Implementation of Brexit in the UK

Darren Harvey

LERU Brexit Seminar

LERU Brexit Seminar



In order to prepare the UK legal order for Brexit, the UK Government’s flagship piece of legislation, the EU Withdrawal Act 2018 (EUWA), received royal assent on 26th June 2018. The EUWA repeals the European Communities Act 1972 (ECA) on “exit day”, which is defined in section 20(1) EUWA as 29th March 2019 at 11pm (section 20(1)). Repealing the ECA will have two principal consequences. First, the mechanism through which EU law has effect in the UK’s dualist legal order will be removed (section 2(1) ECA). Second, the power to implement obligations arising from the UK’ membership of the EU in domestic law (e.g. transposing EU Directives) will be abolished (section 2(2) ECA). Without any further action, this would mean that vast swathes of EU law that currently applies in the UK by virtue of the ECA (e.g. EU Regulations, Directives, Decisions etc.) would cease to have effect domestically.

© 2016 UK Parliament/Jessica Taylor

The “Great Repeal Bill”: A Huge Exercise in Legislative Copying and Pasting

So as to prevent the inevitable legal vacuum that would arise from removing the domestic constitutional basis upon which EU law has effect in the United Kingdom, sections 2-4 EUWA converts (almost) all EU law currently in force in the UK into a freestanding body of domestic law. This is done through the creation of a new body of domestic UK law known as “retained EU law.”

According to the explanatory notes to the EUWA, “the principal purpose of the Act is to provide a functioning statute book on the day the UK leaves the EU. As a general rule, the same rules and laws will apply on the day after exit as on the day before.” Despite initially being referred to as the “Great Repeal Bill”, therefore, the EUWA as enacted represents “a huge, and imperative, exercise in legislative copying and pasting.”

The EUWA’s creation of this novel body of law has given rise to a number of complex issues that cannot be dealt with in detail here, including: the status of retained EU law within the domestic hierarchy of legal acts (e.g. primary or secondary legislation); the future of the principle of supremacy of EU law and how it operates in relation to retained EU law and the future legal relevance of post-Brexit CJEU case law. (For a good overview of many of these issue see the House of Commons Library Briefing Paper on the Status of Retained EU Law, available here)

Amending Retained EU Law: Disrupting the Constitutional Balance of Powers between Parliament and Government

Having retained this vast body of EU law via the EUWA, the next issue to be resolved is what to do with it moving forward? After all, much of the rationale for Brexit would be frustrated if the UK parliament opted to retain in perpetuity all those EU laws which applied in the UK at 10.59pm on 29th March 2019. While the UK is a member of the EU, the UK parliament is precluded from legislating in a manner that is incompatible with provisions of EU law. This ultimately stems from the principle that EU law is supreme over conflicting provisions of national law.

In contrast, a post-Brexit UK Parliament will no longer be under any obligation to comply with EU law, nor will EU laws adopted by the EU institutions after Brexit day have any effect in the UK. The fundamental difference between EU law during membership and retained EU law post-Brexit, therefore, is that the latter may be modified or revoked by acts of Parliament. What is more, in a number of instances the UK Government (along with the devolved authorities) will be able to legally alter retained EU law via secondary legislation.

In both cases, the EUWA makes provision for how different types of retained EU law may be subsequently amended by other acts of Parliament, secondary legislation or controversial Henry VIII clauses. Notably, section 8 EUWA enables ministers, by way of making regulations by statutory instruments, to prevent, remedy or mitigate: (a) any failure of retained EU law to operate effectively; or (b) any other deficiency in retained EU law, arising from the withdrawal of the UK from the EU. Furthermore, section 9 EUWA provides that a Minister may by regulations make such provision as they deem appropriate for the purposes of implementing a withdrawal agreement between the UK and EU.

Once again, the rules contained in the EUWA for determining which types of retained EU law may be amended by which types of legal acts, and the procedures according to which these amendments may be scrutinised, are complex and thus difficult to navigate. For the purposes of this short blog post, the take home message is that the EUWA envisages a considerable transfer of authority by Parliament to Government Ministers in order to deal with the complexities of Brexit.

The scope of these delegated powers gave rise to concerns during the EUWA’s passage through Parliament, with the House of Lords Constitution Committee noting that the “number, range and overlapping nature of the broad delegated powers would create what is, in effect, an unprecedented and extraordinary portmanteau of effectively unlimited powers upon which the Government could draw. They would fundamentally challenge the constitutional balance of powers between Parliament and Government and would represent a significant—and unacceptable—transfer of legal competence.”

Whilst there is no question that the delegation of certain powers is necessary in order to ensure that the UK legal order operates effectively as a result of Brexit, the extent of such powers in the EUWA nonetheless provides a further irony in a “Great Repeal” process that was instigated by a desire to restore the sovereignty of the UK Parliament.

