What is subsidiarity
​​Subsidiarity is a principle guiding the sharing of competences for policy and law-making between the European, national and sub-national (regional and local authorities) levels.  
 
The principle of subsidiarity is defined in Article 5 of the Treaty on European Union. It is intended to ensure that decisions are taken as closely as possible to the citizen and that constant checks are made as to whether action at Community level is justified in the light of the possibilities available at national, regional or local level.  
 
Specifically, it is the principle whereby the Union does not take action (except in the areas which fall within its exclusive competence) unless it is more effective than action taken at national, regional or local level.  
 
It is closely bound up with the principle of proportionality , which requires that any action by the Union should not go beyond what is necessary to achieve the objectives of the Treaty.