Mark R. Thiessen

Mark R. Thiessen

Fighting for the People and Winning.

733 E. 12th 1/2 Street
Houston, TX 77008

Phone: 713-864-9000


Board Certified General Member

About Mark R. 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 (1) Criminal Law by the Texas Board of Legal Specialization 2018; (2) DUI Law by the DUI Defense Lawyers Association 2018; and (3) DUI Defense Law by the National College for DUI Defense through the American Bar Association 2020. 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), 2020-21 President of Harris County Criminal Lawyers Association (HCCLA) and a Charter Member and Parlimentarian for DUI Defense Lawyers Association (DUIDLA). Mark is a 9 time Texas Super Lawyer and in the Top 100 Super Lawyers in Houston (2017-21). From 2019-21, Mark was the only DWI lawyer to be named to the Top 100 Super Lawyers in all of Texas. Mark has won DWI trials from total refusals up to quadruple intoxication manslaughter.

Contact Mark R. Thiessen

Provide some details about your situation, but remember not to include sensitive information. An attorney-client relationship is only formed once an attorney formally agrees to represent you.

Your Name *

Phone Number

Email Address

Message *


Enter your city, state, or Zip code below to locate a qualified attorney who has demonstrated a commitment to defend those accused of DUI and related crimes.



Necessity of Diversity, Equity, and Inclusion in Criminal Defense Practice


By Steven Hernandez The practice of criminal defense law, like any other facet of society, thrives on the principles of diversity, equity, and inclusion (DEI). These principles are not just ethical necessities in our increasingly multicultural societies, they are also pivotal for the delivery of justice in the criminal defense landscape. Diversity in criminal defense law practice refers to the recognition and...

Challenging Breath Test Results


By Eric H. Sills, Esq. There are a number of challenges that can be made to the validity of a breath test result. Some of the more common are set forth below. Keep in mind that the author is from New York, which is both (a) a "one-blow" State, and (b) a blood alcohol concentration ("BAC") State, not a breath alcohol...

Back to Top