Miller I [2017] / Miller II [2019] / GCHQ Case [1985] / Entick v Carrington [1765]
15 UK Landmark Constitutional Court Cases Guide 2026
Exhaustive analysis of 15 landmark UK constitutional cases: Miller I & II, GCHQ, Entick v Carrington, Pepper v Hart, AXA General Insurance, and Jackson v Attorney General.
Overview
UK constitutional law is shaped primarily by judicial decisions rather than a codified constitution. Key landmark cases include: Entick v Carrington [1765] EWHC KB J98 (state cannot enter property without lawful authority), GCHQ Case [1985] AC 374 (prerogative powers subject to judicial review), Pepper v Hart [1993] AC 593 (Hansard admissible to interpret legislation), Miller I [2017] UKSC 5 (Parliament must authorise triggering Article 50), Miller II [2019] UKSC 41 (prorogation of Parliament unlawful), and Factortame [1990] (EU law supremacy over Acts of Parliament).
Key Facts & Statutory Reference
| Item | Detail | Statutory / Official Source |
|---|---|---|
| Entick v Carrington [1765] | State cannot search/seize without legal authority | EWHC KB J98 — Rule of Law |
| GCHQ Case [1985] | Royal prerogative powers subject to judicial review | UKHL AC 374 |
| Pepper v Hart [1993] | Hansard admissible to resolve statutory ambiguity | UKHL AC 593 |
| Miller I [2017] | Parliament must authorise invoking Article 50 TFEU | UKSC 5 — Supreme Court |
| Miller II [2019] | Boris Johnson prorogation of Parliament unlawful | UKSC 41 — Supreme Court |
Frequently Asked Questions (FAQ)
The UKSC held by 8-3 that the Government could not use royal prerogative to trigger Article 50 (Brexit notification) without prior authorisation from Parliament. This led to the European Union (Notification of Withdrawal) Act 2017.
The House of Lords held that while the exercise of royal prerogative powers is exempt from parliamentary oversight, it is NOT immune from judicial review. This established that prerogative powers must be exercised reasonably, lawfully, and subject to judicial scrutiny.