Case law plays a constitutive role in UK constitutional law, establishing and elaborating fundamental principles. The following decisions are foundational to understanding the nature and sources of the constitution.
Entick v Carrington (1765)
This case stands as an early and powerful statement of the rule of law and the limits of executive power. Secretary of State Lord Halifax issued a warrant authorising King's messengers to search Entick's premises and seize his papers. Entick sued in trespass. The Crown argued that executive necessity justified the search. Lord Camden CJ held that the warrant was unlawful: neither statute nor common law authorised it, and executive officers possessed no power to act without legal foundation. The case affirmed that state power must be grounded in law and that individuals possess residual liberty unless law provides otherwise.
Attorney General v Jonathan Cape Ltd [1976] QB 752
This case concerned the proposed publication of the diaries of Richard Crossman, a former cabinet minister. The Attorney General sought an injunction to restrain publication on the ground that it would breach the convention of collective cabinet responsibility. Lord Widgery CJ acknowledged that constitutional conventions exist and may inform legal obligations (for example, the law of confidence), but held that conventions themselves are not enforceable in court. The case clarified the boundary between law and convention, a distinction central to the UK's constitutional structure.
R v Secretary of State for the Home Department, ex parte Fire Brigades Union [1995] 2 AC 513
The Home Secretary announced that he would not bring into force a statutory scheme of criminal injuries compensation and would instead operate a less generous prerogative scheme. The House of Lords held, by a majority, that the minister's decision was unlawful. Once Parliament had legislated to create a statutory scheme, the prerogative power in the same field was displaced, and ministers were under a duty not to frustrate Parliament's intention. The decision illustrates the subordination of the prerogative to statute and the reviewability of prerogative decisions.
R (Jackson) v Attorney General [2005] UKHL 56
The Hunting Act 2004, which banned hunting wild mammals with dogs, was passed using the Parliament Act 1949 procedure without the consent of the House of Lords. Claimants challenged its validity, arguing that the 1949 Act itself was invalid because it had been enacted using the 1911 Act's procedure. The House of Lords unanimously rejected the challenge, holding that the 1911 Act had redefined Parliament for certain purposes and that the 1949 Act was validly enacted. Obiter remarks are significant. Lord Steyn suggested that parliamentary sovereignty is a construct of the common law, and that in extreme circumstances—such as an attempt to abolish judicial review or subvert the democratic basis of the constitution—courts might decline to apply an Act of Parliament. Lord Hope spoke of the supremacy of Parliament being a creation of the common law. These dicta have fuelled academic debate over whether parliamentary sovereignty is absolute or subject to fundamental common law limits.
R (Miller) v Secretary of State for Exiting the European Union [2017] UKSC 5 (Miller I)
The government argued that ministers could trigger Article 50 TEU, initiating the UK's withdrawal from the EU, by prerogative power. The Supreme Court held, by a majority of 8–3, that an Act of Parliament was required. The European Communities Act 1972 had conferred EU law rights on individuals; these rights could not be removed by executive action alone. The prerogative cannot be used to alter domestic law. The decision reaffirmed parliamentary sovereignty and the principle that rights conferred by statute may be withdrawn only by statute. The Court also held that the Sewel Convention, though politically significant, was non-justiciable.
R (Miller) v Prime Minister; Cherry v Advocate General for Scotland [2019] UKSC 41 (Miller II)
In September 2019, the Prime Minister advised the Queen to prorogue Parliament for five weeks during the critical period before the UK's scheduled withdrawal from the EU. The Supreme Court unanimously held the prorogation unlawful. The Court identified two fundamental constitutional principles: parliamentary sovereignty and parliamentary accountability of the executive. Prorogation is a prerogative power, but it is justiciable when its exercise prevents Parliament from performing its functions. The length and timing of this prorogation had the effect of frustrating Parliament's ability to scrutinise the executive. The advice to prorogue was unlawful, and the prorogation was void. The decision represents an assertion of judicial authority to review prerogative acts affecting the core functions of Parliament and is among the most significant constitutional cases in modern times.
AXA General Insurance Ltd v Lord Advocate [2011] UKSC 46
This case concerned a challenge to an Act of the Scottish Parliament abolishing the right to damages for pleural plaques. The Supreme Court held that Acts of the Scottish Parliament, though primary legislation for the purposes of the Human Rights Act, are subordinate legislation from a UK constitutional perspective and are subject to judicial review for compatibility with retained EU law, ECHR rights, and the scope of devolved competence. Obiter dicta addressed whether an Act of the UK Parliament could be reviewed for irrationality or violation of the rule of law. Lord Hope doubted that the UK Parliament could be reviewed on substantive grounds; Lord Reed suggested that an extreme and wholly arbitrary statute might be vulnerable, though such a case is unlikely ever to arise. The case reflects ongoing judicial consideration of the limits, if any, on parliamentary sovereignty.