Born October 23, 1937, in Wiesbaden, Heckelmann studied in Frankfurt, Marburg, and Mainz. He earned his doctorate in 1965 at the University of Münster, followed by Habilitation in 1972.

After initially working as a lecturer and research fellow, Heckelmann accepted an invitation to teach at Freie Universität Berlin in 1975. Visiting professorships abroad, in countries including the United States, Bolivia, Taiwan, Japan, Korea, and China, sparked his interest in and insight into the international aspects of law.

Heckelmann’s political involvement started early on, before he had even completed his degree, when he was a member of the academic self-administration in Mainz. At Freie Universität, he was a member of the Academic Senate, served as executive vice president for six years, and finally helped to shape the development of Freie Universität as its president from 1983 to 1991. From 1991 to 1996, Heckelmann served as the interior minister of the State of Berlin.

He passed away June 24, 2012, in Berlin.