Friday, 20 June 2025

National Limits, European Claims: The Ultra Vires Conflict in EU Constitutional Law (part 2)

 



Dr Benedikt Riedl, Mjur (Oxford),  postdoctoral researcher and academic assistant at the Chair of Public Law and Legal Philosophy (Prof Dr Peter M. Huber, former Justice of the Federal Constitutional Court and former Minister of the Interior) at LMU Munich.

Photo credit: Nicola Quarz, via Wikimedia Commons

 

Ultra Vires Review as a Legal Concept within EU Law

When disputes arise over the boundaries of EU authority, a deeper constitutional tension surfaces: Quis iudicabit – who gets to draw the final line? This question shapes one of the central controversies in EU law: the legitimacy and limits of ultra vires review.

The first part of the blogpost argued that ultra vires review is not an isolated or purely national phenomenon, but a widespread and constitutionally grounded legal practice across the EU. This second part goes further, arguing that ultra vires review is not only compatible with Union law but embedded within it. Anchored in the principle of conferral (Article 5(2) TEU) and safeguarded by Article 4(2) TEU, the authority of national constitutional courts to assess whether EU institutions have acted beyond their powers forms an integral part of the EU’s composite legal order. Rather than threatening the primacy of EU law, ultra vires review reinforces its democratic legitimacy by ensuring that integration remains bound by constitutional limits. To that end, this blogpost also sets out four cumulative steps for invoking ultra vires review as a concept of EU law – proposing a structured, treaty-compatible procedure designed to enhance mutual trust, legal certainty, and institutional balance across the European constitutional landscape.

Doctrinal classification of ultra vires review as a general principle of Union law

1 The authority of Member States’ constitutional courts to declare acts of EU institutions ultra vires – and, as a result, to deny them legal effect within the national legal system – constitutes a general legal principle of EU law. This conclusion is grounded in the EU’s foundations in public international law and supported by comparative constitutional analysis. The invalidation of legal acts that manifestly exceed EU competences follows from a systematic interpretation of the fundamental principles underlying EU law. Moreover, the EU Treaties contain no provision that prohibits Member States from conducting ultra vires reviews. Accordingly, ultra vires review should be understood as an established legal concept within the framework of EU law.

Principles of International Law: A Derived Legal System

2 The CJEU asserts the absolute autonomy of EU law without offering a clear normative foundation in the treaties or justification under the law as it stands (de lege lata). In reality, however, it is the national constitutions that provide both the foundational basis and the essential point of reference for EU law. This becomes evident through an analysis of the EU treaties and their historical development. The treaty text, treaty practice, and drafting history all consistently affirm this perspective. The treaty text includes numerous provisions that explicitly recognize the existence and evolution of the Union’s legal order as deriving from the will of the Member States. Treaty practice further reinforces this: several treaty amendments have failed due to the Member States’ refusal to ratify them. This shows that the EU legal order has never been truly autonomous; it has always been contingent on the voluntary political decisions of the Member States. The EU is based on the collective will of its Member States under international law. Its legal order draws its validity and legitimacy from the national acts of assent and the authorisation granted by Member States for the application of EU law. Only on this foundation can the EU legal order maintain the level of democratic legitimacy necessary for a direct connection to the citizens of the Member States.

3 Given the EU’s interconnected legal structure, the position adopted by the Member States is persuasive. It accurately reflects the constitutional reality of Europe: a union of open constitutional states committed – albeit sometimes cautiously – to cooperative judicial solutions. The constitutions of the Member States serve as both the legal foundation and the primary reference point for EU law. As a result, EU law and national constitutional law form a single, integrated legal system. Within this framework, ensuring effective legal protection is a shared responsibility – carried out through a cooperative network of constitutional courts, referred to as the Verfassungsgerichtsverbund in German legal scholarship.

4 Absolute primacy of EU law or the notion of an autonomous legal order cannot be established through subsequent practice or customary law for several reasons. First, the failure of the Constitutional Treaty clearly demonstrates a lack of political consensus among the Member States to codify a clause providing for the EU law’s absolute primacy. Second, due to the interconnected and multi-layered nature of EU law, Member States cannot be reduced to their governments alone. While governments may ratify treaty amendments without reservations, this does not take into account the constitutional courts, which act as additional constitutional authorities. Their jurisprudence must be taken into consideration in areas where legal orders overlap – and these courts have consistently rejected the idea of absolute primacy of EU law. Finally, customary law cannot emerge contra legem – that is, in contradiction to the express provisions of the EU treaties. As will become clear in the following, this may include Articles 2 TEU, 4(2) TEU, 5(2) TEU, 10 TEU, and 19 TEU.

5 Furthermore, the CJEU’s concept of autonomy is incompatible with its own jurisprudence. In Van Gend & Loos and Costa v. E.N.E.L., the CJEU explicitly grounded the primacy of EU law on the principle of conferral. Recently, however, the Court contradicted itself: It has invoked the unconditional ratification of amending treaties to support its position while simultaneously rejecting the justification of primacy based on a delegation of powers. The demands for uniformity and effectiveness of EU law do not justify arbitrary interference with Member States' constitutional identities. In summary, the concept of autonomy lacks both factual support and legal justification.

