Keywords: Subsidiarity, National Parliaments, Treaty of Lisbon, Early Warning System, COSAC.
The article analyses the principle of subsidiarity in the light of the Lisbon Reform Treaty. It examines this new task for the national parliaments and the way it will be conducted. Despite being a relevant innovation, several difficulties in its implementation could emerge. In order to implement this reform, coordination and cooperation among national parliaments will be necessary. However, the legislative assemblies will have to work in an ampler setting together with the European Union's lawmakers. The development and outcome will not depend only on the national parliaments, but also on the dynamics within the EU institutional system. The scrutiny of subsidiarity by the national parliaments will involve several actors and probably there will be a positive outcome only if there is a constructive dialogue and inter-institutional cooperation.