Born in Berlin on 15 November 1964. Studied law, Spanish and modern Greek in Würzburg, Lausanne, Freiburg i.Br. (1984-1990). First and Second State Examination (1990 and 1993). Legal traineeship (Referendariat), incl. international legal work at the German embassy in Quito, Ecuador and at the Max-Planck-Institute of Foreign and International Criminal Law, Freiburg, Germany (1990-1993). Teaching and research assistant in public international law and European law, Albert-Ludwigs-University of Freiburg (1990-1994) and doctorate in law (1994). Master of Laws (LL.M.), Harvard Law School (1994-1995). Wissenschaftliche Assistentin at the Walther-Schücking-Institute of Public International Law (1995-2001) and Habilitation, Christian-Albrechts-University Kiel (2000). Professor, chair of public international law and constitutional law, University of Basel, Switzerland (2001-2013). Dean (2004/05) and dean of research (2008-2013) of the Basel Law Faculty. Since 2013 Director and Scientific Member at the Max Planck Institute for Comparative Public Law and International Law.
Member of the Swiss National Research Council (2008-2013). President of the European Society of International Law (2010-2012). Member (substitute) of the European Commission for Democracy through Law (Venice Commission) in respect of Germany (2011-2015). Professor at the University of Basel (since 2013), the University of Heidelberg (since 2014) and at the Free University Berlin (since 2015). Visiting professor at Sciences Po, Paris (2009), the Université Panthéon-Assas, Paris (2014), the Peking University Institute for International Law (2014) and the Université Panthéon-Sorbonne, École de droit, Paris (2015).