On 18 December 2025, the Grand Chamber of the Court of Justice of the European Union (the Court) delivered its judgment in Case C-448/23, European Commission v Republic of Poland. In this momentous ruling, the Court held that Poland failed to fulfil its obligations under EU law as a result of two decisions adopted by the Polish constitutional tribunal (Trybunał Konstytucyjny) which openly and deliberately challenged core principles of the EU legal order such as, inter alia, the effectiveness of judicial protection and primacy of European Union (EU) law. The judgment constitutes one of the clearest judicial reaffirmations of the EU constitutional foundations to date and is particularly delicate in that the Court expressly took into account the systemic consequences of irregularities affecting the composition and functioning of the Polish constitutional tribunal. It also falls within the line of the Court’s case-law and, more widely, EU institutions’ initiatives aimed at countering the progressive erosion of the rule of law, judicial guarantees and civic space in Poland.
Background to the dispute
While its facts partly date back to the end of 2015, the case must be understood against the background of a broader series of disputes involving Poland and the European Union, relating to legislative reforms adopted by the Polish lower chamber (Sejm) between 2015 and 2023, during which it was dominated by the nationalist Law and Justice party (Prawo i Sprawiedliwość, PiS). Those reforms were repeatedly found by the Court to undermine judicial independence, weaken the separation of powers, restrict the civic space and limit the ability of national courts to apply and give effect to EU law. In that context, the Court was called upon to interpret and enforce EU law in relation to several legislative measures, including, inter alia:
- Legislation granting the President of the Republic discretionary power to extend the judicial activity of judges approaching retirement age, thereby allowing selective prolongation of mandates (Case C-619/18, judgment of 24 June 2019);
- Reforms of the disciplinary regime applicable to judges, including the establishment and operation of the disciplinary chamber of the supreme court (Sąd Najwyższy), under which judicial decisions applying EU law could be treated as disciplinary offences (Case C-791/19, judgment of 15 July 2021);
- Legislation prohibiting national courts from reviewing compliance with EU requirements concerning judicial independence and impartiality (Case C-204/21, judgment of 5 June 2023); and
- Measures restricting the review of the lawfulness of judicial appointments to constitutional courts and other judicial bodies (Case C-225/22, judgment of 4 September 2025).
In each of these cases, the Court found that the contested legislation infringed the requirements of judicial independence and impartiality, which constitute essential elements of the rule of law and are indispensable for ensuring effective judicial protection under EU law. The gravity and persistence of those breaches led the European Commission (the Commission), in 2017, to trigger the preventive mechanism under Article 7 of the Treaty of the European Union (TEU), a procedure later suspended following commitments by Poland to bring its legislation into line with EU requirements.
The dispute in the present case is rooted more specifically in the composition and functioning of the Polish constitutional tribunal. In November 2015, the newly elected PiS-dominated Sejm declared ineffective the appointment of several judges lawfully nominated by the preceding legislature, while the president of the republic declined to administer their oath of office. This enabled the appointment of replacement judges in January 2016. Those events were examined by the European Court of Human Rights, which, in its judgment of 7 May 2021 (Xero Flor v Poland), held that the appointment of one of the judges elected in 2016 had been affected by serious irregularities, impairing the very essence of the right to a tribunal established by law, as guaranteed by Article 6 of the European Convention on Human Rights, and undermining the rule of law.
Against that background, the Polish constitutional tribunal delivered two particularly controversial judgments in 2021. By its decision of 14 July 2021, it refused to recognise the binding nature of interim measures ordered by the Court under Article 279 of the Treaty on the Functioning of the European Union (TFEU), which required the suspension of the disciplinary chamber of the supreme court. The tribunal held that the Court had acted ultra vires, asserting that the Treaties did not confer competence to impose such measures on Polish constitutional bodies. The confrontation escalated further with the judgment of 7 October 2021, in which the Constitutional Tribunal extended its ultra vires reasoning to challenge, inter alia, the primacy of EU law over the Polish Constitution.
