Biography

Mark Thissen

DWI, Criminal, and Civil Trial Attorney

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 quadruple intoxication manslaughter. Mark has earned formidable reputation for being a tenacious trial lawyer, and he works hard to maintain that status.

Since opening Thiessen Law Firm, Mark has continued to add to his growing list of accomplishments. Mark Thiessen was the youngest criminal Super Lawyer in Texas in 2013. As of 2018, Mark is Board Certified in Criminal Law by the Texas Board of Legal Specialization. He has 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 is a 6 time Texas Super Lawyer and in the Top 100 Super Lawyers in Houston (2017 & 18). In 2019, Mark was the only criminal lawyer to be named to the Top 100 Super Lawyers in all of Texas. As of 2020, Mark is also Board Certified in DWI Defense by the National College for DUI Defense.

Mark is also a frequent legal seminar lecturer, author of numerous published legal articles, and a faculty member for various organizations.



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 maintains an emphasis on 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.

Mark is the current DWI Committee co-chair and on the Board of Directors for the Texas Criminal Defense Lawyers Association (TCDLA), President-Elect 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 for fearlessness extends beyond his presence in the courtroom. In his free time, he competes in Brazilian jiu-jitsu as a brown belt, Muay Thai, and participates in competitions such as the Warrior Dash and Tough Mudder. Most of all, 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.

Honors View all

Media And Justice for None: How COVID-19 is Crippling the Criminal Jury Right Turnout for grand jury selection drops during pandemic View all

