Retained/assimilated EU law post-Brexit

LS.09 — Retained / Assimilated EU Law Post-Brexit

The framework

At the end of the transition period (31 Dec 2020), the European Union (Withdrawal) Act 2018 (EUWA) snapshotted most EU law into domestic law as retained EU law, made up of three streams:

• EU-derived domestic legislation (EUWA s.2) — UK secondary legislation already made under the European Communities Act 1972.
• Direct EU legislation (EUWA s.3) — EU regulations converted directly into domestic law.
• Retained general principles and rights (EUWA s.4) — directly effective Treaty rights etc.

The REUL Act 2023 changes (know these)

• Renamed retained EU law to "assimilated law" from 1 January 2024.
• Ended the supremacy of EU law from end of 2023 — assimilated law no longer overrides later inconsistent domestic statutes.
• A "sunset" originally threatened to revoke much REUL automatically; this was replaced by a named schedule of revocations, so most assimilated law survives.

The departure test (the key trap)

• REUL Act 2023 s.6 would have introduced a new statutory departure test plus a lower-court reference procedure — but it never came into force (commencement was revoked by SI 2024/976). Do not apply it.
• The governing rule remains EUWA 2018 s.6. The Supreme Court may depart from assimilated EU case law, applying the same test it uses to depart from its own decisions (s.6(5)). The Court of Appeal and the other relevant courts designated by the 2020 Relevant Court Regulations may also depart, applying the same test the Supreme Court would apply (reg 5), not the Court of Appeal's narrower test for departing from its own decisions. They remain bound so far as post-transition domestic case law that is binding on them has modified or applied the EU case law (reg 4(2)).
• Lower courts and tribunals remain bound by assimilated EU case law unless and until a senior court departs.

Interpretation

• Pre-exit CJEU judgments are binding unless departed from as above; post-exit CJEU judgments are not binding but may be considered (EUWA s.6(2)).
• Courts interpret assimilated law in line with retained case law and general principles as modified by later domestic statute.

Common SBAQ traps

• "Retained EU law" = the term up to end 2023; "assimilated law" from 1 Jan 2024. Use the right label for the date.
• Supremacy ended at end of 2023 — don't say EU law still trumps later UK Acts.
• REUL Act s.6 is a non-starter — answers relying on its "new test" or lower-court reference route are wrong; the EUWA s.6 framework still governs.
• Only senior courts can depart; first-instance judges cannot.

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