Scholars may rightly claim the European Union's (EU) area of freedom, security and justice (AFSJ) has become one of the most significant developments in the European integration process. The Lisbon Treaty (LT) has the potential to push the AFSJ towards tremendous growth, and has provided the policy area with instruments that were unthinkable after the third pillar was created during the Maastricht Treaty negotiations. This article investigates the role of the European Commission in the process of constructing an ‘AFSJ’. It argues that the Commission (through alliances with other institutional actors) managed to incrementally contribute to this shift in political norms. This shift derived from the policy-making level from 1999 onwards. It manifested itself specifically during the negotiations of the Constitutional Treaty (CT) and the subsequent re-negotiation of the LT. Here, the Commission acted with the support and the use of other supranational actors during the Convention, without which this result would have been difficult, if not impossible, to obtain. Firstly, the article will deal with the main advances of the CT which resulted in the LT. Subsequently, the role of the Commission and other EU institutional actors will be examined, resulting in an overall evaluation.