Christophe Hillion is Professor of European Law at the universities of Leiden and Oslo, research professor at the Norwegian Institute of International studies (NUPI) and senior researcher at the Swedish Institute for European Policy Studies (SIEPS). He has published on external relations and constitutional law of the European Union. His present research focuses on the implications of Brexit for the European integration process, as well as on the protection of the rule of law and fundamental rights in the EU, and in its external action.