Thiessen Law Firmbr 1221 Studewood St.br Houston, TX 77008br Call 713-864-9000br br DWI Lawyer Mark Thiessen doesn't charge for phone calls or text messages. When you hire us as your lawyer we're available 24 hours a day 7 days a week. We're a boutique law firm located in the Houston metro area. However we do take on clients the throughout the whole state of texas.