From Retained EU Law to Assimilated Law: A new perspective this New Year

As we enter the New Year, the legal landscape of the United Kingdom is undergoing a significant transformation. The UK domestic law that originated from EU obligations, known as “retained EU law”, is now being re-labelled as ‘assimilated law’ because of the Retained EU Law (Revocation and Reform) Act 2023 (“Retained EU Law Act”). This change reflects a shift in the domestic status and treatment of assimilated law, with the goal of progressing the domestication or assimilation of EU law in the UK.

Background

Retained EU law was created by the European Union (Withdrawal) Act 2018 (“Withdrawal Act”) following the end of the Brexit implementation period on 31 December 2020. It is made up of EU-derived domestic legislation, direct EU legislation, certain directly effective EU rights, powers, and duties and related EU and UK case law. The principle of supremacy governed, meaning that retained EU law was supreme over earlier legislation, but not over legislation passed after 31 December 2020.

Retained EU Law Act

The Retained EU Law Act is the second stage of government policy after the Withdrawal Act regarding EU law residue in the UK. The Retained EU Law Act: (1) revokes substantial amounts of Retained EU Law at the end of 2023; (2) re-labels retained EU law as ‘assimilated law’ from 2024; (3) changes the status and treatment of assimilated law; and (4) creates new powers to amend and restate assimilated law.

Non-supremacy of assimilated direct EU legislation

From 2024, the principle of supremacy of retained EU law will no longer apply in domestic UK law. This means that assimilated direct EU legislation must be read and given effect in a way that is compatible with all other domestic UK legislation. If there is a conflict, domestic UK legislation prevails over assimilated direct EU legislation. The Government can make regulations before the end of 23 June 2026 to re-impose the principle of supremacy in relation to a specific piece of assimilated direct EU legislation.

Non-supremacy of assimilated EU case law

The Supreme Court and Court of Appeal have previously been applying a test of whether it appeared “right to do so” when considering whether to depart from retained EU case law. From 2024, under the Retained EU Law Act, the Supreme Court and Court of Appeal must consider the following factors to decide whether to depart from retained EU case law: (1) foreign court decisions are not binding (unless otherwise provided); (2) relevant changes of circumstances to the assimilated EU case law; and (3) the extent that the assimilated EU case law restricts the proper development of domestic UK law.

There is also a new test that the Supreme Court and Court of Appeal may apply when considering whether to depart from assimilated UK domestic case law.

Powers to amend and restate assimilated law 

The Retained EU Law Act grants powers to amend assimilated law. It is now easier to amend assimilated direct legislation, and the Government have until 23 June 2026 to restate assimilated law that is not primary legislation or a provision in primary legislation inserted by secondary legislation. The Government must keep a dashboard showing the retained EU law and assimilated law (available here) up-to-date.

Comment

The New Year brings with it a new era of assimilated law in the UK. The transformation of retained EU law to assimilated law represents a significant change in the domestic status and treatment of what was once EU law, with the goal of progressing its domestication or assimilation in the UK, whilst creating the supremacy of UK law. As we move forward into 2024 and beyond, it will be interesting to see how these changes play out in the legal landscape of the United Kingdom. For more information, please get in touch.