The Treaty of Lisbon has introduced several modifications concerning the EU courts that have already had a significant impact on their activity. The most important one is the possibility for all national courts to address to the Court of Justice references for a preliminary ruling on the interpretation and validity of acts of the Area of freedom, security and justice. A similar impact can be attributed to the possibility for natural and legal persons to contest regulatory acts which are of direct concern to them. However, the Treaty of Lisbon has also introduced modifications that have not had any significant impact on the activity of the EU courts. This is the case, for example, for the provisions on actions brought by national Parliaments for infringement of the principle of subsudiarity or the provisions on direct actions in the Area of freedom, security and justice.