He is one of the most influential dogmatists of German penal law and has gained national and international reputation in this field.
Afterwards he worked as scientific assistant for professor Henkel where in 1957 he received a doctor's degree for his thesis Offene Tatbestände und Rechtspflichtmerkmale (open elements of a crime and attributes of statutory duty).
In 1966 he was one of the authors of the "Alternativentwurf für den Allgemeinen Teil des deutschen Strafgesetzbuchs" (alternative proposal for the general part of the German criminal law) which influenced German criminal law for years to come.
From 1968 to 1971 he also worked on the alternative proposal for the special part of the German criminal law which was released in four volumes.
In 1971, he became a professor at Ludwig Maximilian University of Munich where he lectured until 1999 and held the chair for penal law, criminal procedure and general legal doctrine.