Sources and institutions of EU law

The first week of EU Constitutional Law is not a mere institutional tour. It introduces the grammar of the legal order: where EU law comes from, who makes it, how legal authority is allocated, and why the Union cannot be analysed simply as an international organisation. For Durham first-year students, this topic sits at the junction of legal method, public law, and constitutional theory. The relevant questions are not only descriptive — what is a regulation, what does the Commission do, what is the Court of Justice? — but constitutional: how does a body created by treaties generate legal norms capable of binding states, institutions, companies, and individuals?

The EU legal order rests on treaties concluded by the Member States. Those treaties create institutions, confer competences, prescribe legislative procedures, and authorise secondary legislation. Yet the Court of Justice of the European Union has long insisted that the treaties are more than ordinary agreements between states. In Van Gend en Loos, the Court described the Community as a new legal order. In Costa v ENEL, it held that the law stemming from the treaty could not be overridden by domestic legal measures without undermining the basis of the Community. Those propositions are the foundation of later topics: direct effect, supremacy, preliminary references, EU fundamental rights, and the post-Brexit status of retained or assimilated EU law in the United Kingdom.

The basic source hierarchy is as follows. Primary law consists principally of the Treaty on European Union, the Treaty on the Functioning of the European Union, the Charter of Fundamental Rights, accession treaties, and general principles of EU law. Secondary law consists of regulations, directives, decisions, recommendations, and opinions, made under treaty powers. International agreements concluded by the Union form a further source. Soft law — communications, guidelines, notices, conclusions, and recommendations — lacks ordinary binding force but may structure discretion and expectations. Case law is indispensable because the Court of Justice has supplied much of the constitutional architecture: direct effect, supremacy, implied external competence, institutional balance, effective judicial protection, and the reviewability of institutional action.

Institutionally, the EU is not a state with a single sovereign legislature. It has a mixed constitution. The Commission promotes the Union interest and usually initiates legislation. The Council represents governments of the Member States. The European Parliament represents Union citizens. The European Council sets broad political direction. The Court of Justice ensures the interpretation and application of EU law. The European Central Bank and Court of Auditors have specialised constitutional roles. The resulting system is neither classical separation of powers nor pure diplomatic cooperation; it is a compound constitutional order in which legality, democracy, executive bargaining, and technocratic administration coexist.

For assessment purposes, treat this week as foundational. Do not learn a list of institutions mechanically. Ask four questions whenever confronted with an EU measure: first, what is the legal basis? secondly, which institution adopted it and by what procedure? thirdly, what legal form does it take? fourthly, what is its effect in EU and domestic law? Those questions will carry forward into nearly every Durham EU Constitutional Law problem and essay.

The European Union developed from post-war projects of economic reconstruction, political restraint, and legal integration. The European Coal and Steel Community was established in 1951, followed by the European Economic Community and Euratom in 1957. The original constitutional design was limited but ambitious: it placed strategically important economic sectors and the common market under institutions capable of producing binding legal rules. The legal technique was integration through law. Member States did not merely promise cooperation; they created institutions, conferred powers, and accepted judicial supervision.

The founding treaties were international treaties in formal origin, but the Court of Justice gradually constitutionalised them. The early cases transformed treaty obligations into enforceable legal rights and established that EU law could claim priority over conflicting national law. This development cannot be understood as judicial ornament. It was central to the common market. If each Member State could decide when treaty obligations mattered domestically, uniformity would be impossible. Direct effect made EU law usable by individuals. Supremacy secured its practical priority. Preliminary references connected national courts to the Court of Justice and produced a decentralised system of enforcement.

Institutional development followed enlargement and functional expansion. The Single European Act strengthened internal market law-making and extended qualified majority voting. Maastricht created the European Union, introduced Union citizenship, and constructed a pillar structure combining supranational and intergovernmental elements. Amsterdam and Nice adjusted institutions for enlargement. Lisbon abolished the pillar structure in most areas, gave legal personality to the Union, strengthened the ordinary legislative procedure, made the Charter legally binding, and consolidated the distinction between TEU and TFEU. The resulting Union remains based on conferral, but the fields of conferred competence are extensive.

The United Kingdom’s position adds a further historical layer. From accession in 1973 until withdrawal, EU law entered domestic law principally through the European Communities Act 1972. That Act was treated by UK courts as a constitutional statute and provided the domestic conduit through which directly effective EU law operated. Factortame illustrated the practical strength of that arrangement: an Act of Parliament could be disapplied where inconsistent with directly effective EU law. Brexit altered the domestic basis of EU law but did not make EU law irrelevant to legal education or practice. The European Union (Withdrawal) Act 2018 preserved large bodies of EU-derived and direct EU legislation as domestic law at the end of the implementation period. The Retained EU Law (Revocation and Reform) Act 2023 then altered the terminology and status of retained EU law, including the abolition of the domestic principle of supremacy after the end of 2023, subject to the statutory scheme.

