Olivier Costa is Director of European Political and Governance Studies at the College of Europe, Belgium, and Research Professor in Political Science and EU studies at the Centre National de la Recherche Scientifique, CEVIPOF-Sciences Po, France. He is also Executive Editor of the Journal of European Integration. Steven Van Hecke is Assistant Professor in Comparative and EU Politics at the Public Governance Institute of the KU Leuven, Belgium, and Senior Research Fellow at the Leibniz-Institut für Europäische Geschichte in Mainz, Germany.