The Doctrine of Union Preemption in the E.U. Internal Market: Between Sein and Sollen

The introduction by the Treaty of Lisbon of a catalogue of competencies into the TFEU eliminated the overlap between the preclusion of national lawmaking powers resulting from the exclusive character of E.U. competences and that attributable to the enactment of E.U. legislation. This opened the door for scholarly investigation of Union Preemption as a general theory of the effects of E. U. legislation in non-exclusive competence areas. The first aim of this work is to describe what the doctrine of Union Preemption is ("Sein") in the context of the E.U. internal market.