In response, the Commission initiated infringement proceedings under Article 258 TFEU. Meanwhile, a political change followed the 2023 parliamentary elections, won by the pro-European Civic Platform (Platforma Obywatelska, PO), resulting in Poland’s position being aligned with that of the Commission. Nevertheless, the Court considered it necessary to rule on the merits of the case, given the systemic constitutional challenge posed to the EU legal order and its potential impact beyond Poland.
The issues at stake
The issues raised by the case were of the highest constitutional significance. The legislative reforms adopted by the Sejm between 2015 and 2023 directly affected the organisation, independence and functioning of the judiciary, thereby striking at the core mechanisms through which EU law is applied and enforced at national level. Those reforms aimed, in particular, at reducing the autonomy of courts and exerting political control over the appointment and functioning of the Polish constitutional tribunal. In that context, the role of the President of the Republic did not operate as an institutional counterbalance. The refusal to administer the oath of office to judges lawfully appointed, combined with the acceptance of appointments subsequently made under contested procedures, formed part of the broader institutional crisis examined by both European and national courts.
The two judgments delivered by the Polish constitutional tribunal in 2021 further escalated that crisis by directly challenging the foundational principles of EU law. By asserting that the Court had acted ultra vires, the tribunal sought to deny the Court’s authority to interpret EU law and to order interim measures under Article 279 TFEU, a competence which the Court has exercised consistently since the early days of the European Communities. The tribunal substituted the autonomous interpretation of EU law with its own reading of the Treaties, treated as ordinary international agreements subject to constitutional override. On that basis, it held that EU law could not prevail over provisions of constitutional rank and claimed for itself, and for national authorities, the power to determine the limits of EU law primacy by reference to national constitutional identity.
While Article 4, para. 2, TEU requires the Union to respect the national identities of Member States, the interpretation advanced by the Polish constitutional tribunal went far beyond that provision. If upheld, it would have fundamentally undermined the principle of primacy, including in relation to constitutional norms, and deprived EU law of its uniform and effective application.
The consequences of such an approach would have been twofold. First, it would have required acceptance of a systemic weakening of effective judicial protection in Poland, in circumstances where the independence of the judiciary had already been compromised. In such a context, the capacity of national courts to apply EU law directly and to engage in judicial dialogue through preliminary references under Article 267 TFEU would have been seriously impaired. Second, the reasoning advanced by the tribunal would have produced a disruptive spill-over effect across the Union, preventing the Court from ensuring the uniform application of EU law and thereby calling into question the very coherence of the EU legal order.
Finally, the case also raised sensitive issues concerning the composition and functioning of the Polish constitutional tribunal itself. As recognised by the European Court of Human Rights in Xero Flor v Poland, serious irregularities affected the appointment of certain judges following the 2015 reforms, with the result that panels including such judges could not be regarded as tribunals established by law within the meaning of Article 6 ECHR. These findings reinforced the conclusion that the violations at issue extended beyond EU law, touching upon fundamental guarantees protected by the European Convention on Human Rights and the Polish constitutional framework itself.
The findings of the Court
In its 298-paragraph judgment, the Court held that the two judgments delivered by the Polish constitutional tribunal in 2021 infringed several fundamental principles of EU law. At the outset, the Court recalled that, although the Treaties were concluded in the form of international agreements, they constitute the constitutional charter of a legal order founded on the rule of law. Within that order, Article 19 TFEU entrusts the Court with the task of ensuring the interpretation and application of EU law. On that basis, the Court reaffirmed that national courts, including constitutional and supreme courts, cannot substitute their own interpretations of EU law for that of the Court without jeopardising its uniform application across the Union. By advancing an interpretation of EU law based on exclusively national constitutional criteria and by denying the Court’s jurisdiction to order interim measures under Article 279 TFEU, the Polish constitutional tribunal directly challenged the powers conferred on the Court by the Treaties.
