Despite the shock provoked by the Snowden revelations, mass surveillance is still a reality in the EU. However, over the past few years, it has been possible to observe a gradual constitutionalization of these practices. This Article maps the ongoing process of progressively defining the constitutional limits and societal affordances of mass surveillance in the EU by focusing on the three main actors who contribute to it. First, this Article presents civil society as the propeller of this trend. Civil society not only advocated for a ban on general surveillance systems in the aftermath of the Snowden revelations, but also promoted a series of strategic litigations to challenge state surveillance practices at national and EU levels. Second, it analyses CJEU case law as the main constitutionalizing engine of this process. The Court pragmatically ascertained that an absolute prohibition of mass surveillance did not appear to be a realistic solution and put significant effort into actively defining the legal boundaries of these practices by striving to find an equilibrium between Member State interests and citizens' fundamental rights. Third, it considers the approaches taken by national legislators to be a slowing factor. States are still reluctant to incorporate the constitutional standards progressively developed by courts despite the now significant body of judicially created parameters in the field.
