A founding partner of TSP, Dr. Theissen was admitted to the bar in 1990, the year in which he also earned his doctoral degree. Since 1998, he also has been active as an adjunct teaching faculty member for construction law as well as public procurement law at the Ber-liner Hochschule für Technik (BHT) – Berlin University of Applied Sciences). He obtained his license as a notary in 1999. From 2005 onwards, when he was admitted as specialist attorney, he has served as chairman of the Expert Committee for construction law as well as architect law of the Berlin Bar Association.
He has many years of experience in advising and representing governmental and private-sector clients all over Germany in matters involving construction law, architect / engineer law, public procurement law, and real estate law. He is co-editor of a commentary on the Honorarordnung für Architekten und Ingenieure (HOAI, Of-ficial Scale of Fees for Services by Architects and Engineers) as well as the author of numer-ous reference works, including a collection of template forms to be used in connection with the German Contracting Rules for the Award of Construction Contracts, Part B (VOB/B). Over the past fifteen years, he has been a regular participant and lecturer at seminars focus-ing on construction law, real estate law and public procurement law. He has full professional proficiency in German and English.