Open data allows new experiments in administration, both in terms of activities and organisation. In terms of composite procedures, open data can serve many public interests in new ways, leading to faster and more accurate decision-making (already at the preparatory level), while it remains difficult to ensure effective judicial protection for individuals in shared administration between the EU and the Member States. In this context, procedural guarantees at the decision-making stage should not be neglected, even more if we consider the EU public administration as a platform, offering data as services, exchanging information and data, cooperating, and competing with public and private actors. Relying on the power of data, however, requires resilient rules, based on EU principles as to assure the rule of law, and able to cope with the challenges of the digital transition, as to ensure the “effectiveness” of administrative activities implementing EU law in each Member State.