Sources and nature of the constitution

This first week is conceptual. It asks what the United Kingdom constitution is, where it is found, and how constitutional argument works when there is no single codified constitutional instrument. For Durham students beginning The Individual and the State, the point is not to memorise a list of sources. It is to acquire a method: when government action is challenged, one must identify the legal source of the power, the legal limits upon that power, the institutional actor responsible for enforcing those limits, and the constitutional principle that explains why the challenge matters.

The United Kingdom constitution is often described as uncodified. That is preferable to saying that it is unwritten. Much of it is written: statutes, delegated legislation, treaties, judicial decisions, ministerial codes, standing orders, devolution instruments, prerogative materials, and official guidance. What it lacks is a single entrenched document, adopted at a founding moment, ranked formally above ordinary legislation and enforceable by a constitutional court empowered to strike down inconsistent Acts of Parliament. The absence of such a document does not mean the absence of constitutional law. It means that constitutional law is dispersed across sources of different legal status.

Three distinctions are essential. First, legal rules must be distinguished from political conventions. A legal rule is enforceable by a court. A convention may be binding in constitutional morality and political practice, but courts ordinarily recognise rather than enforce it. Secondly, legal validity must be distinguished from political legitimacy. Parliament may have legal power to enact legislation that is politically indefensible. Thirdly, constitutional sources must be distinguished from constitutional principles. A statute is a source. Parliamentary sovereignty, the rule of law, separation of powers, responsible government and legality are principles used to interpret and organise sources.

The module’s larger concern is the relationship between the citizen and the state. Week 1 therefore supplies the architecture for later topics: judicial review, human rights, prerogative power, legitimate expectations, procedural fairness, access to justice, and state liability. A citizen challenging government action rarely says simply that the constitution has been breached. The claim is more precise: the minister lacked statutory authority; the decision was ultra vires; a relevant consideration was ignored; a fundamental right was infringed; Parliament did not use clear words; the decision-maker acted for an improper purpose; or an ouster clause cannot exclude judicial supervision of jurisdictional error. Each of those arguments presupposes a theory of constitutional authority.

The central tension is between parliamentary sovereignty and constitutionalism. Dicey’s orthodox account treats Parliament as legally unlimited: it may make or unmake any law, and no person or body may override its legislation. Yet modern public law also insists that public power must be legally authorised, rationally exercised, fairly administered and compatible, where possible, with fundamental rights. The courts do not generally strike down Acts of Parliament, but they do police the legality of executive action and interpret legislation against a background of constitutional principle. The result is neither a purely political constitution nor a fully judicialised one. It is a constitution in which law and politics are interdependent, and in which institutional restraint is as important as formal power.

The modern constitution cannot be understood without its historical antagonism to arbitrary executive power. The key constitutional story is not the creation of the state by a single written document, but the gradual subjection of public authority to law. Medieval and early modern materials matter because they established the idea that even royal power was not merely personal will. Magna Carta 1215 is often invoked symbolically; its continuing legal importance is limited, but its constitutional memory is significant. More doctrinally important is the seventeenth-century settlement.

The Case of Proclamations in 1610 is foundational because it rejected the proposition that the Crown could alter law by proclamation. The monarch possessed only those prerogative powers recognised by law. That proposition remains central to modern judicial review of prerogative power. The Petition of Right 1628 protested taxation and imprisonment without lawful authority. The Civil War and the execution of Charles I exposed the unresolved conflict between Crown, Parliament and courts. The Restoration did not settle the matter. The Glorious Revolution of 1688–89 produced the Bill of Rights and confirmed that government required parliamentary authority, especially in relation to taxation, standing armies and interference with parliamentary proceedings.

The constitutional order that emerged was not democratic in the modern sense. It was parliamentary and anti-absolutist, not egalitarian. The franchise remained narrow; women were excluded; many citizens had little practical political voice. Nevertheless, legal limits on executive action were developing. Entick v Carrington is the classic eighteenth-century authority. State officials entered Entick’s property under a general warrant. The court held that executive action required legal authority. The case is now a canonical expression of the principle that the state may do only what law permits, whereas the individual may do anything not prohibited by law.

Nineteenth-century constitutionalism added two further features. First, the cabinet system matured. The executive became formally appointed by the Crown but politically dependent on confidence in the House of Commons. Secondly, Dicey systematised the constitution around parliamentary sovereignty and the rule of law. Dicey’s account remains indispensable, but it was never a neutral description of all constitutional reality. It reflected Victorian assumptions: unitary government, parliamentary supremacy, limited administrative state, and confidence in ordinary courts rather than specialised constitutional adjudication.

The twentieth century transformed that settlement. Universal suffrage, mass political parties, the welfare state, delegated legislation, administrative tribunals, national security powers and European integration all altered the practical balance between citizen and state. Parliament remained legally sovereign, but much law-making occurred through executive-dominated legislative processes. Judicial review expanded in response. The courts developed grounds of review to control discretion without claiming general appellate authority over merits.

