The name by which retained EU law is known as regards all times after the end of 2023 (section 5(1), Retained EU Law (Revocation and Reform) Act 2023 (REUL Act)). Assimilated law comprises EU-derived domestic legislation and assimilated direct legislation (subject to various exceptions), together with the interpretations of it by the UK courts and any additions and modifications made to it by domestic law from time to time (section 6(7), European Union (Withdrawal) Act 2018 (EUWA)).

The renaming aimed to reflect the changes to the operation and interpretation of retained EU law after the end of 2023 made by sections 2, 3 and 4 of the REUL Act, which amended the EUWA (see Practice note, Retained EU Law (Revocation and Reform) Act 2023: Repeal of section 4 of the EUWA, Abolition of supremacy of EU law and Abolition of general principles of EU law).

After the end of 2023, retained EU law continues to be known as retained EU law as regards all times at or before the end of 2023 (section 5(2)). Sections 2, 3 and 4 of the REUL Act do not apply in relation to anything occurring before the end of 2023 (section 22(5)). The original EUWA provisions may still apply and may still be enforceable in legal proceedings that relate to acts or events which occurred before the end of 2023.

For more information, see Retained EU law and assimilated law FAQs: What is assimilated law?, Practice note, Retained EU Law (Revocation and Reform) Act 2023: Renaming of retained EU law and related law and Retained EU law toolkit.