Abstract The Treaty of Lisbon has introduced a complex new typology of acts, distinguishing between legislative, delegated and implementing acts. This reform, the first since the Treaty of Rome, will have an impact on some of the most contested topics of EU law, touching several central questions of a constitutional nature. This article critically analyses which potential effects and consequences the reform will have. It looks, inter alia, at the aspects of the shifting relation between EU institutions, the distribution of powers between the EU and its Member States, as well as the future of rule-making and implementation structures such as comitology and agencies.