The EUWA and Devolution: A Constitutional Crisis?

In addition to raising concerns about the division of powers between Parliament and the Executive, the EUWA has also given rise to a number of issues regarding the UK’s system of devolved law-making powers. The devolution of powers was agreed at a time when the UK was a member of the EU and the relevant Acts of Parliament reflect this state of affairs (Scotland Act 1998, Northern Ireland Act 1998 and Wales Act 2006.)

In Scotland, devolution operates on the basis of a reserved powers model, which provides that all areas of law not explicitly reserved to the Westminster Parliament in the Scotland Act 1998 fall within the competence of the Scottish Parliament. The default position, therefore, is that the Scottish Parliament has legislative competence in numerous policy fields including agriculture, the environment and fisheries.

For as long as the UK is a member of the EU, however, section 29(2)(d) of the Scotland Act 1998 provides that the Scottish Parliament cannot legislate in a manner contrary to EU law. Thus, the Scottish Parliament cannot at present legislate in a manner contrary to EU laws governing policy areas where it would ordinarily be competent under the devolution settlement.

Section 12 EUWA replaces the constraint upon the Scottish Parliament enshrined in section 29(2)(d) of the Scotland Act 1998 with a novel rule that an Act of the Scottish Parliament (ASP) cannot modify, or confer power by subordinate legislation to modify, retained EU law. Whereas the initial plan of the UK government was to prevent the Scottish Parliament from being able to modify any provision of retained EU law, the solution ultimately adopted in the EUWA is to preclude ASPs from modifying retained EU law as specified in regulations made by a UK Government Minister.

Consequently, in those areas specified by statutory instrument, the power to legislate will not return to the Scottish Parliament as initially envisaged under the devolution settlement, but shall remain outside the competence of the Scottish Parliament and therefore may only be amended by the UK Parliament or Government. This mechanism formed one of the principal reasons behind the Scottish Parliament’s decision to withhold its consent from the EU Withdrawal Bill (EUWB). According to constitutional convention, the UK Parliament will not normally legislate in areas of devolved powers or alter the scope of devolved competences without the agreement of the devolved legislatures.

By withholding its consent from the EUWB, the UK Parliament was faced with a choice: (i) remove the devolution provisions from the UK Withdrawal Bill; or (ii) ignore the position of the Scottish Parliament and legislate on devolution regardless of the lack of consent. In the end, the UK Parliament opted for option (ii), enacting the EUWA including Section 12 as described above into law.

Whilst there is no legal impediment to this course of action following the UK Supreme Court’s judgment in Miller that the scope and operation of constitutional conventions are not within the remit of the judiciary, the political implications of the UK Parliament’s course of action has given rise to discussion of a constitutional crisis. Indeed, some have drawn attention to the risk that undermining the Scottish devolution settlement may provide additional support for those seeking a second Scottish Independence Referendum.

But this is not the end of the story. In the event that option (i) was chosen (or simply that the EUWB did not make it through Parliament) this would have left Scots law unprepared for Brexit. Accordingly, the Scottish Parliament adopted the UK Withdrawal from the European Union (Legal Continuity) (Scotland) Bill. Subject to a few important exceptions, the Scottish Continuity Bill mirrors the EUWA by providing for the continuity of effect of EU law areas of devolved competence. It then confers powers upon Scottish Ministers to amend retained devolved EU law.

At the time of writing, the Scottish Continuity Bill is currently being contested by the UK government before the UK Supreme Court on the grounds that it is outside the competence of the Scottish Parliament. As a result, the Supreme Court will have an opportunity to rule on the limits of devolved competences and, in so doing, determine what a considerable portion of the post-Brexit legal landscape will look like.


In the run up to the UK’s referendum on EU membership, Boris Johnson claimed: “You cannot express the sovereignty of Parliament and accept the 1972 European Communities Act.” In repealing the European Communities Act, it seems to logically follow that, at least on Johnson’s definition, the EUWA restores the sovereignty of Parliament.

On closer inspection, however, the EUWA provides a somewhat more nuanced picture. As this short blog post has noted, the complexities of Brexit have resulted in legislative framework that provides: a massive copy and paste exercise that was initially billed as a great repeal, a purported taking back of parliamentary control that involves an unprecedented delegation of powers to the executive, and an approach to (re)asserting the supremacy of British law that may well have placed the very future of the United Kingdom itself into doubt.


Darren Harvey
University of Edinburgh

Darren Harvey is Early Career Fellow in EU Law at the University of Edinburgh and PhD Candidate in Law at the University of Cambridge. His research interests include in European Union law, comparative constitutional law and judicial review.

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