6 EU law does not derive its legitimacy from a constitutional act or any other foundational norm; instead, its legitimacy is functional rather than constitutional or supra-legal in nature. This limited and contingent basis for legitimacy distinguishes EU law from the constitutional systems of the Member States. As a result, EU law can only evolve into a genuinely autonomous legal order through a process of constitutionalisation by the European peoples – a process that has not yet taken place. The functional and pragmatic rationale underlying EU law, which is focused on practical effectiveness, neither establishes genuine autonomy nor justifies claims to absolute institutional or substantive authority.

7 Since EU law is not autonomous but derived from – and closely linked to – the constitutions and democratic will of the Member States, ultra vires review aligns with the foundational principles of EU law. Due to EU law’s character as a derived legal order, national courts may, in certain cases, review the application of secondary EU law and assess its validity within their domestic legal systems – especially when EU institutions exceed the competences conferred upon them by the Member States.

Comparative Constitutional Analysis: The Invalidation of EU Measures Exceeding Conferred Powers as a Core Legal Principle in Member State Constitutions

8 Comparative constitutional analysis demonstrates that ultra vires review is the procedural and institutional expression of a general constitutional principle: EU legal acts that exceed the competences conferred through the national parliaments’ acts of assent are not valid within the Member States. Here, national constitutional courts step in to conduct an ultra vires review when the CJEU fails to assess the limits of EU competences. By safeguarding the division of powers between the EU and Member States, these reviews uphold a fundamental constitutional principle. While national constitutions refer to this principle in different terms – such as sovereignty, the republican form of government, democracy, or popular sovereignty – they all serve the same functional purpose: to ensure the democratic legitimacy and internal coherence of EU measures within the national legal order.

9 From a formal standpoint, ultra vires review implements the principle of limited conferred powers in a procedural way. It builds on the widely accepted legal principle that actions beyond conferred competences are prohibited. The EU’s lack of competence-competence (Kompetenz-Kompetenz) – i.e. its inability to unilaterally define the scope of its own powers – is explicitly affirmed in Article 5(2) TEU. Since competences are transferred through acts of the Member States, all constitutional courts recognizing ultra vires review consider procedural enforcement of these limits a constitutional necessity. This ensures that the substantive principle of limited conferred powers is not left without procedural safeguards. This logic is also persuasive within the context of the European composite legal order: while no constitutional court disputes the CJEU’s authority to interpret the limits of EU competences, all reject the notion that the CJEU can unilaterally determine the boundaries of its own jurisdiction. The domestic legal consequences of such determinations are governed by each Member State’s acts of assent. In any event, the CJEU has not been granted the ultimate authority to define or transform the constitutional orders of the Member States.

10 In substantive terms, ultra vires review serves to protect both popular and state sovereignty. Its justification lies in the idea that when EU institutions overstep their competences, they undermine democratic accountability and violate the right of citizens in the Member States to self-determination. Political self-determination is understood both individually and collectively, as tied to the state. The core issue remains the same: if EU institutions act beyond their conferred powers, those actions lack a proper legal basis and, consequently, democratic legitimacy. These acts intrude upon the regulatory autonomy of the Member States and the democratic self-determination of their citizens. Ultimately, it is up to the sovereign – the citizens of the Member States – to decide whether and to what extent EU law applies within their national legal systems. This is determined by the respective parliaments through their acts of assent, which define the scope of EU law within the national constitutional framework via the so-called “integration programme.” Under a compelling interpretation, ultra vires review thus acts as a procedural safeguard of the European peoples’ right to self-determination ensuring the democratic responsiveness of EU law to every citizen. At the same time, it enables the very transfer of sovereign powers, without which the democratic principle itself could be placed at risk.

Article 5(2) TEU: The Composite Structure and Constitutional Anchoring of EU Law

11 EU law and national constitutional law form an integrated legal system. The European Union is a union of constitutional states open to legal integration and cooperation. European secondary law and national law are structurally interconnected through the framework of European primary law. Accordingly, the constitutions of the Member States contribute to an interlinked constitutional order. Legal questions that arise at the intersection of different legal systems must therefore be assessed in light of the mutual interdependence between national law and EU law. The principle of conferral has both a European and a national dimension and is therefore of dual nature. At the European level, it is enshrined in Article 5(2) TEU; at the national level, it is implemented through constitutional opening clauses and acts of assent authorising the application of EU law. In EU law, this principle reflects the limited transfer of sovereign powers from the Member States to the Union. As such, it is not solely a principle of EU law; it also incorporates into primary law the constitutional reality of the Member States and the EU’s dependence on their sovereign decisions under international law. Like Article 4(2) TEU, it expresses both the constitutional origin and the composite nature of the Union’s authority.

12 Moreover, the CJEU itself is directly bound by the principle of conferral, as evidenced by Article 19 TEU. The limited scope of its judicial mandate – in both competence and legitimacy – is clearly articulated in the EU Treaties: Article 19(1), first subparagraph, sentence 2 TEU states that the CJEU ensures the observance of the law "in the interpretation and application of the Treaties," while Article 19(1), second subparagraph TEU limits effective legal protection to "the fields covered by Union law." In this way, the European judicial system reflects the EU’s compound structure. The interconnection of judicial systems operates in both directions: the CJEU is integrated into the judicial framework of the Member States, and national courts are functionally embedded in the enforcement of Union law. Legal protection within this network of constitutional courts is established in the EU Treaties as a shared responsibility between the CJEU and the constitutional courts of the Member States.

