The Costanzo Obligation

National administrative authorities are obliged to leave provisions of national law unapplied when these are incompatible with EU law. Irrespective of their position and powers under national law, national administrative authorities are supposed to comply with this so-called ‘Costanzo obligation’ as established by the Court of Justice. This raises questions of both European Union law and national constitutional law, particularly with regard to the principle of legality. This book explores three issues. Which European obligations apply to national administrative authorities with regard to provisions of national law that are incompatible with directly effective provisions of European law? Which national constitutional obstacles do they come across by giving effect to these obligations? And how should the tensions between the European obligations and the national constitutional obstacles be solved? The national law part of the research is focused on the legal systems of France, Germany and the Netherlands. The last question combines the European and national perspective and reveals a clash, which gives rise to the question whether the obligation in the current form should be maintained.

The ‘Costanzo obligation’ has not been explored very often thus far, as the focus is mostly on the application of EU law by national courts. This research shifts the focus to the position of national administrative authorities in cases of conflict between national law and European Union law. Moreover, the book offers a new point of view as it not only discusses the European perspective, but also explores the ‘Costanzo obligation’ from the viewpoint of the Member States in a comparative legal study. This combined approach makes the book interesting and valuable for readers with a background in European law or in national constitutional and administrative law.


About the book
‘[A] PhD which is worth reading. The research is thorough and the approach is very original. The results give food for thought for both scholars and policy-makers at the national and European level.’
Flora Goudappel in (2012) 37 E.L. Rev.

‘[V]erhoeven’s work is a valuable academic publication, written in a clear and user-friendly way, at the same time using lucid and coherent argumentation. It contains clearly presented theses which are reflected in the conclusions, combined with interesting de lege ferenda titles. Also particularly valuable is the legal comparative research which shows the position of administrative authorities in national constitutional orders. The reviewed monograph is thus an interesting publication which may by all means be recommended to readers interested in issues involving the application of EU law in national legal orders.’
Maciej Taborowski in 2012 CMLR 1502.