Professor Dr. Ziegert has been active in the field of commercial criminal law (Wirtschaftsstrafrecht) for over 30 years. Commercial criminal law (also known as business crime or white-collar crime) covers a wide range of crime, including classic offenses such as fraud, money laundering, and breach of trust, in addition to offenses in regulated areas such as the German Patent Act, Copyright Act, and Unfair Competition Act.

Prof. Ziegert has been active in appeal proceedings before the German Federal Court of Justice (Bundesgerichtshof, BGH) for more than 30 years. Until 2020, he was a lecturer at the German Lawyer Academy (Deutsche Anwalt Akademie) in Berlin, where he trained criminal law specialists. He is an honorary professor at the Ludwig-Maximilians-Universität in Munich, where he teaches criminal law and criminal procedure.