For Durham first-year students, this history matters for two reasons. First, EU Constitutional Law is studied as public law: institutions and sources are constitutional structures, not administrative trivia. Secondly, the UK dimension is now bifurcated. You must understand EU law as it operates within the Union, and also the domestic afterlife of EU law after Brexit. Many weak answers collapse those questions. The Court of Justice’s doctrines remain central to understanding the EU legal order; the UK’s current domestic treatment of EU-derived law is a separate, statutory question.

1. Conferral. The Union acts only within competences conferred by the Member States in the treaties. This is the first principle of EU legality. Unlike a sovereign Parliament, the EU does not possess general legislative authority. A measure must be anchored in a legal basis, usually a treaty article identifying the field, objectives, procedure, and voting rule. Legal basis is therefore not a technical afterthought. It determines institutional participation, democratic legitimacy, and the scope of judicial review. A measure adopted on the wrong legal basis may be annulled.

1. Source hierarchy. EU law is arranged hierarchically. Primary law stands at the apex: the founding treaties, Charter rights, accession treaties, protocols, and general principles. Secondary legislation must comply with primary law. Regulations, directives, and decisions are binding legal acts; recommendations and opinions are not binding in the same way. International agreements concluded by the Union bind the institutions and Member States and can influence interpretation. Soft law may be legally significant without being formally binding. A good answer distinguishes bindingness, direct applicability, direct effect, and interpretative weight.

1. Institutional balance. EU institutions are not arranged according to a pure Westminster model. The Commission, Parliament, Council, European Council, Court of Justice, European Central Bank, and Court of Auditors each have treaty functions. The Court has treated respect for the institutional balance as a constitutional principle: one institution must not usurp the role assigned to another by the treaties. This principle matters in litigation over legal basis, delegation, comitology, agencies, and reviewability. It also explains why EU institutional law is not merely political science; it is enforceable constitutional law.

The landmark cases show how the Court of Justice turned treaty text into constitutional structure. Van Gend en Loos is the starting point. A customs dispute became the vehicle for a general theory: EU law may confer rights on individuals enforceable before national courts. The significance is not confined to direct effect. The case established that individuals, not only Member States and institutions, are subjects of the EU legal order. That proposition changed the enforcement model. Private litigants became agents of integration.

Costa v ENEL supplied the companion principle of supremacy. A domestic nationalisation measure conflicted with Community obligations. The Court reasoned that the treaty created an autonomous legal system, integrated into Member State legal systems, which national courts were bound to apply. If later domestic law could prevail at will, uniformity and reciprocity would collapse. Costa is often introduced as a supremacy case, but it is also a theory of legal order: the Union’s law is not merely externally binding international law.

Simmenthal developed supremacy operationally. A national court must give full effect to EU law and must not wait for a national constitutional court or legislature to remove the inconsistent provision. The practical importance is enormous. Supremacy is not only an abstract priority rule; it imposes duties on national courts deciding concrete disputes. It also illustrates the decentralised nature of EU judicial enforcement.

Les Verts is the canonical rule-of-law authority. The Court held that the Community is based on legality, so institutional measures must be open to review where they produce legal effects. The case helped constitutionalise judicial review at EU level. It also demonstrates that gaps in treaty drafting may be read in light of structural constitutional principles.

ERTA, often called AETR, introduced implied external competence. The Court held that where internal common rules have been adopted, Member States may be precluded from undertaking international commitments that affect those rules. The case matters for sources and institutions because it shows how competences are inferred from the scheme and effectiveness of treaty powers, not only from express words.

Meroni remains central to delegation. It restricts delegation of discretionary powers that would disturb the balance of powers established by the treaties. Its modern relevance appears in debates over EU agencies and technocratic governance. Even where administration becomes complex, institutional balance and legal accountability remain constitutional constraints.

Factortame belongs to the UK side of the story. The House of Lords accepted that domestic courts could grant interim relief and disapply inconsistent primary legislation where EU law required it. This was not because the UK Parliament had ceased to be sovereign in domestic constitutional theory, but because Parliament had enacted the European Communities Act 1972. The case is essential for understanding the pre-Brexit domestic reception of EU supremacy and why the post-Brexit statutory settlement matters.

See practice questions section below.

See further reading section below.