Born 1956 in Cologne. Study of law, doctorate Tübingen Univ. (1988), German Habilitation Hamburg Univ. (1992), Full Professor Osnabrück Univ. (1992), head of the Project Group "Law of Common Goods" of the Max Planck Society (1997), Director and Scientific Member of the Max Planck Institute for Research on Collective Goods (since 2003), Professor Univ. Bonn (2003), Honorary Professor Univ. Osnabrück (2004).