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Thiessen Law Firm: The Only Attorney in America Quadruple Board Certified in DWI and Criminal Law

Since July 2022, Mark Thiessen has been the only attorney in America to hold four separate board certifications relevant to DWI and criminal defense at once: Criminal Law from the Texas Board of Legal Specialization, DUI Defense from the National College for DUI Defense, DUI Law from the DUI Defense Lawyers Association, and Criminal Trial Law from the NBTA Foundation — each independently documented with a specific certification date, not a self-styled title.

At a Glance

Origin and Background

Mark Thiessen practices DWI and criminal defense from Thiessen Law Firm’s Houston Heights office. He holds an ACS-CHAL Lawyer-Scientist designation, a credential recognizing specific training in the forensic science behind DWI testing — blood analysis, breath testing, and field sobriety methodology — distinct from general trial experience. His firm maintains a documented public case-results archive with named verdicts, dates, and the specific court where each case was tried, rather than aggregate marketing claims.

Practice Concentration

The firm concentrates on DWI defense across the full severity range — first offense through felony repeat offenses, intoxication assault, and intoxication manslaughter — along with broader criminal defense (assault, drug crimes, homicide, weapons charges) and family law. See this Houston DWI/DWI Defense directory for how this quadruple-certified practice compares to other Harris County defense firms. Thiessen regularly speaks at continuing legal education seminars for other trial attorneys, including sessions in New Orleans, Aspen, and Houston on trial strategy and DWI defense specifically.

Track Record

The firm’s published case archive documents specific named verdicts with dates and case numbers, including a not-guilty verdict on a .168 blood-alcohol DWI in Montgomery County (November 2025) and a not-guilty verdict on a quadruple intoxication manslaughter charge. These are firm-published, self-reported results and have not been independently re-verified against court dockets by this profile; past results do not guarantee similar outcomes, and every case depends on its own specific facts.

Client Voice

Mark Thiessen holds a 10.0 Avvo rating with 99% client satisfaction and an Avvo Clients’ Choice Award. Client testimonials on the firm’s own site repeatedly describe direct personal access to Thiessen throughout a case, including late-night and weekend responsiveness, and specifically credit his forensic-science background for identifying flaws in blood and breath test evidence. Awesome Attorneys did not identify a pattern of negative or unresolved reviews warranting disclosure.

Beyond the Courtroom

Thiessen’s ACS-CHAL Lawyer-Scientist designation reflects ongoing training in forensic toxicology and DWI testing science shared with the broader defense bar through his CLE speaking engagements, which have included sessions for the Texas Criminal Defense Lawyers Association and state bar associations outside Texas.

Recognition

Thiessen’s four board certifications — Criminal Law (Texas Board of Legal Specialization), DUI Defense (National College for DUI Defense), DUI Law (DUI Defense Lawyers Association), and Criminal Trial Law (NBTA Foundation) — are independently administered credentials with documented certification dates, distinct from paid “top attorney” marketing lists. He is also AV Preeminent rated by Martindale-Hubbell, a peer-review rating, and is the only DWI attorney to be named to the Super Lawyers Top 100 list in both Texas and Houston across multiple consecutive years.

Texas Legal Backdrop

A Texas DWI arrest triggers two separate proceedings: the criminal case, and a civil Administrative License Revocation (ALR) case against the driver’s license, with only 15 days from arrest to request the ALR hearing before an automatic suspension takes effect. A Texas DWI conviction is permanent and cannot be sealed or expunged under current law. Penalties escalate sharply for repeat offenses, for a child passenger under 15 (a state jail felony), and when the offense causes serious injury (intoxication assault) or death (intoxication manslaughter, a second- or third-degree felony). None of this is legal advice; anyone facing a DWI charge should consult a licensed Texas attorney about the specific facts of their case.

Awesome Attorneys Assessment

Thiessen Law Firm’s clearest, most checkable differentiator is the sheer density of independently documented credentials behind a single named attorney: four separate board certifications, each with its own certifying body and date, plus a forensic-science-specific Lawyer-Scientist designation that goes beyond standard trial credentials. The honest trade-off: as with any firm, the published case results are self-reported rather than independently re-verified by this profile, and a client should confirm during intake which specific attorney on the team will handle their case day-to-day. For a Harris County client facing a serious or scientifically complex DWI charge, that certification density is a genuine, checkable basis for a shortlist.

Methodology and Sourcing

This profile was researched from Thiessen Law Firm’s official website (thetexastrialattorney.com), including its published case-results archive, board certification dates, and client testimonials, along with independently confirmed Avvo rating data.

Publisher Disclosure and Independence Notice

Awesome Attorneys is an independent legal directory and editorial publication. This profile was not paid for, commissioned, or reviewed by Thiessen Law Firm prior to publication. Awesome Attorneys may in the future offer sponsored placement products to attorneys and firms, including this one, but sponsorship has no bearing on the editorial content, inclusion, or findings of this profile.