Treaty on European Union

The Treaty on European Union (‘TEU’) finds its origins in the Treaty of Maastricht, which came into effect on 1 November 1993. Almost a decade previous, however, steps had already been taken to produce a draft treaty^[1] which proposed a ‘fully federal Europe with common foreign, macro-economic and trade policies and a devolved system of central institutions.’^[2] Damian Chalmers et al. identify a number of political influences driving this movement. Firstly, it is suggested that recession in the 1980s prompted national governments to consider further European integration as a potential solution to reinvigorating economies. Furthermore, lobby groups had congregated in Brussels since the 1970s which were ‘increasingly rallying for European solutions.’^[3] Meanwhile, the European Parliament had become more assertive. It adopted the draft in 1984, following work led by Altiero Spinelli as coordinating rapporteur of its Committee on Institutional Affairs.^[4]

In 1989 the European Council endorsed a three-stage approach to economic and monetary union and agreed that the first stage would begin in July 1990^[5]. It was believed by some that monetary union would ‘not be sustainable without further political integration’^[6]. Intergovernmental conferences on monetary and political union led to the Maastricht Treaty, which established the European Union (EU)^[7]. Article A of the original treaty, now Article 1 TEU, described it as a new stage in creating ‘an ever closer union among the peoples of Europe’^[8]. Economic and monetary union and closer political integration were both central to the treaty.

Title I of the current TEU sets out the EU’s values in Article 2 and the principles of conferral, subsidiarity and proportionality in Article 5. Article 6 recognises the Charter of Fundamental Rights of the European Union as having the same legal value as the Treaties^[9]. Title II sets out democratic principles, including representation of citizens in the European Parliament and the contribution of national parliaments. Title III sets out the institutional framework. Title IV concerns enhanced cooperation between Member States and Title V governs the EU’s external action and common foreign and security policy. Title VI includes legal personality (Article 47), treaty revision (Article 48), accession (Article 49) and withdrawal (Article 50).

Maastricht established what became known as the EU’s three pillars: the European Communities, the common foreign and security policy, and cooperation in justice and home affairs. As early as 1993, an editorial in the European Law Review warned of a ‘multi-speed Europe’^[10] and drew attention to the differing reach of judicial control^[11]. The Treaty of Lisbon removed the pillar structure, while retaining special rules for the common foreign and security policy. Articles 24 TEU and 275 TFEU limit the Court of Justice’s jurisdiction in this area. In KS and KD v Council (Joined Cases C‑29/22 P and C‑44/22 P), the Court confirmed that the limits do not extend to acts and omissions unrelated to political or strategic choices in that policy area.

The Treaty on the Functioning of the European Union

If the TEU provides the broad legal basis for the EU and its institutions, the Treaty on the Functioning of the European Union^[12] (TFEU) sets out the Union’s competences and more detailed procedures^[13]. It originated in the 1957 Treaty of Rome establishing the European Economic Community. The Lisbon Treaty amended and renamed what had by then become the Treaty establishing the European Community. The Treaty establishing a Constitution for Europe, signed in 2004, failed to enter into force after voters in France and the Netherlands rejected it in 2005. Damian Chalmers et al. identify several factors behind the constitutional project^[14], including the desire for a bill of rights and institutional reform to allow the Union to function efficiently after enlargement^[15]. The Charter had been proclaimed in 2000 and acquired binding force under Lisbon.

As the title suggests, the TFEU provides the detailed legal framework under which the EU operates. Part One sets out categories and areas of EU competence. Part Two concerns non-discrimination and EU citizenship. Part Three includes the internal market and free movement of goods, and Part Six sets out the procedures by which the EU makes legislation. As Paul Craig notes, the accelerated agreement on the text in October 2007 was justified by its similarity to the proposed Constitutional Treaty in important respects^[16]. The Member States signed the Lisbon Treaty on 13 December 2007.

Article 288 TFEU provides that EU regulations are binding in their entirety and directly applicable in Member States. Directives bind the Member States to which they are addressed as to the result, leaving national authorities the choice of form and methods. A sufficiently clear, precise and unconditional provision of a directive may be relied on against the state or an emanation of the state after the implementation deadline has passed if the directive has not been properly implemented. Van Duyn v Home Office illustrates this principle^[17]. A directive cannot of itself impose an obligation on a private party, as Marshall (Case 152/84) confirmed. Article 288 also provides that decisions are binding in their entirety, subject to any specified addressees, and that recommendations and opinions have no binding force.

A study published in 2004 found that regulations accounted for about 31% of the EU legal instruments it examined^[18].

2026 update

The Treaty on European Union and the TFEU remain the EU’s foundational treaties. The United Kingdom left the EU on 31 January 2020 under Article 50 TEU, and the transition period ended on 31 December 2020. The UK–EU relationship is now governed in large part by the Withdrawal Agreement and the Trade and Cooperation Agreement. Section 7A of the European Union (Withdrawal) Act 2018 gives domestic effect to relevant rights and obligations under the Withdrawal Agreement, including those under the Windsor Framework for Northern Ireland.

The European Union (Withdrawal) Act 2018 preserved specified EU-derived legislation and incorporated specified directly applicable EU legislation into UK law at the end of the transition period. From 1 January 2024, the surviving body of retained EU law was renamed assimilated law under the Retained EU Law (Revocation and Reform) Act 2023. That Act also repealed the general saving of directly effective rights under section 4 of the 2018 Act, subject to specific savings. The Withdrawal Agreement continues to operate under its separate statutory framework.

The Court of Justice continues to apply both treaties together. In Commission v Malta (Case C‑181/23), it held that Malta’s 2020 investor citizenship scheme infringed the EU citizenship provision in Article 20 TFEU and the duty of sincere cooperation in Article 4(3) TEU.

Last updated: 12 November 2026

Bibliography

Consolidated version of the Treaty on European Union [2008] OJ C115/13

Consolidated Version of the Treaty on the Functioning of the European Union [2008] OJ C115/47

Case 41/74 Van Duyn v Home Office [1974] ECR 1337

von Bogdandy, A., et al., ‘Legal Instruments in European Union Law and their Reform: a Systematic Approach on an Empirical Basis’ (2004) 23(1) Yearbook of European Law 91

Chalmers, D., et al., European Union Law (2^nd ed., Cambridge University Press 2010)

Craig, P., ‘The Treaty of Lisbon, process, architecture and substance’, (2008) 33(2) European Law Review 137

Editorial, ‘The Treaty on European Union enters into force’, (1993) 18(6) European Law Review 473

European Council, Bulletin of the European Communities, No. 6-1989

European Parliament, ‘Draft Treaty Establishing the European Union’ [1984] Official Journal C77/33