The principle of subsidiarity is not a mechanism for “returning powers’ to the member states, but for determining whether or not Community action should be set in motion.
The member states, through the EU treaties, set the EU certain tasks and give it the powers to achieve those tasks. Article 5 of the treaty establishing the European Community states that, in areas which do not fall within its exclusive competence, the Community shall take action, in accordance with the principle of subsidiarity, only if and in so far as the objectives of the proposed action cannot be sufficiently achieved by the member states and can therefore, by reason of the scale or effects of the proposed action, be better achieved by the Community.
Further guidelines for assessing whether these requirements are met are laid down by the Protocol on the application of the principles of subsidiarity and proportionality. The Protocol also requires the Commission to justify the relevance of any of its legislative proposals with regard to the principle of subsidiarity.
The Lisbon Treaty strengthens the role of national parliaments in EU decision-making, so that for the first time national parliaments could challenge draft EU legislation on subsidiarity grounds. It is for Parliament to decide how to exercise its rights under these procedures.
The Lisbon Treaty also, for the first time, empowered member states to withdraw from the European Union.