Mark Thiessen

Thiessen Law Firm
733 E 12th 1/2 St
Houston, TX 77008

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 Houston DWI 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. 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 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. In addition to DWI, he has also expanded his firm’s leadership into additional practice areas, including:

Houston BWI
Houston drug lawyer
Houston child custody
Father’s rights in Houston, Texas
Houston juvenile lawyer
Aggravated assault lawyer in Houston
Head injury attorney in Houston
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 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 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.