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Mark Thiessen

Aspen DUI, Criminal, & Personal Injury Attorney

Mark Thiessen 

DUI, Criminal, & Personal Injury Attorney in Aspen

Mark Thiessen is an aggressive trial attorney who offers quality representation in Aspen for DUI Defense, Criminal Defense, and Personal Injury cases. Though he is renowned for being an aggressive, trial-tested lawyer, clients flock to Mark for his likable and honest personality. He passionately represents Pitkin County, CO residents at trial or during negotiation processes to achieve the most favorable outcome for his clients. 

For a free consultation, contact Thiessen Law Firm today at 970-233-9000! 


Since founding Thiessen Law Firm in 2011, Mark’s list of accomplishments have continued to grow. He has earned the honor of Super Lawyer from the years 2013-2021, becoming the youngest criminal Super Lawyer in Texas in 2013. He is Board-Certified in both DUI Defense by the National College for DUI Defense (as approved through the American Bar Association) and DUI Law by the DUI Defense Lawyers Association. In addition, Mark has also 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. 

In addition to DUI defense, Mark has also expanded his firm’s leadership into additional practice areas, including:

  • DWAI
  • Felony DUI
  • DUID
  • Vehicular Homicide
  • Vehicular Assault
  • Skiing Accidents
  • And more… 

Over the years, Mark’s expertise has put him in high demand. Amongst his many speaking engagements, Mark is a frequent legal seminar lecturer and has published numerous legal articles that have only furthered his positive reputation with members of multiple communities nationally and internationally. He has had the pleasure to educate students, fellow attorneys, law enforcement members, and judges. 

In addition, Mark serves as a faculty member for multiple legal organizations including holding the position of Charter Member, Treasurer, and Director for the DUI Defense Lawyers Association (DUIDLA). 

Background & Education

Born and raised in Houston, Texas, Mark graduated from Texas Christian University in 2000 with a Bachelor’s of Business Administration in Marketing. Shortly after, he began his law career by studying at the South Texas College of Law (STCL) where he participated in mock trials and campus law societies. However, his passion for the law did not keep him solely in Houston: he studied abroad at the International Criminal Law at the University of Malta, the BPP Law School in London, England, and at the University of Hawaii to gain a more well-rounded perspective and understanding of different cultures –– something you can see in his personality right away. 

After gaining experience in the working legal field, Mark decided to open his own firm, Thiessen Law Firm, in 2011. Though he is a well-known, board-certified DUI attorney, Mark is well-versed in constitutional law and multiple areas of science including anatomy, physiology, toxicology, chemistry, computer science, biology, and physics. This knowledge gives him a strategic advantage in the courtroom over his competitors. Mark has earned a formidable reputation amongst his clients and legal peers. He is someone who is obsessed with winning but values his relationships with his clients above all. He is a licensed attorney who tries cases in both Texas and Colorado.

Since 1985, Mark and his family have split their time between both Texas and Colorado. After spending over 35 years in Colorado, the Thiessen’s have made a home in the beautiful state –– including Mark’s father who has retired from medicine and currently lives in Silverthorne. 

In his free time, he competes in Brazilian jiu-jitsu as a black belt for Brazil-021 Houston School of Jiu Jitsu and also trains Muay Thai. He is an avid Colorado snow skier who loves spending time with his wife, Taly, and two children. But his main passions lie in finding justice for his clients.

If you need a win, you need an attorney who does not back down. You can count on Mark Thiessen to fight for your rights. Contact Mark Thiessen today by calling 970-233-9000.


DUI Defense Lawyers Association Board Certified
National College for DUI Defense Board Certified
ACS-CHAL Lawyer Scientist
Colorado Bar Association
Boulder Bar Association
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aggressive defense