Mark Ryan Thiessen

Mark Thiessen is a criminal trial lawyer and the Chairman/CEO of the Thiessen Law Firm in Houston, Texas. Mark is Board Certified in Criminal Law by the Texas Board of Legal Specialization and Board Certified in DUI Law by the DUI Defense Lawyers Association. Mark earned the American Chemical Society-Chemistry and the Law (ACS-CHAL) Forensic Lawyer-Scientist designation, which is the highest form of scientific recognition available for lawyers. Mark is a frequent legal seminar lecturer, author of numerous published legal articles, and a faculty member for various organizations. Mark is the current DWI Committee co-chair and on the Board of Directors for Texas Criminal Defense Lawyers Association (TCDLA), on the Board of Directors for Harris County Criminal Lawyers Association (HCCLA) and a Charter Member and Director for DUI Defense Lawyers Association (DUIDLA). 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. Mark has won DWI cases from total refusals up to quadruple intoxication manslaughter.

Mark’s reputation for fearlessness extends beyond his presence in the courtroom. In his free time, he competes as a Brown Belt in Brazilian jiu-jitsu, Muay Thai, and participates in competitions such as the Warrior Dash and Tough Mudder. He is also an avid snow skier, wake boarder and tennis player.