Late twentieth- and early twenty-first-century developments made the constitution more visibly plural. The European Communities Act 1972 gave EU law domestic effect until Brexit. The Human Rights Act 1998 required courts to interpret legislation compatibly with Convention rights where possible and to review public authorities for rights compliance. Devolution created legislatures and executives in Scotland, Wales and Northern Ireland with powers limited by statute. The Constitutional Reform Act 2005 reconfigured the office of Lord Chancellor and created the Supreme Court, symbolically separating final adjudication from the legislature. Brexit then removed EU supremacy as a continuing domestic source but confirmed the centrality of constitutional method: the Miller litigation asked who had legal authority to trigger Article 50 and whether prorogation was justiciable. The historical lesson is that the UK constitution evolves through conflict between institutions, with courts translating political settlements into legal propositions.

1. An uncodified but legal constitution. The UK constitution is not contained in one supreme instrument. Its sources include Acts of Parliament, common law principles, prerogative powers, constitutional conventions, works of authority, parliamentary materials, international obligations, and, historically, EU law. The first analytical task is to classify the source. A statutory rule has different legal force from a convention; a common law principle has different status from a ministerial code; a treaty has no domestic effect unless incorporated by legislation. Many weak answers fail because they use the word constitutional as if it automatically means legally enforceable.

1. Parliamentary sovereignty. The orthodox legal principle is that Parliament may enact or repeal any law, and no court may invalidate an Act of Parliament. The doctrine concerns legal validity, not political wisdom. It does not mean that ministers are sovereign; ministers are subordinate to statute and common law. Nor does it mean that Parliament normally governs directly. In practice, government often controls the Commons agenda, but legal sovereignty remains attributed to the Queen-in-Parliament, now the King-in-Parliament. The doctrine also includes implied repeal: where two ordinary statutes conflict, the later prevails to the extent of inconsistency. Thoburn qualifies that rule for constitutional statutes: they are not impliedly repealed, though they may be expressly repealed.

1. The rule of law. The rule of law is both a legal principle and a constitutional ideal. At minimum, it requires that public power be authorised by law, that law be accessible and relatively certain, and that courts be able to determine legality. Dicey associated it with the absence of arbitrary power, equality before ordinary law, and the constitution as a product of ordinary judicial decisions. Modern accounts add access to courts, fair procedures, legality, respect for fundamental rights, and limits on discretionary power. The rule of law is not a single rule yielding automatic answers. It is an argumentative principle that courts use when construing statutes, supervising executive action, and resisting attempts to exclude judicial review.

The cases in this topic should be read as building blocks of constitutional method rather than isolated authorities. The Case of Proclamations establishes the anti-absolutist premise: executive power is legally limited. It is the historical ancestor of the modern proposition that ministers require legal authority for what they do. Entick v Carrington translates that premise into the citizen-state relationship. State officials cannot justify coercive interference with liberty or property by invoking reasons of state. They must point to law.

Madzimbamuto is the orthodox statement of parliamentary sovereignty in imperial context. Its importance lies in the distinction between legal power and constitutional propriety. A court may acknowledge that certain legislation would be unconstitutional in a political sense while still accepting that Parliament has legal authority to enact it. That distinction remains examinable, particularly when students conflate sovereignty with legitimacy.

Fire Brigades Union shows that executive power is not merely controlled by express statutory limits. A minister may not use prerogative or administrative schemes so as to frustrate the will of Parliament embodied in legislation. This case is an early modern example of courts using constitutional principle to supervise executive discretion in the shadow of statute.

Thoburn is significant because it introduced the language of constitutional statutes into domestic public law. Laws LJ did not deny parliamentary sovereignty. He altered the ordinary rule of implied repeal by distinguishing ordinary statutes from constitutional statutes. This is a modest but important common law adjustment to the hierarchy of sources.

Jackson is essential for understanding contemporary debate. The House of Lords upheld the validity of the Hunting Act 2004 enacted under the Parliament Acts. The broader significance is found in obiter remarks questioning whether parliamentary sovereignty remains absolute in every conceivable circumstance. These remarks do not amount to a judicial power to strike down Acts of Parliament. They do show that senior judges regard the rule of law as a constitutional principle capable of shaping, and perhaps limiting at the margins, orthodox theory.

Miller I and Miller II are the leading modern authorities on constitutional structure. Miller I held that ministers could not use prerogative power to trigger Article 50 where doing so would alter domestic law and remove statutory rights created by the European Communities Act 1972. The case reaffirmed parliamentary sovereignty by requiring legislation before withdrawal notification. Miller II held that the prorogation of Parliament was justiciable and unlawful because it frustrated Parliament’s constitutional functions without reasonable justification. Together, the Miller cases show how courts police the legal boundaries between Parliament and executive without claiming a general political veto.

See practice questions section below.

See further reading section below.