The EU competence regarding the principle of subsidiarity refers to actions taken only in case that certain goals can be achieved more effectively than member states can achieve them by actions taken at national, regional or local level. The action taken is proportional i.e." it should not go beyond what is necessary to achieve the objectives of the Treaties''. If the Union legislator, the Parliament and/or the Council receive a legislative proposal from the European Commission before the first reading or in legislative phase, it deems whether this proposal is in compliance with the principle of subsidiarity whereas legislative decisions are passed on to national parliaments for approval regarding the assessment of the respect for the principle of subsidiarity. The interesting role has been give the Committee of the Regions whose powers have been extended according to the Treaty of Lisbon, thus it can defend regional interests according to the principle of subsidiarity by instituting proceedings before the Court of Justice of the European Union. Regarding the impact of this principle, case law has been too scarce as to have and send an expected message and thus legislator's monitoring becomes significant taking into consideration opinions on compliance of EU legislative acts regarding subsidiarity; these opinions are made by the Committee of the Regions and national parliaments.