In addition, he was appointed as fellow at the Center for the Study of Law, Administration, and Society (CRBS). A graduate of the Freie Universität Berlin, he obtained a doctorate in law from the University of Groningen in the Netherlands, and he is a fully qualified lawyer in Germany. A commercial edition of his comparative study on the democratic accountability of the European Central Bank has been published by Hart Publishing, Oxford. He publishes frequently on issues relating to central bank governance and economic and monetary union, as well as on other aspects of European law, including a major textbook on European Union law.