13 The involvement of national constitutional courts in the ultra vires procedure is the procedural and institutional consequence of the dual nature of the principle of conferral. Since questions of competence arise in both the EU sphere (interpretation of EU law) and the Member State sphere (interpretation of the integration programme and constitutional opening clauses), resolving such conflicts requires cooperation between the CJEU and national constitutional courts in accordance with Article 19 TEU. The procedural treatment of ultra vires conflicts thus reflects the multidimensional nature of the primacy of EU law and must therefore be addressed institutionally at both levels – by the CJEU as well as the national constitutional courts.

14 The transfer of competences to the EU takes place through national legal acts in accordance with constitutionally prescribed procedures and therefore logically precedes any consideration of the primacy of EU law. These constitutional parameters – reflected in the EU Treaties, particularly in Article 5(2) and Article 19 TEU – form the basis for the residual competence of national constitutional courts to review the boundaries of conferred powers. In principle, Member States have entrusted the CJEU with this competence of review, and national constitutional courts can rely on the CJEU to fulfil it in accordance with Article 19(1), subparagraph 2 TEU. However, if the CJEU fails to adequately exercise its control function, national constitutional courts retain a fallback responsibility to safeguard the proper delineation and exercise of competences. Absent this fallback mechanism, they would ultimately be stripped of their original role of protecting the national constitution and identity, reducing their function to a mere absurdity. The ultra vires procedure – while primarily vested in the CJEU and exercisable only as a last resort by national constitutional courts – derives directly from the principle of conferral embedded in the acquis communautaire of EU law.

Democratic principles and the context of legitimacy in the European Union

15 The involvement of national constitutional courts in ultra vires procedures can be justified not only by the principle of conferral but also by invoking Article 2 TEU and the democratic principles underpinning the European Union. This argument is based on the role of national parliaments and the principle of conferred powers. It underscores the fact that when EU institutions act beyond their competences, the essential link of democratic legitimacy between the Union's authority and the citizens of the Member States is compromised. In such instances, the control conducted by constitutional courts serves as a necessary corrective to uphold the democratic foundation of the EU.

16 The European Union derives its democratic legitimacy through two channels: the European Parliament (Article 10(2) subpara. 1 and Article 14 TEU) and national parliaments (Article 10(2) subpara. 2 and Article 12 TEU). The EU's well-documented democratic deficit – characterised by issues such as unequal voting rights, an insulated executive branch, and limited public engagement – is mitigated by the Member States’ respective democracies, particularly through their national parliaments. These parliaments play a crucial role in legitimizing the EU. A distinction can be drawn between the European Parliament’s direct exercise of democratic functions and the national parliaments’ broader responsibility for overseeing the integration process. If EU institutions overstep their competences and thereby undermine the authority of national parliaments, one of the foundational pillars of European democracy is weakened, resulting in a decline of democratic legitimacy for the EU as a whole.

17 The principle of conferral is closely tied to the democratic values enshrined in Article 2 TEU. A core element of the EU’s democratic framework is the concept of legitimacy based on competences. As a derived legal order, the EU is legitimised through the competences conferred upon it. The democratic principles of the Union go beyond a purely formal notion of authority based on the transmission of the citizens’ will into institutional power. Instead, they require a substantive, effective realisation of that will – specifically, the guarantee of genuine popular sovereignty. Grounded in the principle of conferral and reinforced by Article 4(2) TEU, the EU legal order itself respects the legislative authority of national parliaments and the democratic will of the citizens in the Member States.

18 Ultra vires review plays a pivotal role in preserving democratic legitimacy within the European Union – specifically, the legitimacy that flows through the parliaments of the Member States. Its primary function is to uphold democracy within the European network of states, constitutions, legislative bodies, administrations, and judicial systems. By monitoring the limits of conferred competences, ultra vires review serves as a safeguard or compensatory mechanism critical for upholding democracy – in other words, it is democracy-specific. This is particularly significant for preserving individuals’ rights to self-determination. In the context of European supranational integration, ultra vires review exposes the diffusion of political responsibility, thereby promoting greater transparency and accountability in decision-making by EU institutions.

19 In principle, the CJEU is responsible for ensuring compliance with the division of competences within the EU. Even if a decision is incorrect, a competence review has still taken place. However, if a decision by the CJEU no longer meets the required methodological standards, the review is reduced to a merely formal check. In such cases, the substantive core of the European understanding of legitimacy is no longer upheld. At the same time, Article 2 in conjunction with Article 5(1) and (2) TEU allows for a decentralised review of competences by constitutional courts in the Member States. These courts supervise the boundaries of the EU’s derived authority to safeguard the substantive foundations of democracy – namely, meaningful parliamentary influence and effective popular sovereignty.

Rule of Law and Separation of Powers in the Judicial System

20 Several factors have contributed to the CJEU's de facto position as an almost unchecked authority within the EU legal order. These include the constitutionalisation of EU law, its limited embeddedness in a European public sphere, the CJEU’s dual role as both a constitutional and specialised court, the absence of sector-specific competence rules, and its broad, teleological approach to interpretation. This situation is further exacerbated by the fact that the CJEU increasingly positions itself not as the “guardian” of the EU legal order, but as the “engine of integration.” In this role, it applies double standards in its judicial review of competences: When reviewing infringements of EU law by Member States, the CJEU exercises strict scrutiny. By contrast, in cases where EU institutions themselves exceed their competences, it displays significant leniency. To date, the CJEU has found an overreach of competences by EU institutions only in four cases. In some judgments, the level of scrutiny applied to EU bodies is so minimal that it amounts to a superficial or merely evidentiary review. This approach conflicts with the EU’s commitment to representative democracy under Article 10(1) TEU, the right to effective legal protection, and the obligation to examine facts under Article 47 CFR and Articles 6 and 13 ECHR. This jurisprudence has contributed to a gradual shift of competences toward the EU without any formal treaty amendments. As a result, it undermines the legal basis of institutional action and weakens formal legitimacy within the EU. The expanding scope of EU competences, without a corresponding increase in democratic legitimacy, also diminishes the Union’s substantive legitimacy.

