The action for annulment is one of the main avenues to test the lawfulness of EU measures in light of EU fundamental rights. Through this procedure, the EU courts exercise their role of guardians of the Treaties by confirming or striking down EU measures. Accordingly, the action has both an ex post regulatory and a democratic control function, while ensuring the coherence of the EU legal order under a Kelsenian model of constitutional review. It is through procedure that EU fundamental rights exercise their influence in the action for annulment: both the parties to the litigation and the Court invoke procedural fundamental rights to delineate the process-based obligations imposed on EU institutions. In so doing, both the applicants and the EU courts shape fairness and the rule of law in the EU administrative space. The centrality of procedure in the judicial review of EU law is a direct reflection of the plethora of procedures that constellate the EU governance. Yet recent rule of law saga cases appear to signal a new direction towards more substantive pleas (and therefore contestation) of EU law.