The Constitution Is Not a Blank Cheque: Five Misreadings Westminster Should Retire

Westminster has never lacked confidence in its own constitutional opinions. It has often lacked precision. In 2026, as another heavy legislative session tests the relationships between Parliament, ministers and the courts, the quality of public argument matters more than ever. A constitution that relies on statute, common law and convention cannot afford lazy shorthand. Five misreadings recur with particular regularity.

Sovereignty is not a doctrine of executive immunity

The first myth is that parliamentary sovereignty means the courts cannot review anything done in Parliament's name. Sovereignty means that Parliament can make or unmake any law, and that the courts will not invalidate an Act of Parliament. It does not mean that ministers may act however they please. Judicial review of executive action is not a challenge to sovereignty; it is the enforcement of legality within the framework Parliament has created.

The distinction is not academic. Courts have long construed ouster clauses narrowly, from Anisminic v Foreign Compensation Commission in 1969 to R (Privacy International) v Investigatory Powers Tribunal in 2019. They do not do so because they claim superiority over Parliament, but because Parliament is presumed not to have authorised unlawful action. The same logic applies to statutory instruments: a minister may exercise only the powers the parent Act confers. In the 2026 session, as bills continue to seek broad discretionary powers and tighter limits on challenge, that distinction will be tested again.

The Crown is ceremonial in form, not in law

The second myth is that the monarchy has no real power. In personal terms, the monarch acts on ministerial advice and the reserve powers are tightly constrained by convention. In legal terms, however, the Crown remains the source of much executive authority. Prerogative powers—over foreign affairs, appointments, passports and armed forces deployment, among others—are exercised by ministers in the Crown's name. They are real powers, even when their exercise is politically accountable.

The Supreme Court's judgment in R (Miller) v Secretary of State for Exiting the European Union in 2017 turned on exactly this point: prerogative power could not be used to achieve what statute had reserved to Parliament. The lesson is not that the monarchy governs. It is that the executive's legal toolkit is inherited from the Crown and deserves examination. Reformers who want to codify or constrain prerogative powers should do so openly. Pretending the powers are decorative leaves them unexamined.

An uncodified constitution is still a constitution

The third myth is that the United Kingdom has an unwritten constitution. It is uncodified, not unwritten. The Bill of Rights 1689, the Parliament Acts, the Scotland Act 1998, the Human Rights Act 1998, the European Union (Withdrawal) Act 2018 and successive devolution and elections statutes are all written law. So too are the common-law principles that courts apply, including the recognition of constitutional statutes in Thoburn v Sunderland City Council in 2002.

What the UK lacks is a single consolidated document with a special amendment procedure. That is a difference of form, not of substance. The absence of a codified text does not mean the absence of rules. It means the rules are dispersed, sometimes ambiguous and often dependent on political restraint. The 2026 argument for publishing a constitutional rulebook is worthwhile precisely because so much is already written but scattered. Codification is a design choice, not a leap from nothing into something.

Conventions bind politics before they bind courts

The fourth myth is that conventions are unenforceable, and therefore irrelevant. Conventions are not generally enforced by courts, but they are not mere habits. They are binding political rules that allocate power and structure behaviour: ministerial responsibility, collective Cabinet responsibility, royal assent, the Sewel convention and the expectation that governments will accept adverse votes on confidence.

The Supreme Court in Miller in 2017 treated the Sewel convention as political rather than legal. That did not make it meaningless. It meant that its enforcement lay with politics, not litigation. In a year when norms are under strain, breach of convention is a constitutional event, not a technical slip. Conservative constitutionalism has always understood that formal legal rules depend on a wider ecology of restraint. Ignoring conventions because judges will not police them is like ignoring a fence because it is not a wall.

The Human Rights Act does not license judicial repeal

The fifth myth is that the Human Rights Act allows judges to strike down Acts of Parliament. It does not. Section 3 requires courts to read legislation compatibly with Convention rights so far as it is possible to do so. Section 4 allows a declaration of incompatibility where it is not. Such a declaration does not change the law or invalidate the statute. It invites Parliament to respond.

That is a meaningful transfer of interpretive authority, and conservatives are entitled to argue for reform. But the case should rest on accurate description. Courts cannot repeal statutes under the Act; they can identify a conflict and leave the political remedy with the legislature. In 2026, with the Act's operation under renewed scrutiny, precision about what it actually does is the minimum required of anyone proposing to change it.

The common thread in these five misreadings is a desire for simplicity. Sovereignty becomes executive immunity; the Crown becomes a pageant; the uncodified constitution becomes a void; conventions become etiquette; the Human Rights Act becomes judicial supremacy. Each simplification makes debate easier and law-making worse. The constitution is not a blank cheque for any branch. It is a set of limits, permissions and expectations. In 2026, Westminster needs fewer slogans and more accurate maps.