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

Website: thetexastrialattorney.com

Board Certified National Task Force Task-Force-Member 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 *

Submit Form

Find an Attorney

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.

FIND AN ATTORNEYSearch

Members in the SpotlightMembers in
the Spotlight
06/27/2025

Priscilla Frisby

Priscilla Frisby: The NCDD Member in the Spotlight is Priscilla Frisby of Tucson, Arizona. Priscilla has practiced law for approximately 17 years. She speaks fluent Spanish. Priscilla was born in Douglas, Arizona and raised in neighboring Agua Prieta, Sonora, Mexico (across the border from Douglas, Arizona). At the age of 10, her parents bought a house on the United States side,...

Read More
View All

Members in the SpotlightLatest from
Our Blog
09/02/2025

Oral Fluid Testing: Roadside vs. Evidential Analyses

Written by Ashley M. Hart As cannabis is being decriminalized in many states, there has been increased interest in rapid roadside tests to detect THC and other substances for intoxicated driving charges. A...

Read More
View All

FROM OUR BLOG

Oral Fluid Testing: Roadside vs. Evidential Analyses

09/02/2025

Written by Ashley M. Hart As cannabis is being decriminalized in many states, there has been increased interest in rapid roadside tests to detect THC and other substances for intoxicated driving charges. A majority of states now have oral fluid testing in some form: roadside (presumptive) or evidential (confirmed in a lab). These states include Alabama, Alaska, Arkansas, Arizona, California, Connecticut,...

Read More

Interview With an Amicus

06/27/2025

Written by Michelle L. Behan Amicus Curiae (Latin for "Friend of the Court") refers to a brief that is filed by an interested, non-party to the matter under consideration. This is often done in cases where organizations and entities wish to provide the reviewing court with their point of view, be it social or public policy implications, or special interest agendas....

Read More
Read All Posts
Back to Top