21 Within the European judicial system, the CJEU regards itself as the highest authority, positioned above the national constitutional courts. While the Court has repeatedly acknowledged both the EU’s lack of statehood and the limited scope of its competences, it nonetheless expands its jurisdiction into core areas of national constitutional law – thereby infringing upon the jurisdictional authority of the Member States' highest courts. This leads to a growing disconnect between the principles of direct applicability and primacy of EU law, on the one hand, and the foundational principle of conferral, on the other. It also results in EU law penetrating the most protected spheres of national constitutional orders. In doing so, the CJEU disregards the jurisprudence of national constitutional courts – even in areas where EU law and national constitutional law are closely interlinked.

22 In this context, ultra vires review plays a key role in safeguarding the separation of powers and establishing checks and balances within the European network of constitutional courts. A judicial equilibrium between the EU and the national level can be maintained through disagreement as well as ongoing dialogue. Clearly defining the limits of competence enhances legal certainty and builds trust in future steps toward integration. Moreover, ultra vires review offsets the CJEU’s limited capacity for internal control within the European constitutional system – a limitation resulting from the absence of a judicial hierarchy, insufficient public scrutiny, lack of opposition, and constrained legislative oversight. At the same time, it acts as a safeguard, protecting national constitutional systems from an unchecked assertion of EU authority.

Article 4(2) TEU: Protecting Constitutional Identity as a Systemic Exception to the CJEU’s Exclusive Authority to Invalidate EU Acts

23 Article 4(2) TEU directly reflects the considerations outlined above, which stem from the EU’s compound constitutional structure. This provision can be understood as implicitly acknowledging that, in strictly limited and extraordinary situations, Member States may invoke ultra vires review. As will be shown below, such an interpretation does not conflict with the general principles of EU law, but rather takes into account the structural diversity and constitutional identity of the Member States. Article 4(2) TEU may therefore be read as establishing a system-inherent exception to both the primacy of EU law and the CJEU’s exclusive jurisdiction to invalidate Union acts. In rare cases, this exception could be asserted procedurally through an ultra vires review, serving as a last-resort safeguard within the broader framework of European legal integration.

24 Article 4(2) TEU stipulates that “the Union shall respect the equality of Member States before the Treaties as well as their national identities, inherent in their fundamental structures, political and constitutional, inclusive of regional and local self-government.” Fundamental constitutional structures within the meaning of Article 4(2) TEU can encompass a wide range of core constitutional principles, including specific expressions of democracy or the rule of law in Member States. However, the CJEU’s case law on the extent to which Member States may define and invoke their own constitutional identity remains inconsistent and highly context-dependent. For instance, in the M.A.S. and M.B. rulings involving the Italian Constitutional Court, the CJEU showed cautious openness to national constitutional reservations and signalled a willingness to engage in dialogue with national constitutional courts. In contrast, in cases involving the Romanian Constitutional Court’s constitutionally controversial jurisprudence, the CJEU rejected the admissibility of both identity review and ultra vires review under EU law.

25 The interpretation of the wording, structure, history, and purpose of Article 4(2) TEU confirms its character as a reference to national constitutions and the authority of national constitutional courts to define constitutional identity. The wording – which states that national identity is expressed “in their” fundamental constitutional structures – clearly points to domestic constitutions as the relevant legal source. Structurally, the provision complements Articles 4(1) and 4(3) TEU and establishes a binding limit on the Union’s integrative reach. Historically, the travaux préparatoires of the Constitutional Treaty show that responsibility for safeguarding constitutional identity was deliberately left to the Member States, in order to prevent a creeping expansion of EU competences. In terms of purpose, Article 4(2) is meant to protect core constitutional choices from being overridden by Union law. It functions similarly to self-judging clauses in international law, which allow states to make their own determinations, subject only to limited review. In this way, the provision establishes a direct link between Union law and national constitutional law and forms a key element of the EU’s composite constitutional structure. As a counterpart to national identity clauses such as Article 79(3) of the German Basic Law, Article 89(5) of the French Constitution, or Article 9(2) of the Czech Constitution, it opens Union law to core components of national constitutional orders. Defining what constitutes national identity ultimately falls to national constitutional courts, in line with the division of responsibilities in the European constitutional court network, while the CJEU is limited to checking for arbitrariness or abuse.

