EU Constitutionalism

Constitutionalisation of the Treaties

The process of constitutionalisation of the EU Treaties describes the progressive transformation of international treaties establishing economic integration into a constitutional legal order possessing the essential characteristics of a constitutional system. This process, driven primarily by the case law of the Court of Justice, has endowed the Treaties with attributes traditionally associated with national constitutions: direct effect, supremacy, fundamental rights protection, and judicial review.

The foundational constitutional judgments of the CJEU in the 1960s and 1970s established the core elements of the EU constitutional order. In Van Gend en Loos (1963), the Court held that the Treaty constituted a new legal order conferring rights on individuals, rejecting the traditional international law paradigm in which only states were subjects. In Costa v ENEL (1964), the Court asserted the supremacy of Community law over conflicting national law, regardless of the hierarchical status of the national provision. In Internationale Handelsgesellschaft (1970), the Court declared that respect for fundamental rights forms an integral part of the general principles of Community law, filling the constitutional gap created by the absence of a written bill of rights.

The Treaty of Lisbon (2009) completed the formal constitutional architecture by conferring legally binding status on the Charter of Fundamental Rights (Article 6(1) TEU), providing for EU accession to the European Convention on Human Rights (Article 6(2) TEU), establishing the legal personality of the Union (Article 47 TEU), and codifying the procedures for withdrawal from the Union (Article 50 TEU). Despite the rejection of the Constitutional Treaty in 2005, the Lisbon Treaty incorporated the substance of the constitutional project while avoiding the symbolic language of a European Constitution.

Multilevel Constitutionalism

The concept of multilevel constitutionalism provides a theoretical framework for understanding the EU legal order as a system in which constitutional authority is distributed across multiple levels — the national, the European, and the international — without any single level claiming ultimate hierarchical supremacy. Developed by scholars including Ingolf Pernice and Miguel Poiares Maduro, multilevel constitutionalism conceives of European integration as a process of constitutional synthesis in which national and European constitutional orders are intertwined and mutually constitutive.

Under this framework, the EU legal order does not replace national constitutions but supplements them, creating a constitutional Verbund (compound) in which constitutional authority is shared rather than allocated to a single sovereign. National constitutional courts retain the power to review EU acts for compatibility with fundamental constitutional principles, as articulated in the Solange jurisprudence of the German Federal Constitutional Court and the Taricco dialogue between the Italian Constitutional Court and the CJEU. The CJEU, for its part, asserts the autonomy and primacy of EU law within its sphere of competence, subject to respect for national constitutional identities under Article 4(2) TEU.

Multilevel constitutionalism rejects both the federal model, which presupposes a single constitutional sovereign, and the international law model, which treats the EU as a derivative legal order dependent on national constitutional authorisation. Instead, it describes a dynamic, interactive system in which constitutional principles emerge through dialogue and cooperation between courts and political institutions at different levels.

The Democratic Deficit Debate

The democratic deficit remains one of the most persistent normative challenges to EU constitutionalism. The critique holds that the EU suffers from a fundamental lack of democratic legitimacy because: the European Parliament, the only directly elected EU institution, does not function as a genuine legislative chamber with equal status to the Council in all legislative matters; the Council of Ministers operates largely through closed deliberations; the Commission, which holds the monopoly on legislative initiative, is not directly accountable to European voters; European elections are dominated by national rather than European political issues; and the EU lacks a European public sphere within which political debate and contestation can occur.

Defenders of the EU’s democratic legitimacy argue that the democratic deficit critique applies inappropriate state-based standards to a non-state polity. The EU, on this view, draws its democratic legitimacy not from a European demos but from the democratic character of its Member States, whose governments are represented in the Council and whose parliaments exercise scrutiny through the early warning mechanism of the subsidiarity protocol. The European Parliament provides a supplementary layer of democratic representation, and the EU’s decision-making processes incorporate extensive consultation, impact assessment, and transparency requirements.

The Lisbon Treaty introduced provisions designed to enhance the democratic legitimacy of the Union, including: Article 10 TEU, which provides that the functioning of the Union shall be founded on representative democracy; Article 11 TEU, which establishes principles of participatory democracy including the European Citizens’ Initiative; and Article 12 TEU, which strengthens the role of national parliaments in EU decision-making.

The Federal Analogy

The question whether the EU can be understood as a federal system has generated extensive theoretical debate. The EU possesses several characteristics commonly associated with federal states: a written constitution (the Treaties), a hierarchy of laws (supremacy), a federal court with compulsory jurisdiction (the CJEU), direct effect of federal law in constituent units, a central currency, and a common external trade policy. The EU also operates through the principle of conferral (Article 5 TEU), comparable to the enumerated powers of federal systems, and through the principles of subsidiarity and proportionality, which regulate the exercise of competences.

However, significant differences distinguish the EU from classical federal states. The EU lacks a central government with general competence over domestic affairs; its budget is small relative to GDP; it depends on Member States for the implementation and enforcement of its law; its legislative processes give member state governments a direct role through the Council; and its constituent units — the Member States — retain their own constitutions, armies, diplomatic services, and legal systems. The EU’s legal order is not grounded in a single constitutional founding moment but in an evolving treaty framework that depends on continuing consent of the Member States.

Federal theorists have proposed various characterisations: the EU as a federal union of states (the German Federal Constitutional Court in the Lisbon judgment), a federation in the making (Joseph Weiler), a cooperative federal system, or a quasi-federal polity. The ambiguity reflects the sui generis character of the EU, which resists classification within traditional categories of political organisation.

Constitutional Identity and the Taricco Saga

Article 4(2) TEU requires the Union to respect the national identities of Member States, encompassing their fundamental constitutional structures, political and constitutional systems, and essential state functions. The constitutional identity clause has been invoked by national constitutional courts to assert limits on the primacy of EU law, most notably in the jurisprudence of the German Federal Constitutional Court (Lisbon, PSPP, Next Generation EU) and the Polish Constitutional Tribunal (K 3/21).

The Taricco saga (Cases C-105/14 and C-42/17) illustrates the dynamics of constitutional identity dialogue between national courts and the CJEU. The CJEU initially held in Taricco I (2015) that Italian limitation periods in VAT fraud cases must be disapplied where they prevented the imposition of effective and dissuasive criminal penalties, relying on the obligation to protect the EU’s financial interests under Article 325 TFEU. The Italian Constitutional Court responded by referring a preliminary question challenging the CJEU’s interpretation on grounds of the fundamental constitutional principle of legality in criminal matters.

In M.A.S. and M.B. (Taricco II, 2017), the CJEU substantially modified its position, holding that the national court is not required to disapply national limitation periods where doing so would violate the principle that offences and penalties must be defined by law, a principle protected by Article 49 of the Charter and recognised as a general principle of EU law. The Taricco dialogue exemplifies the multilevel constitutional interaction in which the CJEU acknowledges the constitutional identity of Member States as a constraint on the otherwise primacy of EU law, requiring a balancing of European integration objectives against fundamental national constitutional principles.

Conclusion

EU constitutionalism describes a complex and contested normative order in which the Treaties have acquired constitutional characteristics while the EU continues to lack the institutional and political attributes of a state. The concepts of multilevel constitutionalism, the democratic deficit, the federal analogy, and constitutional identity provide competing theoretical frameworks for understanding and evaluating the EU’s constitutional development. The interaction between the CJEU and national constitutional courts, particularly in the context of constitutional identity claims, defines the dynamic and evolving character of European constitutional law.