Subsidiarity Ex Ante and Ex Post: From the Early Warning System to the Court of Justice of the European Union

The subsidiarity principle divides competences between the European Union and its Member States. The Lisbon Treaty suggests a connection between ex ante and ex post subsidiarity review. Ex ante, national parliaments were given a role via the early warning system (EWS). Ex post, legislation is subject to review by the Court of Justice of the European Union (CJEU). More than 10 years after Lisbon, this article is the first to theorize and evaluate whether there is indeed a connection. Our theory predicts a conditional connection. Quantitatively, we provide a two-way classification of Member States based on their use of the EWS and CJEU subsidiarity cases. Qualitatively, we look back from court cases to the Council stage and analyse the Advocate General's opinions in subsidiarity cases. We find a weak conditional connection. A key explanation appears to be the Court's limited willingness to enforce subsidiarity and hence the limited incentives to go to court.

Automated summary

The subsidiarity principle in the European Union is connected to both ex ante and ex post subsidiarity review, involving national parliaments through the early warning system (EWS) and the Court of Justice of the European Union (CJEU) reviewing legislation. This article theorizes and evaluates the existence of a connection between the two, finding a weak conditional connection. Limited enforcement of subsidiarity by the Court appears to be a key explanation.