26 In narrowly defined exceptional cases, Article 4(2) TEU leads to a systemic suspension of the primacy of EU law and constitutes a procedural exception to the CJEU’s monopoly of interpretation. This consequence is inherent in Union law itself, since both the principle of conferral and the protection of national constitutional identity define structural limits to the scope of primacy. In narrowly defined exceptional cases, Article 4(2) TEU leads to a systemic suspension of the primacy of EU law and constitutes a procedural exception to the CJEU’s monopoly of interpretation. This consequence is inherent in Union law itself, since both the principle of conferral and the protection of national constitutional identity define structural limits to the scope of primacy. While the obligation to respect national identity under Article 4(2) TEU is generally relative, it becomes absolute where the core elements of constitutional identity are at stake. This core includes those values, structural principles, and norms that, under a Member State’s own constitutional order, are categorically excluded from being transferred to the Union – either because they are formally entrenched or because they are considered non-transferable in structural terms. Even where national constitutional principles coincide with the fundamental values enshrined in Article 2 TEU, their particular national expression enjoys absolute protection, precisely because those values themselves hold overriding importance within Union law. What matters is not whether the national constitution contains an explicit eternity clause, but whether – according to the domestic constitutional understanding – it defines an inviolable sphere of sovereign self-determination. In such cases, the obligation to respect national identity is not subject to balancing or proportionality review. Accordingly, the Member State’s interest in safeguarding this core outweighs the Union’s interest in legal uniformity. While disregarding such identity would amount to a systemic violation of constitutional self-government, the legal consequence within Union law – namely, the inapplicability of the respective EU measure in that Member State – is a limited and acceptable cost. The resulting impairment of uniformity and effectiveness is consistent with the nature of the EU’s legal order, particularly since the ultra vires review, as an expression of democratic self-determination, also serves the values enshrined in Article 2 TEU. It is therefore grounded in primary law via Article 4(2) TEU and constitutes a necessary procedural exception within the non-hierarchical, pluralistic structure of the European constitutional order.

27 It has long been assumed that only the identity review in the narrow sense corresponds procedurally to this provision. However, as comparative constitutional analysis shows, the ultra vires review – understood as a democracy-protecting form of identity review – is also embedded in the constitutional structures of numerous Member States. This applies particularly where it serves, as in the German and Czech constitutional traditions, to safeguard popular sovereignty or sovereign statehood. A qualified overreach of competences breaks the necessary link of democratic legitimacy between Union action and the national constitutional order, thereby infringing upon the constitutionally protected core of democratic identity. In such cases, the ultra vires review functions as the procedural mechanism for preserving this core, and must therefore be regarded not only as an expression of domestic identity clauses – such as Article 79(3) of the German Basic Law or Article 9(2) of the Czech Constitution – but also as a review mechanism permitted under Union law by virtue of Article 4(2) TEU. The jurisprudence of various national constitutional courts confirms this classification. Ultra vires review thus constitutes a procedurally legitimate expression of the Union’s obligation to respect national identity, reflecting both the multidimensional nature of the primacy principle and the institutional logic of the European constitutional court network.

No exclusion on the basis of conflicting EU law

28 From the CJEU’s perspective, ultra vires review by Member State constitutional courts violates EU law for several reasons: it threatens the uniformity and effectiveness of EU law, challenges the CJEU’s exclusive authority to declare EU acts invalid, and undermines the principle of equality among Member States and their citizens. However, these objections are not convincing from a doctrinal and legal-theoretical standpoint.

29 Ultra vires review does not undermine the CJEU’s exclusive authority to annul EU legal acts. While both the jurisprudence established in the Foto-Frost judgment and Article 267(1)(b) TFEU prohibit national courts from declaring EU acts invalid, national courts are not categorically barred from examining whether such acts exceed the competences conferred on the EU. When a national constitutional court reviews the scope of EU law on the basis of its act of assent, it applies a distinct standard – as confirmed by comparative constitutional law. This is not a parallel review of EU law, but a narrowly limited control, typically confined to manifest excess or arbitrary transgression of conferred competence. On the remedial level, a finding that an EU act is ultra vires does not invalidate it across the European Union; it merely renders the act inapplicable within the respective national legal order. Furthermore, the strict separation between the procedural question of Quis iudicabit? and the substantive principle of conferral appears to be a politically motivated construct – one that effectively grants the CJEU de facto authority over the very scope of its own powers (i.e. the judicial competence over competences).

30 Moreover, isolated ultra vires reviews can, in fact, strengthen the EU legal order in the medium and long term. They help build trust in the European integration process, as Member States are more willing to transfer additional competences when assured that the limits of such transfers will be respected. Conversely, if competences gradually extend beyond their original conferral, thereby weakening the link between direct applicability and the principle of conferral, the effectiveness and credibility of EU law risk being undermined.

31 The Member States have not – and, indeed, could not – conferred upon the CJEU the authority to determine the limits of its own judicial competence, as doing so would inherently restrict their own constitutional identity and spheres of competence. This is because the constitutional core of most Member States, often entrenched or unamendable, impose strict limits on the transfer of sovereign powers. The constitutional clauses authorizing the application of EU law only extend to acts adopted within the limits of conferred competences and consistent with national constitutional identity. This logic is reflected in Article 19(1), second sentence, TEU, which explicitly ties the CJEU’s jurisdiction to the principle of conferral.

32 Despite the CJEU’s recent explicit rejection of ultra vires review – albeit in the context of rulings involving constitutionally compromised courts – its judgment in M.A.S. and M.B. (Taricco II, 5 December 2017) contains indications that the Court acknowledges the legitimacy of constitutional review reservations. This effectively amounts to an exception to its asserted exclusive authority over competence disputes (judicial competence over competences). The ruling suggests a de facto recognition of identity review or, at the very least, a greater deference to national constitutional identity when weighed against the primacy and uniform application of EU law.

