An important principle of the treaties, stating that EU law-making should be as light as possible and not go beyond what is strictly necessary to achieve the objectives of the treaties. Also applies to EU supra-national lawmaking.
Attached to the Lisbon Treaty is a protocol on subsidiarity and proportionality. This allows 1/3 of national parliaments to react, within eight weeks, against a proposal for an EU-law. The Commission is then forced to review its proposal, but does not have to change it.
From September 2006, the Commission has sent proposals for new laws to control for subsidiarity and proportionality in the national parliaments.
See also Subsidiarity