The principle that the content and form of European Union action shall not exceed what is necessary to achieve the objectives of the Treaties.

The principle of proportionality is one of the general principles of EU law. Together with the principle of subsidiarity, the principle of proportionality regulates the exercise of the powers conferred by the member states to the EU (see Practice note, EU law essentials: Scope of EU powers and competences).

The principle of proportionality is laid down in Article 5 of the Treaty on European Union (TEU). EU institutions and bodies must apply it in accordance with the criteria set out in Protocol (No 2) on the application of the principles of subsidiarity and proportionality annexed to the Treaties.