33 The CJEU’s new line of reasoning – seeking to justify absolute primacy and a comprehensive monopoly of jurisdiction through the principle of equality in Article 4(2), sentence 1 TEU – suffers from fundamental methodological flaws and is therefore unconvincing from the outset. It misinterprets the wording of Article 4(2) TEU, which imposes obligations solely on the Union, not on the Member States, ignores the internal structure of the provision, which expressly balances the equality of Member States with the respect for their national identities, and disregards its purpose as a protective provision in favour of the Member States rather than as a tool to expand Union competences. Moreover, it rests on a misapprehension of the function of the principle of equality within the EU legal order. Where a situation falls outside the scope of Union law, the principle of equality derived from it is inapplicable from the outset. Accordingly, the CJEU’s argument is circular, because ultra vires review, by definition, concerns precisely those cases where Union law is not applicable.

34 Since ultra vires review is not only compatible with the EU Treaties but also rooted in them, the involvement of national constitutional courts should be recognized as a general principle of EU law. Ultra vires review is grounded in the foundations of international law and the constitutional evolution of the EU legal order. It represents a procedural and institutional expression of the dual nature of the principle of conferral and safeguards the separation of powers within the constitutional court system – particularly, with respect to the legitimacy of European democracy. This review mechanism is justified under Article 4(2) TEU as a treaty-based exception to the CJEU’s exclusive authority to annul EU acts. As a legal concept, the ultra vires procedure reflects the compound structure of the EU, composed of interlinked constitutional systems and courts. Given the exceptional nature of this general legal principle, both the burden and the authority to justify invoking ultra vires review rest with the constitutional and supreme courts of the Member States. This approach creates a balanced legal framework that preserves the effectiveness and uniform application of EU law, while ensuring that ultra vires reviews remain legally contained and subject to clear procedural safeguards.

 

In summary, ultra vires review should be recognised as a structural element of the European legal order. As a procedural expression of the principle of conferral and as a safeguard for constitutional identity under Article 4(2) TEU, it serves a critical democratic and legal function. Rather than contradicting Union law, it preserves the legitimacy of EU integration by ensuring that the division of competences remains constitutionally anchored. The next and final part of this blogpost will examine how ultra vires review can be institutionalised within the existing framework of EU law – not as a threat to legal unity, but as a mechanism for structured constitutional dialogue.

Institutionalising Ultra Vires Review: The Four-Tier Test for Constitutional Courts

The following analysis outlines four cumulative stages that must be observed when invoking ultra vires review within the European constitutional framework. Rather than undermining the primacy of Union law, this structured procedure enhances mutual trust and legal certainty among Europe’s constitutional courts. It clarifies the limited and exceptional conditions under which national courts may act as guardians of their constitutional mandates – while safeguarding the rule of law, democratic legitimacy, and the institutional balance of the EU’s composite legal order.

 

1 The involvement of Member State constitutional courts in the common ultra vires procedure is based not only on their respective national constitutions and acts of assent, but also on Articles 2, 5(2), and 4(2) TEU. Read together with Articles 4(3) and 19 TEU, these treaty provisions give rise to four substantive requirements – or stages – of the ultra vires procedure as a legal concept under EU law. First, there must be a violation of the principle of conferral or of the integration programme as enshrined in Articles 5(2) and 4(2) TEU. At every stage, ultra vires review must comply with the principle of sincere cooperation (Article 4(3) TEU), respect the judicial function of the CJEU pursuant to Article 19 TEU, and fulfil its role as a democratic safeguard mechanism in line with Article 2 TEU, ensuring the legitimacy of EU action.

2 At the first stage, there must be a legal act that exceeds the competences conferred upon the EU. An ultra vires act exists where EU institutions act without a proper legal basis, go beyond the conditions set for the exercise of their powers, or breach prohibitive norms, thereby infringing on the competences of the Member States. It is important to note that neither the obvious nature nor the particular gravity of a competence breach is a requirement under EU law; such thresholds cannot be derived from Article 5(2) TEU. In preliminary ruling proceedings under Article 267 TFEU, it is sufficient for a national constitutional court to have doubts about whether an EU measure falls within the Union’s competences. If the court considers the case to involve an ultra vires act, it refers the question concerning the scope of Union law to the CJEU. The ultra vires procedure thus initially differs from an ordinary preliminary reference only in that it is triggered not by any legal error, but specifically by a suspected overstepping of competences. The decisive difference arises only at the stage of assessing the CJEU’s response – namely, in the standard of review applied in ultra vires control.

3 At the second stage, the constitutional courts of the Member States and the CJEU are required to cooperate and engage in judicial dialogue within the framework of the preliminary ruling procedure. From the perspective of EU law, ultra vires review necessitates the involvement of the CJEU in the decision-making process, as provided by Article 4(3) first subparagraph, Article 19 TEU, and Article 267 TFEU. From the perspective of national constitutional law, this cooperation is equally required due to the constitutions’ openness to European law. As a result, the ultra vires procedure constitutes a matter of shared responsibility, which can only be fulfilled through mutual cooperation and constructive dialogue in the context of the preliminary ruling process.

