This principle has always underpinned the European Union, but it was explicitly specified for the first time in the failed Treaty establishing a Constitution for Europe and carried over into its replacement, the Treaty on the Functioning of the European Union. 2) After the treaty of constitutional treaty was rejected in France and Holland in 2005 because the union was taken too much power than it meant to be, and also lacks accountability, transparency and clear cut division of competences in the union, this was carried over in to the treaty of Lisbon.
Art 4 and 5 TEU provides the principles of competence, fidelity, conferral, subsidiarity and proportionality. And Art 2-6 TFEU provide further details about the categories and areas of union competence and the division of competences.
Art 5(1) TEU provides that the limit of union competences are governed by the principle of conferral, and that the use of union competences are governed by the principle of subsidiarity under Art 5(3) and proportionality under Art 5(2) which are both concerned with the exercise of powers and rely on protocol 2 for definition, and the union acts are open to possible challenges if breached proportionality.
Art 3 TFEU sets out the exclusive competences for example, e.g. customs duties, in which member states cannot act at all, Art 4TFEU sets out the areas of shared and concurrent competences, whereby the member states may act if the EU has not yet aced or