Retained EU Law: Introduction


1         Introduction

Before Brexit, EU law took effect under the European Communities Act 1972 either by means of direct effect under s2(1) or were given effect by means of regulations made under s2(2).

The European Union (Withdrawal) Act 2018 provided the means of avoiding the legal vacuum that would otherwise have arisen once EU law ceased to be applicable in Great Britain. This would have occurred on exit day, 31 January 2020, on the repeal of the 1972 Act and when the UK ceased to be a Member State of the EU.

The European Union (Withdrawal Agreement) Act 2020 amended the 2018 Act to accommodate the implementation period following 31 January 2020 until 31 December 2020[1] (the 2018 Act made no such provision) and contains substantive provisions to give effect to the Withdrawal Agreement.

The UK left the EU on 31 January 2020, exit day, and since that date has no longer been a Member State.

The intention underlying the creation of retained EU law was that “… legal rights and obligations in the UK should where possible be the same after we have left the EU as they were immediately before we left.”[2]

Furthermore, any question as to the meaning of retained EU law is to be determined in the courts in Great Britain with reference to EU case law as it stood immediately before the UK left the EU.[3]

An approach designed and intended to preserve legal certainty.


2          Implementation Period

During the implementation period, UK law continued to follow EU law which took precedence over UK law under the terms of the Withdrawal Agreement, not the EU treaties and the 1972 Act which was repealed on exit day.

The jurisdiction of the Court of Justice remained unchanged during the implementation period.

The implementation period was capable of a single extension by mutual agreement reached before 30 June 2020 for up to two years, although the 2020 Act precluded such a step being taken (so would have required to be amended) and no extension was sought or secured.

At 11.00 pm on 31 December 2020, IP completion day, a snapshot of all EU law which then applied to the UK was taken and incorporated into UK domestic law for continuity and to preserve legal certainty. This now forms a body of law known as ‘retained EU law’.

EU law in force which applied before IP completion day, and which required action to be taken after completion day still apply as a matter of domestic law.

Decisions of the Court of Justice prior to IP completion day form a body of law known as ‘retained EU case law’.

After IP completion day, on 1 January 2021, Great Britain became a ‘third country’ in the eyes of the EU.

Retained EU law will remain in force unless and until it is amended or repealed.

The inclusion of so much discussion about EU law has been undertaken because:

It is impossible to understand how retained EU law operates without an understanding of its EU law origins and of how EU law was given effect in the UK during EU membership.[4]

Northern Ireland (NI), for almost all practical purposes, remains in the EU and NI will continue to apply EU single market rules for goods and remain aligned to EU rules on customs and VAT.


3          Interpreting the Law

The National Archives hosts almost 160,000 legislative provisions that originate from the EU dating back to 1953 and which include retained EU law.

Many provisions of retained EU law refer to institutions, bodies and processes in which the UK no longer participates. It was therefore necessary to make amendments to retained EU law in order that they may function and ensure their operability can be maintained.

Defra has indicated that there are about 850 retained EU legislative measures within its area of responsibility that are subject to around 100 domestic regulations intended to maintain their operability.

In the future UK law must be interpreted in accordance with retained EU law as it stood on 31 December 2020, as amended by relevant domestic operability and other regulations and any relevant retained EU case law. The National Archives undertook the task of capturing legislation originating from the EU which is available on and includes retained EU law.

A key feature of EU law as it has been applied in the past is the principle of supremacy of EU law. Where there was any conflict between domestic law and EU law the latter prevailed, and the former was set aside. The principle of the supremacy of EU law is preserved so that it continues to apply on or after IP completion day so far as relevant to the interpretation of any enactment or rule of law passed or made before IP completion day.[5] The preservation of the principle of supremacy is to ensure consistent interpretation of retained EU law.

The principle of the supremacy of EU law does not, however, apply to any enactment or rule of law passed or made on or after IP completion day.[6]

The future development of EU law may, or may not, have some influence on future UK law, depending on the extent to which the UK seeks to be aligned with EU law in the years to come. EUR-Lex is a primary source of EU law.

Retained EU law is a new and novel concept, it remains to be seen how it develops in the future. In order to understand and interpret retained EU law, it is essential to have an understanding of EU law and how it worked when the UK was a member of the EU.

[1] The legislation uses the term ‘implementation period’ but this carries the same meaning as ‘transition period’ which appears in the Withdrawal Agreement and was more commonly used.

[2] Department for Exiting the European Union, Legislating for the United Kingdom’s withdrawal from the European Union (White Paper, Cm 9445, 2017), p14

[3] European Union (Withdrawal) Act 2018, s6

[4] Duhs E and Rao I, Retained EU Law: A Practical Guide, The Law Society, 2021, p3

[5] Op. cit., s5

[6] Op. cit., s5(1)