He joined the European Commission in 1978, becoming Director for Competition Policy at the Directorate-General for Competition in 1995, Deputy Director-General in 1999 and Spokesman and Director-General of Press and Communication in 1999. He was Director-General of Justice and Home Affairs (later Justice, Freedom and Security) from 2003 to 2010.
He was Director-General of Internal Market and Services Directorate-General from 2010 to 2015. In the first half - Director-General for the Directorate-General for Financial Stability, Financial Services and Capital Markets Union which was formed from the DG Internal Market and Services Directorate-General.
On 24 June 2015, the European Commission announced that he would become the Director-General of a to-be-created "Task Force for Strategic Issues related to the UK Referendum" as of 1 September 2015.
He studied law at the University of Sussex and has an MA from the College of Europe in Bruges. He has been a visiting lecturer at Sciences Po, a visiting fellow of the University of Cambridge Centre for European Legal Studies, a visiting professor at the College of Europe since 2009 and Professor of Law at the Free University of Brussels since 1989.