• Born in 1957; education at Jean-Paul-Gymnasium (Hof an der Saale), Franz-Ludwig-Gymnasium (Bamberg) and Goethe-Gymnasium (Karlsruhe);
• 1976 prize of the Foundation F.V.S. (for paper on "La pensée française et l'héritage historique"); legal studies at the University of Heidelberg and the University of Cambridge (Clare College);
• 1981 first juridical state examination;
• 1983 Dr. jur. utr. (Heidelberg: summa cum laude); doctoral dissertation on the liability of the EEC for wrongful normative acts); clerkship at various judicial institutions (including the Federal Constitutional Court);
• 1985 second juridical state examination;
• 1985 research fellow at the Max Planck Institute for Comparative Public Law and International Law (Heidelberg); research areas: international arbitration, British and French law;
• 1989 Dr. jur. habil./venia legendi for German and foreign public law, public international law and European law (University of Heidelberg, law faculty; thesis on "The Liberty of Conscience and the Normativity of Positive Law" - Maier-Leibnitz-Prize: special prize for constitutional law awarded by the Federal Minister for Science);
• 1990 professor for public law at the University of Bonn;
• 1991 call to the University of Konstanz: chair for public international law and European law, constitutional and administrative law; 1993-94 vice-dean, law faculty;
• Since 1995 professor at the University of Bonn.
• 1999-2004 Vice-rector of the University of Bonn
• 2005 Corresponding Member, Academia de Jurisprudencia, Columbia
• 2006 Doctor juris honoris causa, University Colegio Mayor de Nuestra Senora del Rosario, Bogotá
• 2012 Member, Administrative Board of the Federal Academy for Security
• 2012/13 and 2013/14 Bonn Fellow at the “Käte Hamburger Kolleg”
• 2014-2015 Member, Commission of the Federal Parliament on the deployment of the armed forces
• 2014 Doctor juris honoris causa, University of Gran Colombia
• 2015 Doctor juris honoris causa, Pontifical Javeriana University
• 2016 Fellow at the Stellenbosch Institute for Advanced Study (STIAS)

Corresponding Member, Academy of Law of Colombia; Honorary professor at the Universidad Pontificia Javeriana (Bogotá); Honorary Professor of the Colegio Mayor de Nuestra Señora del Rosario, Bogotá; Visiting Professor, inter alia, at the University Paris I (Sorbonne), New York University (Global Law School); Universidad Autónoma de México, University of St. Gallen (HSG); Adjunct Professor at the City University of Hong Kong; Global Visiting Professor, SMU Law School, Dallas.

Member, Human Rights Committee of the International Law Association (ILA); Member, Advisory Council on Biodiversity and Genetic Resources of the Ministry of Agriculture; Member of the of the sixth advisory council of the Federal Academy for Security.

Advising legislative and executive bodies in Germany and other countries (constitutional law, international law, EU law)