Speaking Engagements 06.05.20 Austin, TX TCCLA CLE Speaker’s Luncheon New Advances in DWI Law 04.18.20 Washington D.C. Supreme Trial Tactics DUIDLA Spring Seminar 04.16.20 Ft. Worth, TX Texas Family Bar CLE Problems with Scientific Devices 03.30.20 Huntsville, TX TCDLA Tim Evans’ Trial College Trial Tactics for Beginning Lawyers 03.12.20 Columbia, OH OACDL Advanced Criminal Law Defending Intoxicated Manslaughter Cases 02.26.20 Houston, TX STCL Prof. Moses’ Voir Dire and Opening Class Trial Tactics from the Trenches 02.03.20 The Caribbean TCDLA President’s Trip Cruising While Intoxicated 11.08.19 Columbia, SC Top Tips for DWI Trials SCACDL Reese Joye DUI Seminar 09.20.19 San Diego, CA DUIDLA Fall Seminar Defending BWI Cases 09.13.19 Orlando, FL Florida Bar Association Criminal Law Seminar Intoxicated Manslaughter 08.05.19 Houston, TX CCCL Judicial Education Conference Current Updates on DWI Issues 07.23.19 Dallas, TX State Bar of Texas Advanced Criminal Law Course Intoxicated Manslaughter Cases 06.14.19 San Antonio, TX TCDLA 32nd Annual Rusty Duncan Advanced Criminal Law Seminar Intoxilyzer 9000 and NEW Defenses 05.03.19 Dallas, TX TCDLA 12th Annual DWI Defense Seminar 03.27.19 Houston, TX STCL Professor Moses’ Class on Openings and Closings 03.25.19 Huntsville, TX TCDLA Trial College Closing Arguments 01.25.19 Austin, TX TCDLA 6th Annual Lonestar DWI Forensics BWI Defenses 10.17.18 Austin, TX State Bar of Texas Handling Your First (or Next) DWI Case: Handling Breath/Blood Test Analysts 10.17.18 Round Top, TX TCDLA Round Top VIII Advanced Skills Training Psychodrama in DWI Cases 10.12.18 Austin, TX TCDLA 16th Annual Forensics Seminar Accident Reconstruction 10.04.18 Houston, TX Harris County Public Defenders Office CLE Defending Intoxication Related Crimes 09.20.18 Philadelphia, PA DUIDLA Fall Seminar 2018 Not Guilty v. Cerberus; Beating Intoxicated Manslaughter Cases 08.17.18 Houston, TX TCDLA Top Gun DWI Seminar Top 10 DWI Trial Tactics to Shooting Down the State’s Case 06.28.18 San Antonio, Texas TCDLA Rusty Duncan Seminar Not Guilty v Cerberus: Beating Intox Manslaughter Cases 03.27.18 Huntsville, TX TCDLA 42nd Annual Tim Evans Trial College Instructor 01.26.18 Austin, TX TCDLA Lone Star DWI TIED FOR #1 SPEAKER: Beating Intoxicated Manslaughter Cases: Not Guilty v Cerberus 01.05.18 Lubbock, TX TCDLA Prairie Dog Seminar Attacking Blood Labs and Beating Intoxicated Manslaughter Cases 09.14.17 Charleston, NC DUIDLA: Fall Seminar Voir Dire & Cross in Blood Test Cases 08.18.17 Houston, TX TDLA Top Gun DWI Seminar Speaking with DA on DWI Trial Tactics. Voted #1 Speaker for this speaking engagement 08.09.17 Houston, TX HYLA How to Successfully Start and Manage a Law Firm 07.18.17 Houston, TX State Bar of Texas Advanced Criminal Law Seminar: Intoxilyzer 9000 06.23.17 San Antonio, TX TCDLA 30th Annual Rusty Duncan Advanced Criminal Law Intoxilyzer 9000 04.12.17 Houston, TX South Texas College of Law Professor Moses’ Openings and Closings Class: DWI Trial Tactics 04.07.17 Houston, TX TCDLA Training Day CLE: DWI Pretrial Motions to Suppress 03.10.17 Columbus, OH Ohio Association of Criminal Defense Lawyers Best in the Midwest Ohio Advanced DUI Seminar- Defense v. Prosecution DWI Techniques 02.13.17 Caribbean Sea TCDLA President’s Cruise CLE: Attacking the Drug Recognition Expert 01.13.17 Lubbock, TX TCDLA Prairie Dog Seminar Attacking the DRE Expert 11.11.16 San Antonio, TX Stuart Kinard Memorial Advanced DWI Seminar TIED FOR #1 SPEAKER: Defense v. DA Trial Tactics with Bexar County DA Nico LaHood 11.03.16 San Antonio, TX TCDLA Stuart Kinard Advanced DWI Seminar Speaking with Bexar County District Attorney Nico Lahood on DWI trial strategies from both sides 10.13.16 Tunica, MS Tennessee Association of Criminal Defense Lawyers Annual DUI Seminar and Training Not Guilty v. Goliath; Taking Down High Blood Tests Using the Disconnect Defense. 