The Court further emphasised that, upon accession to the European Union, Member States accept not only the binding force of the Treaties, but also the body of principles and case-law interpreting them, which together form part of the acquis communautaire. Unlike ordinary international agreements, EU law cannot be interpreted in isolation from the settled case-law of the Court. Accordingly, Poland could not rely on its constitutional law to claim that the Court’s interpretation of EU law exceeded the competences conferred by the Treaties. In that context, the Court restated its well-established case-law on effective judicial protection and the rule of law. While Member States remain free to organise their judicial systems in accordance with national constitutional traditions, EU law requires compliance with minimum standards necessary to guarantee judicial independence and impartiality. These include the requirement that courts be lawfully constituted, with judges appointed in accordance with procedures ensuring their independence.
Where those requirements are not met, the effectiveness of judicial protection is undermined, with systemic consequences for the enforcement of EU law. In particular, deficiencies affecting judicial independence may discourage national courts from applying EU law or from engaging in judicial dialogue through preliminary references under Article 267 TFEU. It was precisely to prevent such distortions that the Court ordered interim measures under Article 279 TFEU requiring the suspension of the disciplinary chamber of the Polish supreme court. The refusal by the Polish constitutional tribunal to recognise the binding nature of those measures was therefore found to constitute a serious threat to the effectiveness of judicial protection and to the rule of law.
Finally, the Court addressed the issue of the composition of the Polish constitutional tribunal. Drawing on the findings of the European Court of Human Rights in Xero Flor v Poland, the Court noted that serious irregularities had affected the appointment of certain judges following the 2015 reforms, in breach of Polish constitutional law. While the Court did not rule on the validity of the Tribunal as an institution as such, it acknowledged that the participation of judges appointed under such irregular procedures could undermine the requirements of a tribunal established by law and, consequently, the guarantees of effective judicial protection under EU law.
The way forward
The judgment is of paramount importance, as it enabled the Court not only to restate core principles of EU law, including the effectiveness of judicial protection, the primacy and uniform application of EU law, but also to clarify the scope of Article 4, para. 2, TEU. The requirement to respect the national identities of Member States cannot be interpreted in a manner that allows unilateral, constitutionally framed readings of EU law disregarding the Court’s settled case-law. On the contrary, by acceding to the Union, Member States accepted not only the Treaties themselves, but also the system of values, principles and judicial interpretations through which those Treaties are given effect. Within that framework, the Court remains the principal guarantor of the balance between EU law and national constitutional identity.
Member States are not deprived of legal means to contest the validity or interpretation of EU acts. The Treaties provide a structured set of remedies, including actions for annulment under Article 263 TFEU, as well as the preliminary ruling mechanism under Article 267 TFEU, which allows national courts and individuals to raise questions of validity or interpretation before the Court. What EU law does not permit, however, is a unilateral redefinition of the limits of EU competences by reference to purely national constitutional criteria, nor the characterisation of the Court’s exercise of its Treaty-based powers as ultra vires.
This point is particularly significant in light of recent tensions affecting the dialogue between the Court and national constitutional courts, a dialogue which has historically played a central role in the integration of EU law within domestic legal orders. While that dialogue has occasionally encountered friction, including in the judgment of the German Bundesverfassungsgericht of 5 May 2020 concerning the European Central Bank’s Public Sector Purchase Programme, such tensions have traditionally remained within a framework of mutual recognition of jurisdiction and ultimate compliance with EU law.
However, the present case differs in nature and intensity, as it forms part of a broader pattern of judgments and legislative reforms reflecting a sustained deterioration of the rule of law in Poland, a development which the Court has repeatedly been called upon to address. At the time of writing, issues relating to the composition and functioning of the Polish constitutional tribunal remain unresolved, while legislative efforts to reverse earlier reforms continue to face political obstacles.
As a result, the judgment, while constitutionally decisive, does not in itself resolve the underlying institutional stalemate. EU citizens and economic operators in Poland remain exposed to a weakened system of judicial protection and the risk cannot be excluded that similar challenges to the authority of EU law may arise elsewhere, notwithstanding their fragile legal foundations. In that context, the judgment stands both as a reaffirmation of the constitutional integrity of the EU legal order and as a reminder that the effectiveness of that order ultimately depends on the continued commitment of Member States to the rule of law.
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