The principle of subsidiarity defined in the Treaty of the European Union and it is one of the main principles, which determines the areas of responsibility of the member states and the EU.

According to the principle of subsidiarity, in those areas that do not belong to the exclusive competence of the Union, it begins to act only if and only to the extent that the objectives of the intended action cannot be properly achieved by the Member States at the central, regional and local level, and at the Union level, due to the scale or impact of the intended action, it would be necessary to achieve them better.

It means that the principle of subsidiarity rules out the Union intervention when an issue can be dealt effectively by Member States at central, regional or local level. The Union is justified in exercising its powers when Member States are unable to achieve the objectives of a proposed action satisfactorily and added value can be provided if the action is carried out at Union level.

Since the Treaty of Lisbon entered into force, national Parliaments may within eight weeks submit a reasoned opinion on whether a draft legislative act of the EU complies with the principle of subsidiarity.

Control of the principle of subsidiarity is one of the key functions of the Seimas committees in the consideration of EU matters, which is carried out in accordance with the procedure established under the Statute of the Seimas.

If it is decided that the draft legislative act of the EU may not comply with the principle of subsidiarity, the conclusions by the Committee on European Affairs are forwarded for debate to the plenary sitting of the Seimas. It is then a subject to a special urgency procedure. The Committee on European Affairs is responsible for notifying the motivated opinion of the Seimas to other national Parliaments of the EU Member States and relevant EU institutions, as soon as possible.