fall Seminar 2018
Not Guilty v. Cerberus; Beating Intoxicated Manslaughter Cases
State Bar of Texas
Handling Your First (or Next) DWI Case: Handling Breath/Blood Test Analysts
Harris County Public Defenders Office CLE
Defending Intoxication Related Crimes
TCDLA 16th Annual Forensics Seminar
Accident Reconstruction
TCDLA Round Top VIII Advanced Skills Training
Psychodrama in DWI Cases
TCDLA 6th Annual Lonestar DWI Forensics
BWI Defenses
TCDLA 42nd Annual Tim Evans Trial College
Instructor
TCDLA Trial College
Closing Arguments
STCL Professor Moses’ Class on Openings and Closings
TCDLA 12th Annual DWI Defense Seminar
State Bar of Texas Advanced Criminal Law Course
Intoxicated Manslaughter Cases
Florida Bar Association Criminal Law Seminar
Intoxicated Manslaughter
TCDLA 32nd Annual Rusty Duncan Advanced Criminal Law Seminar
Intoxilyzer 9000 and NEW Defenses
CCCL Judicial Education Conference
Current Updates on DWI Issues
DUIDLA Fall Seminar
Defending BWI Cases
