Introduction
The relationship between English law and European Union (EU) law has been one of the most significant and debated topics in UK constitutional law for the past fifty years. It is a relationship that has evolved dramatically, moving from complete separation to deep integration, and now to a new and complex phase of disengagement following the UK’s withdrawal from the EU. This essay will explain this changing relationship by examining three distinct periods: the time before the UK’s accession, the period of membership from 1973 to 2020, and the current post-Brexit legal landscape. It will argue that while the formal supremacy of EU law has ended, its legacy continues to shape English law in a profound, albeit diminishing, way.
Before UK Membership: Parliamentary Sovereignty and Dualism
Before the UK joined the European Economic Community (EEC) in 1973, the legal relationship was simple: English law and EEC law were two separate and independent systems. The foundational principle of the UK constitution was, and arguably still is, the doctrine of parliamentary sovereignty. As articulated by the constitutional theorist A.V. Dicey, this principle traditionally means that Parliament has the power to make or unmake any law whatsoever, and no other body has the right to override or set aside an Act of Parliament (Dicey, 1915).
Furthermore, the UK operates a 'dualist' system in its approach to international law. This means that international treaties signed by the government do not automatically become part of domestic law. For an international treaty to have legal effect within the UK, an Act of Parliament must be passed to incorporate its provisions into the domestic legal system. Therefore, before 1973, the treaties establishing the EEC had no direct legal standing in English courts. The relationship was one of two sovereign legal orders existing in parallel, with no formal overlap.
UK Membership (1973-2020): The Ascendancy of EU Law
The UK's entry into the EEC fundamentally altered this position. Membership required accepting the entire body of EU law, including the core principles of supremacy and direct effect, which were incompatible with the traditional understanding of parliamentary sovereignty. The mechanism for this constitutional revolution was the European Communities Act 1972 (ECA 1972).
The ECA 1972 acted as a 'conduit pipe' through which EU law flowed into the UK legal system. Section 2(1) of the Act gave legal effect to EU laws that were 'directly effective', meaning they could be relied upon by individuals in UK courts without any further Act of Parliament. This included EU Regulations and certain Treaty Articles and Directives.
More radically, section 2(4) of the ECA 1972 required that any UK legislation, whether passed before or after the Act, was to be interpreted and have effect subject to the requirements of EU law. This provision directly addressed the core principle of EU law: its supremacy. The principle of supremacy was established by the European Court of Justice (ECJ), now the Court of Justice of the European Union (CJEU), in the landmark case of Costa v ENEL (1964). The ECJ ruled that by creating the Community, member states had limited their sovereign rights and that Community law would take precedence over any conflicting provision of national law.
For many years, UK courts grappled with this new hierarchy. The turning point came in the case of R v Secretary of State for Transport, ex parte Factortame Ltd (No 2) [1991]. Spanish fishing boat owners claimed that the UK’s Merchant Shipping Act 1988 discriminated against them in a way that breached EU law. The House of Lords, the highest UK court at the time, asked the ECJ if it had the power to temporarily suspend the application of an Act of Parliament pending a final ruling. The ECJ confirmed it did. Consequently, the House of Lords granted an injunction that effectively suspended parts of the Merchant Shipping Act 1988. This was a clear and dramatic demonstration that, through the ECA 1972, Parliament had voluntarily accepted that UK courts had a duty to set aside a national statute if it conflicted with EU law. During this period, English law was subordinate to EU law in areas where the EU had competence.
After Brexit: A New Legal Order
The UK's withdrawal from the EU on 31 January 2020 triggered another fundamental change in the relationship. The European Union (Withdrawal) Act 2018 (EUWA 2018) was enacted to manage the legal transition and is the key statute governing the post-Brexit relationship.
The primary function of the EUWA 2018 was to repeal the ECA 1972 on 'exit day', thereby cutting off the flow of new EU law into the UK legal system. However, to avoid a huge gap in the UK statute book, section 2 of the EUWA 2018 created a new category of domestic law called 'retained EU law' (REUL). This process essentially took a snapshot of EU law as it applied to the UK on exit day and converted it into UK domestic law. REUL included EU regulations, decisions, and rights that were directly applicable in the UK before exit day.
Crucially, the EUWA 2018 also reversed the legal hierarchy established by the ECA 1972. Section 5 states that the principle of the supremacy of EU law does not apply to any law made by the UK Parliament on or after exit day. This restored the traditional principle that a newer Act of Parliament can override an older one. However, for a transitional period, retained EU law continued to have a special, supreme status over laws made before exit day.
The status of judgments from the CJEU also changed. Under the EUWA 2018, pre-exit case law from the CJEU continues to have the same binding or persuasive authority as it did before. However, the UK Supreme Court and the Court of Appeal were given the power to depart from retained CJEU case law.
The relationship has continued to evolve. The Retained EU Law (Revocation and Reform) Act 2023 has taken the process of legal separation further. This Act renamed 'retained EU law' as 'assimilated law' to reflect its new status as a permanent feature of the domestic legal system, rather than a temporary legacy. More significantly, it ended the principle of the supremacy of retained EU law over other domestic law from the end of 2023 (Craig, 2023). This means that the special status of the law inherited from the EU has now been largely removed, and it can be treated more like any other domestic law, which can be changed or repealed by Parliament.
Conclusion
In conclusion, the relationship between English law and EU law has been a journey from separation to integration and back towards divergence. Initially, under the doctrine of parliamentary sovereignty, English law was entirely separate. Membership of the EU, facilitated by the ECA 1972, required the acceptance of EU law's supremacy, a principle confirmed dramatically by the courts in cases like Factortame. This period saw English law become subordinate to EU law in many areas of policy. With Brexit, this relationship has been fundamentally reset. The EUWA 2018 repealed the ECA 1972 and ended the general principle of EU law supremacy. While a large body of EU law has been preserved as 'assimilated law' to ensure legal continuity, its special status has been progressively dismantled by the UK Parliament, most recently by the 2023 Act. The formal relationship of subordination is over, but the legacy of forty-seven years of membership means that the substance of EU law continues to be an important, though now entirely domestic, source of English law.
References
Craig, P. (2023) 'The Retained EU Law (Revocation and Reform) Act 2023: A Constitutional Mess and a Constitutional Outrage', U.K. Const. L. Blog, 2 July. Available at: [https://ukconstitutionallaw.org/2023/07/02/paul-craig-the-retained-eu-law-revocation-and-reform-act-2023-a-constitutional-mess-and-a-constitutional-outrage/](https://ukconstitutionallaw.org/2023/07/02/paul-craig-the-retained-eu-law-revocation-and-reform-act-2023-a-constitutional-mess-and-a-constitutional-outrage/) (Accessed: 15 October 2023).
Costa v ENEL (Case 6/64) [1964] ECR 585.
Dicey, A.V. (1915) Introduction to the Study of the Law of the Constitution. 8th edn. London: Macmillan.
European Communities Act 1972. c. 68.
European Union (Withdrawal) Act 2018. c. 16.
R v Secretary of State for Transport, ex parte Factortame Ltd (No 2) [1991] 1 AC 603.
Retained EU Law (Revocation and Reform) Act 2023. c. 28.
Van Gend en Loos v Nederlandse Administratie der Belastingen (Case 26/62) [1963] ECR 1.