4 This requires the constitutional courts of the Member States to submit a clear and well-reasoned question to the CJEU, providing all the necessary elements for the Court to reach a conclusive judgment on the ultra vires issue. The submission must include detailed legal arguments indicating a possible overreach of competences. This transparency is essential for resolving a competence dispute through legal reasoning. There must be a realistic opportunity for one court to recognise the other’s legal position as methodologically sound – or even to be persuaded by it. A notable example of this cooperative approach is the GCC’s referral in the OMT case. The GCC comprehensively explained why it believed the OMT decision violated Article 119 TEU, Article 127(1) and (2), and Article 123 TFEU. At the same time, it demonstrated its willingness to cooperate by allowing room for the CJEU to interpret the legal issues in a way that aligned with its conferred competences, thereby upholding the spirit of judicial dialogue within the preliminary ruling procedure.

5 At the third stage, the CJEU is responsible for interpreting EU law, though its decisions remain subject to methodological scrutiny by the constitutional courts of the Member States. If a ruling fails to meet methodological standards, the CJEU exceeds its mandate under Article 19 TEU and may be overruled through ultra vires review. The CJEU’s authority to interpret EU law is derived from the Member States via the act of assent, as codified in Article 19(1) subparagraph 1, sentence 2 TEU. However, this authority is no longer democratically legitimised if the interpretation goes beyond what Member States could reasonably foresee when granting assent; this is particularly the case when the CJEU tends to judicial legislating rather than interpreting the law. The CJEU clearly oversteps its jurisdiction when it fails to respect the methodological boundaries of judicial interpretation. This lack of methodological appropriateness can take several forms: (a) contradictions and inconsistencies in case law that affect the outcome, (b) disregard for standard methods of legal interpretation, (c) failure to engage with arguments raised by the referring court, (d) arbitrary judicial development, and (e) complete neglect of constitutional standards in its review. In such cases, the effective control of jurisdiction is no longer ensured, and the fallback function of national constitutional courts is reactivated as to protect the division of competences and uphold the legitimacy of EU action.

6 The CJEU’s Weiss judgment illustrates an ultra vires ruling that lacks methodological appropriateness due to internal contradictions and inconsistencies (a). Specifically, the Court applied the proportionality test to EU institutions in a far more superficial manner – without justification – than it typically does when reviewing acts by Member State authorities. Furthermore, the CJEU’s complete disregard for the economic policy implications of the PSPP conflicted not only with its reasoning in Gauweiler but also with its general approach in other areas of EU law.

7 A further serious methodological error (b) lies in the CJEU’s failure to apply the established methods of legal interpretation – such as textual analysis, historical context, systematic structure, teleological reasoning, and comparative law. The constitutional traditions of the Member States set boundaries for European legal methodology and require that the CJEU’s interpretative approaches remain consistent with these traditions. CJEU rulings must be sufficiently reasoned to allow for public scrutiny and review by other courts, as mandated by Article 36(1) of the CJEU Statute and Article 87(m) of the CJEU Rules of Procedure. If the CJEU disregards relevant facts or the arguments raised by parties to the case, this may result in legally unintelligible outcomes. A notable example is the Landtová judgment, in which the CJEU ignored both the wording of the European Migrant Workers Regulation and the historical context surrounding the dissolution of Czechoslovakia.

8 Based on its judicial function under Article 19 TEU and the principle of sincere cooperation, the CJEU is required to provide a sufficiently reasoned response to preliminary references, particularly regarding alleged breaches of competence (c.). The third category of judgments that fails to meet methodological standards thus consists of CJEU rulings that do not adequately address the concerns raised by the referring constitutional or supreme court. A key example is the CJEU’s ruling in Weiss. Among other issues, the GCC asked whether the PSPP infringed Article 119, Article 127(1) and (2) TFEU, as well as Articles 17–24 of the Protocol on the Statute of the ESCB and the ECB. The GCC identified the ECB’s failure to properly assess the proportionality of its measures as a central issue in determining whether it had acted within its competence. Specifically, the GCC was concerned about the economic policy effects of the ECB’s measures, which had previously gone unexamined. However, the CJEU did not take these detailed objections seriously and failed to engage with the economic impact in a thorough or coherent way. As a result, a proper proportionality assessment, in line with established legal methodology, was not carried out.

9 Fourth, arbitrary judicial lawmaking constitutes a case of methodological failure (d.). A clear example is the CJEU’s Mangold judgment, where the Court “created” the Union law principle prohibiting age discrimination based on a questionable and insufficient comparative analysis, without identifying a clear textual, structural, or historical basis in the Treaties. This overstepped the permissible bounds of judicial interpretation, amounting instead to an unauthorised amendment of primary law. Legitimate judicial development of the law serves to fill unintended gaps, resolve conflicts of fundamental values, and ensure fair adjudication in individual cases, but it is strictly limited: it must not result in legislative correction, encroach upon areas reserved for political decision-making, or undermine the principle of conferred powers. Furthermore, any judicial development must meet heightened requirements of justification; the comparative analysis must be comprehensive, transparent, and logically coherent, and particular care must be given to respecting the division of competences between the Union and the Member States.

10 The fifth category in which the CJEU manifestly exceeds its jurisdiction arises when it fails to fulfil its institutional judicial role and thereby falls short of the constitutional standards enshrined in Article 19 in conjunction with Article 2 TEU. This occurs, for example, when the Court fully or partially fails to fulfil its duty of judicial review – particularly with respect to executive or independent institutions – or when it applies the intensity of review arbitrarily (e.). A clear example of this is once again the Weiss judgment, where the CJEU effectively abdicated its judicial oversight role by conducting only a cursory review limited to assessing whether the ECB had committed “obvious” overreaches of its mandate. The Court merely asserted the proportionality between monetary policy measures and their economic consequences, rather than actually examining their consequences. This represents a fundamental methodological error: proportionality between ends and means cannot be meaningfully affirmed without first identifying and evaluating the actual effects. Such an examination was not even possible in this case, as the CJEU never clearly identified the economic implications of the ECB’s actions. This fifth category of judgments, which depart from established legal methodology by neglecting rule-of-law standards in judicial review, directly underscores the need for ultra vires control. It serves to prevent gradual, unchecked shifts of power towards the EU level and safeguards Member States’ authority over their own competences as well as the democratic self-determination of their citizens.

