Birke Häcker is Schlegel Professor of Civil Law, Common Law and Comparative Law, and Director of the Institute of International and Comparative Private Law, University of Bonn, Germany. Johannes Ungerer is Erich Brost Senior Research Lecturer in German Law, European and International Private Law at the Law Faculty and St Hilda’s College, University of Oxford, UK, as well as Global Associate Professor of Law, University of Notre Dame (USA) in England.