Follow the leader: the European Commission, the European Court of Justice, and the EU's rule of law revolution

The autocratization of Hungary and Poland prompted a revolution in the European Court of Justice (ECJ)'s caselaw. Brick by brick, the ECJ imposed novel obligations on EU member states to safeguard the rule of law while expanding the legal bases for the EU to sanction governments breaching the Union's fundamental values. In this article, we ask whether the ECJ pioneered this rule of law revolution or, conversely, whether the Court responded to an entrepreneurial European Commission acting as 'guardian of the Treaties'. While supranationalist theories depict the Commission as a proactive agenda-setter guiding the Court's innovations, studies of the EU's rule of law crisis argue that the Commission dragged its feet or only recently seized the reins of leadership. Which perspective is closer to the mark? Deploying a new theoretical framework to study judicial innovation and agenda-setting on an original dataset of all rule of law cases adjudicated by the ECJ from 2010 through 2023, we demonstrate that the Commission has been an inconsistent and often indifferent agenda-setter. Besides several proactive interventions limited to the latter years of the Juncker Commission, the Court's innovative rulings prompted the Commission to act more than the reverse, belying a fundamental shift in leadership.