11 Although ultra vires review is a tool for safeguarding the legitimacy of EU action, it must be understood within the broader context of EU law. It is rooted in the democratic principles of the European Union and contributes to maintaining the separation of powers and upholding the rule of law. Therefore, its legitimacy and application – especially during the fourth stage of the procedure – are tied to compliance with the rule-of-law requirements set out in Article 2 TEU.

12 Constitutional courts retain a limited degree of discretion in interpretation and judgement. This means that, in exceptional cases, both the activation and rejection of ultra vires review by different Member State constitutional courts may be permissible with respect to the same legal issue. This outcome is also consistent with the EU’s interconnected legal structure, particularly given that the CJEU’s jurisdiction is derivative and, unlike the constitutional courts of the Member States, the CJEU does not possess the competence to determine the scope of its own powers.

13 Article 2 TEU implies a specific prohibition of abuse of rights within Union law, which also limits the scope of ultra vires review. Such review is only permissible where it serves its purpose of safeguarding democratic legitimacy within the Union through constitutional courts of the Member States. It becomes abusive – and therefore contrary to Union law – where it is functionally disconnected from that purpose, for example: (1) where the subject matter is not clearly limited, (2) where the ruling is not embedded in a consistent, EU-friendly line of jurisprudence, (3) where the judiciary is visibly instrumentalized by the executive, or (4) where the legal consequences are left unclear and risk systemic disruption. In these cases, the review no longer safeguards constitutional identity but undermines the legal order. The CJEU may intervene in such situations but is limited – under Article 4(2) and Article 4(3) TEU – to a review for abuse or arbitrariness, following a good faith standard.

14 Ultra vires review must also be understood within the broader context of the horizontal network of constitutional courts. It should not be viewed in isolation but in light of the shared constitutional traditions and judicial decisions of the Member States. This requires mutual consideration of rulings by other constitutional courts. Any departure from these decisions must be appropriately justified and take into account both national and EU legal perspectives. Such an approach ensures coherence in judicial reasoning and alignment with European values and legal principles.

15 In summary, ultra vires review should be understood as a shared responsibility within the European network of constitutional courts. Legally, Member State constitutional courts retain ultimate authority to deliver final judgments concerning their own legal systems. At the same time, the CJEU holds a “right of first access” based on its interpretative monopoly, enabling it to resolve the vast majority of jurisdictional disputes with legal certainty. However, this presupposes that the CJEU exercises a level of judicial scrutiny that genuinely safeguards the principle of conferral and, by extension, the (national) sovereignty of the Member States. This division of roles aligns with the institutional functions of the CJEU and the constitutional courts in the European constitutional court system. The CJEU, as the Union’s court, is responsible for interpreting and ensuring the effectiveness of EU law and is particularly well positioned to do so given its institutional proximity to Union-level issues. In contrast, the constitutional courts of the Member States are not tasked with reinterpreting EU law, but rather with safeguarding national constitutional identity. By observing this task, they also preserve the coherence of the EU’s heterogeneous and pluralistic constitutional value system.

16 The following thesis may serve as a forward-looking conclusion: The GCC’s PSPP judgment may well be remembered as the starting point for establishing effective competence control as a shared responsibility at the level of EU law. Just as the GCC’s Solange I case law was initially met with strong criticism but ultimately played a key role in developing robust European fundamental rights protection, a similar evolution may now be underway. The growing legal conviction among Member States’ constitutional courts – that they may invoke democracy-protecting constitutional reservations such as ultra vires review – is likely to motivate the CJEU to fulfil its institutional judicial role with greater rigour, particularly in complex jurisdictional matters at the intersection of the European composite legal order. In doing so, the CJEU can contribute meaningfully to enhancing legal certainty and legal confidence across the EU – two foundational elements of the rule of law and key drivers of European integration in a legal community. At the same time, it remains evident that if the CJEU consistently and credibly reviews the limits of competences under EU law, the constitutional courts of the Member States will have no cause to resort to ultra vires review.

Ultra vires review is not a relic of constitutional nationalism, but a structured expression of judicial responsibility in a pluralistic Union. When invoked under the four cumulative conditions identified in this part – (1) a manifest breach of conferred powers, (2) sincere judicial dialogue through the preliminary reference procedure, (3) a demonstrable failure of the CJEU to meet the standards of legal methodology, and (4) compliance with the democratic and rule-of-law principles of Article 2 TEU – it strengthens rather than weakens the authority of EU law. These requirements ensure that ultra vires review is not exercised arbitrarily but remains embedded in a framework of institutional cooperation, interpretative discipline, and mutual respect. Properly understood, ultra vires review complements the role of the CJEU by acting as a constitutional backstop: it upholds the foundational balance between Union effectiveness and Member State sovereignty. If the CJEU fulfils its institutional role with methodological clarity and judicial restraint, ultra vires review will remain what it was always meant to be – a principled exception, not a systemic threat.

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