Professor at the University of Cologne, Chair of Civil Law, Commercial and Corporate Law, Labour Law and European Private Law Development.

Judge and since 1 June 2021 President of the North Rhine-Westphalian Constitutional Court.

1986-1990 Head of the legal department of a listed family-owned stock corporation; 1988-1994 Lecturer in civil law and corporate law at the Wissenschaftliche Hochschule für Unternehmensführung in Koblenz; 1991-1994 Lecturer in commercial and corporate law at the DSGV Bonn; 1997 Habilitation in Mainz; 1998 Professor of Civil Law, Commercial and Corporate Law, Labour Law and Civil Procedure Law in Hagen/Düsseldorf; Vice-Rector for Teaching, Studies and Academic Reform/Hagen, Vice-Rector for International and Public Relations/University of Cologne. Since 2006 visiting professor at Université Paris 1/Panthéon-Sorbonne for labour and commercial law. Since 2015 Chairwoman of the Foundation Board and Deputy Chairwoman of the Supervisory Board of EBS University of Business and Law. 1 June 2017: Honorary doctorate from EBS Law School. March 2018 to February 2023: Member of the University Council of the University of Vienna 25 February 2021: Federal Cross of Merit First Class.

Numerous publications in civil law, commercial and corporate law and labour law; numerous publications on the German reform of the law of obligations (Schuldrechtsreform).