This document is an excerpt from the EUR-Lex website
The principle of subsidiarity is defined in Article 5(3) of the Treaty on European Union. It aims to ensure that decisions are taken at the closest possible level to the citizen and that constant checks are made to verify that action at the European Union (EU) level is justified in light of the possibilities available at the national, regional or local level.
Specifically, it is the principle whereby the EU does not take action (except in the areas that fall within its exclusive jurisdiction), unless it is more effective than action taken at the national, regional or local level.
It is closely linked to the principle of proportionality, which requires that any action taken by the EU not go beyond what is necessary to achieve the aims of the treaties. Another related principle, the principle of conferral, states that any policy areas not explicitly agreed in the treaties by all EU Member States remain in their domain.
There are two relevant protocols annexed to the Treaty of Lisbon:
In the event of a breach of the principle of subsidiarity, the European Committee of the Regions or Member States may refer an adopted act directly to the Court of Justice of the European Union.