Brexit ten years on: the law

To mark the ten year anniversary of the EU referendum on 23 June, UK in a Changing Europe experts have written a short series of blogs reflecting on some of the issues at the heart of Brexit then and now. Here, Catherine Barnard reflects on the legal implications of Brexit.

One of the most common questions asked post-Brexit is: has the law changed much? In the run up to the referendum, Brexiters had made a big play on taking back control of our laws. This was reiterated in the government’s 2018 Command Paper: ‘EU law in the UK will end, as will the jurisdiction of the Court of Justice of the European Union (CJEU).’ It continued, ‘The laws that we live by will once again be passed by our elected representatives in Belfast, Cardiff, Edinburgh and London – who are fully accountable to the people of the UK. UK courts will no longer refer cases to the CJEU, with our Supreme Court truly supreme.’

Has this happened? The answer is yes – and no.

Let’s start with the adoption of new, post-Brexit laws. It is certainly the case that, post-Brexit, the UK has had the freedom to legislate for itself. However, that freedom to develop new UK rules has been constrained by four factors.

First, a lack of clarity as to what a new, independent UK regime might look like, not least because there was so little planning done before Brexit. Financial services were seen as an obvious contender for reform. The cap on bankers’ bonuses, introduced after the 2008 financial crisis, has been removed. However, the scale of divergence on financial services has been less than anticipated, given it was identified by the Chancellor in 2022 as a priority sector for regulatory reform.

Second, there has been a question of civil service/government and legislative capacity. With so much energy devoted to preparing for a no-deal Brexit, then delivering Brexit itself, and then Covid, there has been little time to develop an independent UK regulatory regime.

Third, some areas, like environmental protection and workers’ rights, are subject to the so-called ‘level playing field’ provisions in the Trade and Cooperation Agreement (TCA), which forbid either side from reneging on 2020 levels of protection and the UK from failing to broadly keep up with new EU rules. Significant divergence from EU rules (leading to weaker standards) in these areas would eventually lead to tariffs.

Fourth, to protect the Good Friday Agreement, the Northern Ireland Protocol (NIP)/Windsor Framework (WF) requires Northern Ireland to dynamically align (i.e. keep up to date) with about 300 EU rules. The greater the regulatory divergence by the other UK nations, the ‘harder’ the GB/NI border would become, meaning that more checks would take place, creating more disruption to the movement of goods. More generally, manufacturers did not want regulatory divergence from EU rules, since this would increase their costs in respect of GB/NI and GB/EU trade. The devolved administrations were not keen to depart either.

What about pre-existing EU law? Some hoped that Brexit would mean the wholesale repeal of EU law on the UK statute book. However, there was no new UK regulatory regime for matters as diverse as airline safety, food safety and workers’ rights. Continuity, and not repeal, was therefore the order of the day. This was delivered by the EU (Withdrawal) Act 2018 which took a snapshot of all EU legislation on the UK statute book and ensured it continued after Brexit. Some legislation, such as the rules on free movement, was turned off because it was no longer suitable in the post-Brexit world. Other legislation was amended to remove, for example, references to the European Commission and to replace them with UK equivalent bodies.

But that still left a huge swathe of EU-derived legislation, known as retained EU law (REUL). The problem was: no one knew how much. Originally it was thought to be about 2,500 pieces yet, as of early 2026, that number had grown to almost 7,000. Jacob Rees Mogg MP wanted a ‘bonfire of EU rules to power Brexit innovations’, which he aimed to deliver via the Retained EU Law (Revocation and Reform) Bill. A change of Prime Minister (Rishi Sunak) put a stop to such wholesale ‘arson’ but did ensure that the concept of supremacy of EU law (i.e. EU law taking precedence over conflicting national law) was removed from the UK statute book. Retained EU law was renamed as assimilated law.

Since Rishi Sunak’s time as Prime Minister, enthusiasm from government for regulatory divergence has waned, largely because of pressure from business, to the extent that now the (Labour) government’s position is that divergence should be ‘the exception, not the norm’. And if future agreements with the EU are signed, on matters such as SPS (sanitary and phytosanitary standards) and emissions trading, these will also require not just catching up with the EU rules which have been adopted since Brexit but also staying up to date with new rules. And this will mean the government having to take the power to implement EU rules by secondary, not primary, legislation – providing only a minimal scrutiny role for MPs.

And what about the role of the European Court of Justice (CJEU). Finished? Not so fast. Pre-Brexit case law continues to bind UK courts unless the Supreme Court or the Court of Appeal decides otherwise. They have been reluctant to do so. Even post-Brexit EU case law should be taken into account by the UK courts when interpreting a provision of assimilated law. References (i.e. questions) to the CJEU have largely been stopped except in respect of matters under the NIP/WF and the citizens’ rights element of the Withdrawal Agreement (until 2028). The CJEU also has a say on the interpretation of concepts of EU law which arise in the context of any disputes under the Withdrawal Agreement which goes to arbitration. A question must be referred to the CJEU although it is the arbitration panel which makes the final decision. A similar mechanism is likely to be provided for under any future UK-EU agreement on, for example, SPS or emissions trading. Under the TCA, which is a free trade agreement under international law, the CJEU has no role to play. But even here, in the first and only UK-EU dispute – on sand eels – the parties and interveners referred to concepts of EU law in their arguments.

EU law may have formally gone in Great Britain, but it is far from forgotten. Future agreements with the EU mean more EU law, not less, and the CJEU will continue to have a residual role.

By Catherine Barnard, Senior Fellow, UK in a Changing Europe & Professor of EU Law and Employment Law, University of Cambridge.