09.16.16 Houston, TX TCDLA Top Gun DWI Intoxilyzer 9000 08.26.16 San Antonio, TX SACDLA Seminar Intoxication Manslaughter Trial Tactics 07.22.16 Austin, TX TCDLA 3rd Annual Lonestar DWI TIED FOR #1 SPEAKER: Candida Albicans and the Autobrewery Syndrome 07.20.16 Dallas, TX State Bar of Texas 42nd Annual Advanced Criminal Law Seminar DWI Trial Tactics and Case Law Update 06.17.16 San Antonio, TX TCDLA 29th Annual Rusty Duncan Seminar TIED FOR #1 SPEAKER: DWI Voir Dire From Full Refusals to Intoxicated Manslaughter 05.20.16 Salt Lake City, UT Utah Association of Criminal Defense Lawyers Advanced DWI Seminar Not Guilty v. Goliath, Taking Down High Blood Tests Without an Expert 05.06.16 San Antonio, TX TCDLA DWI Defense Project DWI Blood Cross-Examination 04.16.16 San Antonio, TX TCDLA, SACDLA, SABA 53rd Annual Anees Semaan Advanced Criminal Law Seminar DWI Voir Dire From Full Refusals to Intoxicated Manslaughter 03.11.16 Columbus, OH Ohio Association of Criminal Defense Lawyers Best in the Midwest Not Guilty Versus Goliath; Taking Down High Blood Tests Using the Disconnect Defense 01.22.16 College Station, TX TCDLA Upholding Justice One Client at a Time VOTED #1 SPEAKER: DWI Techniques 11.13.15 San Antonio, TX TCDLA Stuart Kinard Memorial Advanced DWI Seminar Attacking the DRE Expert 10.03.15 Little Rock, AR Pulaski County Bar Association – DWI Institute: My Case is a Wreck Not Guilty v. Goliath & DWI Blood Test Disconnect Defense 07.17.15 Austin, TX TCDLA 2nd Annual Lone Star DWI: Drugs DWI Hallucinogens and Stimulants & Intoxilyzer 9000 07.10.15 Chicago, IL DUIDLA Blood Test Disconnect Defence and Cross Examination Techniques 06.19.15 San Antonio, TX 28th Annual TCDLA Rusty Duncan Seminar Blood Testing Science and Case Law 05.01.15 Arlington, TX TCDLA DWI Defense Project TIED FOR #1 SPEAKER: Cross Examination of the Blood Analyst 04.18.15 San Antonio, TX TCDLA, SACDLA, SABA 52nd Annual Anees Semaan Advanced Criminal Law Seminar Not Guilty v. Goliath; Taking Down High Blood Tests Using the Disconnect Defense 04.17.15 Waco, TX TCDLA Training Your Defense Team to Win Jury Selection 01.09.15 Lubbock, TX Annual Prairie Dog Advanced Criminal Law TIED FOR #1 SPEAKER: Not Guilty v. Goliath; Taking Down High Blood Tests Using the Disconnect Defense 12.11.14 Denton, TX Jolly Roger Seminar DWI Blood Trial Tactics 11.07.14 San Antonio, TX 2014 Stuart Kinard Memorial Advanced DWI Seminar VOTED #1 SPEAKER: Not Guilty vs. Goliath, Taking Down High Blood Tests with the Disconnect Defense 09.12.14 Dallas, TX TCDLA: Cross Examination TIED FOR #1 SPEAKER: Cross of DWI Blood Expert 08.22.14 Houston, TX TCDLA: Top Gun DWI Seminar Blood Test Voir Dire & Preparing the Jury for Acquittal 07.18.14 South Padre Island, TX TCDLA Member’s Trip VOTED #1 SPEAKER: Not Guilty vs Goliath & Taking Down High Blood Tests Using the Disconnect Defense 07.11.14 Austin, TX TCDLA Lone Star DWI VOTED #1 SPEAKER: Blood 101: Basics of Blood Testing & Taking Down High Blood Tests Using the Disconnect Defense 06.13.14 San Antonio, TX 27th Annual TCDLA Rusty Duncan Advanced Criminal Law Course DWI Blood Testing Basic; What Works and What Doesn\'t 05.09.14 Humble, TX Houston Bar Association at Summer Creek High School Sex, Drugs and Alcohol; Keeping Kids Scared Straight 04.25.14 Longview, TX TCDLA Trial Strategies that Work VOTED #1 SPEAKER: Opening and Closing Statement 02.23.14 Houston, TX Harris County Municipal Justice Bar Association Annual CLE Trial Tactics From the Trenches 02.21.14 Houston, TX