National constitutional identity and ultra vires action: checks on its use against the legal order of the European Union Commentary on Judgment C-448/23 of the Court of Justice of the European Union of 18 December 2025

Abstract

The Court of Justice, sitting as the Grand Chamber, has ruled on an action for infringement filed by the European Commission against the Republic of Poland in relation to two judgments of its Constitutional Court which declared several provisions and principles conforming to the legal order of the European Union to be incompatible with the Constitution.

Furthermore, the contested judgments were issued by a court formed following a dispute over the appointment of its judges between two opposing parliamentary majorities at the start of the new parliamentary term; they are a continuation and consequence of the reforms implemented in the Polish judicial system, to which the Court of Justice has been reacting in order to safeguard the requirements of EU law within the framework of the rule of law.

The Court of Justice responds by reaffirming the need to ensure effective judicial protection by independent and impartial courts, and by rejecting Member States’ attempts to invoke national constitutional identity or ultra vires actions to justify the adoption of measures against EU law.