The democratic deficit in the European Union proposes a series of questions about democratic legitimacy in decision-making processes at the community level. Although there are different factors involved which configure this democratic deficit, this study only focuses on the analysis of two aspects: on the one hand, the institutional weakness of the European Parliament against the Council predominance in the process of legis- lative approval in the EU, and, on the other, the opacity of this legislative process, which hinders the correct information of EU citizens and also prevents the implementation of accountability mechanisms. To address these questions, the Lisbon Treaty makes a number of reforms and new additions that seek both to strengthen the European Parliament into the legislative process