Third Annual Hon. Craig Washington & Sen. Rodney Ellis Criminal Law Seminar Advanced Trial Techniques 01.09.14 Lubbock, TX TCDLA 33rd Annual Prairie Dog Lawyers Advanced Criminal Law Basics of Blood Testing to Taking Down Big Blood Tests; How We Do It 11.22.13 Humble, TX Houston Bar Association at Summer Creek High School Knowing Your Rights; Sex, Drugs, DWI and Assault 11.07.13 Houston, TX Houston Bar Association at Westside High School Mock Trial Voir Dire 10.17.13 Houston, TX TCDLA / Public Defender’s Office Indigent Defense Advanced Trial Tactics 08.23.13 Houston, TX TCDLA Top Gun DWI 10 Silver Bullets for DWI Trials 07.12.13 South Padre Island, TX TCDLA Gideon’s Trumpet Seminar Series Basics of Blood Testing; Attacking a DWI Blood Test 05.13.13 Houston, TX HCCLA Training Day: Criminal Law 101 Trial Tactics from the Trenches 05.03.13 Arlington, TX TCDLA DWI Defense Project Basics of Blood Testing; Attacking a DWI Blood Test 04.26.13 Houston, TX Harris County Public Defender Closing Arguments – Storytelling 04.19.13 Waco, TX TCDLA Gideon’s Trumpet Seminar Series Basics of Blood Testing; Attacking a DWI Blood Test 04.09.13 Humble, TX Houston Bar Association at Summer Creek High School Knowing Your Rights; Sex, Drugs, DWI and Assault 03.01.13 Houston, TX Harris County Public Defender Closing Arguments – Storytelling 02.15.13 Houston, TX Westlaw Ed. Center National Webinar Basics of Blood Testing; Attacking a DWI Blood Test 02.15.13 Houston, TX Houston Bar Association Trial Tactics from the Criminal Trenches 01.11.13 Lubbock, TX TCDLA 32nd Annual Prairie Dog Lawyers Advanced Criminal Law Basics of Blood Testing; Attacking a DWI Blood Test 11.13.12 Humble, TX Houston Bar Association at Summer Creek High School The Importance of Jury Service and Knowing the Law 09.21.12 Georgetown, TX TCDLA Gideon’s Trumpet Seminar Series Basics of Blood Testing; Attacking a DWI Blood Test 08.19.12 Houston, TX TSU Thurgood Marshall School of Law Criminal Trial Clinic – DWI Trial Tactics and Voir Dire 08.17.12 Austin, TX TCDLA TOP GUN DWI Seminar Cross-Examination of Breath Test Technical Supervisor 05.17.12 Houston, TX Harris County Criminal Lawyers Association CLE Trial Tactics from the Trenches 02.09.12 Dallas, TX TCDLA Boot Camp for Young Lawyers DWI Trial Tactics and Skills 01.12.12 Houston, TX TSU Thurgood Marshall School of Law DWI Nuts and Bolts – DWI Voir Dire on High Breath Test with Accident 12.01.11 Houston, TX TCDLA Voir Dire Seminar Car Accidents and Hospital Enzymatic Assay Blood Testing 08.11.11 Houston, TX Texas Criminal Defense Lawyers Assoc.’s Top Gun DWI Seminar Final Argument 07.15.11 South Padre Island, TX TCDLA Art of War Trial Tactics The Game of Trial; Running the Bases 04.20.11 Houston, TX South Texas College of Law Advanced Advocacy Class The Game of Trial; Running the Bases 04.14.11 Tyler, TX TCDLA Art of War Trial Tactics The Game of Trial; Running the Bases 01.28.11 Edinburg, TX TCDLA Art of War Trial Tactics The Game of Trial; Running the Bases 11.18.10 San Antonio, TX 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 09.02.10 Houston, TX Network of Professional Brazilians in Houston Understanding Your Rights in Texas and Secrets to Avoiding a DWI Arrest and Conviction 04.07.10 Houston, TX North Shore Senior High School Keeping Students Safe from DWI and Drugs 03.19.10 Galveston, TX Galveston County Criminal Defense Lawyers Assoc. CLE TIMBER! Chopping Down High Breath Tests 12.09.09 Conroe, TX Montgomery County Criminal Defense Lawyers Assoc. CLE New Issues in Montgomery County – Death to the \"E\" Jury; Getting a Fair Trial 05.08.09 Dallas, TX David Burrows DWI Defense Project The Game of Trial; Running the Bases View all