The Żurek ruling constitutes a significant development in the ECJ’s rapidly growing body of case law on the rule of law. It addresses the complex issue of what status ought to be ascribed to rulings issued by persons whose judicial appointments are considered irregular. This issue, for a long time pertaining to marginal cases in democratic States, has great practical significance, especially in Poland. There, the quality of an independent and impartial tribunal established by law has been questioned in the case of persons who obtained judicial appointments on the recommendation of the National Council of the Judiciary (NCJ) following a change in its composition in 2018. Such nominees, whose number at the time of writing amounts to 1788, have delivered thousands of rulings. Therefore, deciding on the status of their decisions raises important issues of the rule of law, res judicata, and legal certainty. The ECJ’s decision in the commented judgment could be read as developing the principle of primacy to a point where it requires, in certain situations, to consider rulings issued by persons irregularly appointed to judicial office as legally non-existent by virtue of EU law.