Sources and nature of the constitution

The first task in UK Constitutional Law is to understand what sort of constitution the United Kingdom has. The answer is not simply that it is “unwritten”. That phrase is at best shorthand and at worst misleading. Much of the constitution is written: Acts of Parliament, statutory instruments, treaties, judicial decisions, parliamentary materials, ministerial codes, devolution legislation and human rights instruments all contain constitutional rules. What the United Kingdom lacks is a single entrenched constitutional code with special legal status over ordinary legislation.

The UK constitution is therefore better described as uncodified, historically cumulative and politically sustained. It consists of legal rules, political conventions, institutional practices and constitutional principles. Some of these are directly enforceable in court. Others are not legally enforceable but remain constitutionally obligatory. The monarch must appoint as Prime Minister the person best able to command the confidence of the House of Commons; ministers must account to Parliament; the House of Lords does not normally block manifesto legislation; judges must decide cases independently. These propositions do not all have the same legal source, but each helps to structure constitutional government.

The module’s central concern is the relationship between citizen, Parliament, executive and courts. Week 1 supplies the grammar for that relationship. Parliament is commonly said to be legally sovereign: it may make or unmake any law, and no person or body is recognised by the courts as having a right to override or set aside an Act of Parliament. The executive governs through powers derived from statute and prerogative, but it must identify a lawful source for what it does. The courts interpret legislation, control administrative legality and articulate constitutional principles such as legality, access to justice and the rule of law. The citizen is not merely a subject of state power but a rights-holder able, in appropriate circumstances, to challenge public action.

For Durham first-year students, this topic is foundational. Contract and Tort teach private-law method: identifying duties, obligations, breaches and remedies. UK Constitutional Law requires the same discipline, but the legal actors are institutions of state. A good answer in this module never asserts that something is “unconstitutional” as if that were self-explanatory. It asks: unconstitutional in what sense? Contrary to statute? Contrary to common law principle? Contrary to convention? Contrary to the rule of law? Politically improper but legally valid? That distinction between legal invalidity and political constitutional criticism will recur throughout the year, especially in judicial review, devolution, human rights and the separation of powers.

The nature of the UK constitution cannot be understood apart from its historical development. Unlike the United States, the UK did not adopt a constitutional text at a founding moment. Its constitution emerged from conflict between Crown, Parliament, courts and people. The result is a constitutional order in which legal doctrine often bears the marks of political settlement.

Medieval constitutionalism was not democratic in any modern sense, but it established an important idea: public power is not merely personal will. Magna Carta 1215, especially in its later reissues, became a symbol of lawful government and due process. Its contemporary legal force is limited, but its constitutional significance lies in the claim that even rulers act within law. That theme later appears in the seventeenth-century struggle between royal prerogative and parliamentary authority.

The Case of Proclamations in 1610 is a classic illustration. The Crown claimed power to legislate by proclamation. Coke CJ rejected that claim. The monarch could not create new offences or alter the law by prerogative. The case is not a modern judicial review decision, but its constitutional meaning remains central: executive power requires legal authority. A ruler cannot make law merely by announcing it.

The seventeenth century then produced the Petition of Right 1628, the Civil War, the execution of Charles I, the Restoration, the Glorious Revolution and the Bill of Rights 1688. The Bill of Rights is a constitutional statute because it limits the Crown and confirms key parliamentary privileges. Its famous provision on freedom of speech in Parliament remains central to Article 9 parliamentary privilege. The settlement after 1688 did not create popular sovereignty. It created, rather, the legal supremacy of the Crown in Parliament and the political centrality of parliamentary government.

The eighteenth and nineteenth centuries transformed that settlement. Cabinet government developed; the monarch’s personal discretion diminished; the Prime Minister became central; political parties disciplined parliamentary life; the franchise expanded; and ministerial responsibility became a core convention. Dicey’s late nineteenth-century account of parliamentary sovereignty and the rule of law reflected this world. For Dicey, the constitution’s strength lay in ordinary law, parliamentary supremacy and judicial control of official action. Yet Dicey underplayed empire, class, gender exclusion and the political foundations of constitutional practice.

The twentieth century complicated the orthodox picture. The growth of the administrative state meant that public power increasingly operated through delegated legislation, regulatory bodies and ministerial discretion. The welfare state required a more active executive. The UK’s accession to the European Communities in 1973, the Human Rights Act 1998, devolution to Scotland, Wales and Northern Ireland, reform of the House of Lords, creation of the Supreme Court and Brexit all reshaped the constitutional landscape. None abolished parliamentary sovereignty in orthodox legal form, but each made it harder to describe the constitution as merely Parliament plus common law.

The contemporary constitution is thus layered. Older principles remain important, but they operate within modern structures: rights adjudication, devolved autonomy, judicial review, international obligations and political accountability. In exams, avoid a Whiggish story in which history inevitably produces liberty. The better account is more contested. The constitution is an accumulation of settlements, compromises and institutional habits, some legally enforceable and some politically fragile.

Five principles dominate the opening topic: parliamentary sovereignty, the rule of law, separation of powers, constitutional monarchy and responsible government, and the distinction between law and convention. Each must be handled with precision.

Parliamentary sovereignty is the orthodox starting point. In Diceyan form it means that Parliament may make or unmake any law whatever, and that no person or body has legal authority to override or set aside its legislation. “Parliament” here means the Crown in Parliament: King, House of Lords and House of Commons acting through the legislative process. It does not mean the House of Commons alone. Nor does it mean that Parliament is politically omnipotent. A sovereign Parliament may lawfully enact oppressive or foolish legislation; that does not mean it can secure obedience, avoid electoral punishment or escape constitutional criticism.

The courts give effect to parliamentary sovereignty by recognising Acts of Parliament as supreme legal sources. Yet the modern law qualifies the simple picture. Some statutes are treated as constitutional statutes, not impliedly repealed by later inconsistent ordinary legislation unless Parliament uses clear words. European Union law, while applicable, required courts to disapply inconsistent domestic legislation because Parliament had authorised that effect through the European Communities Act 1972. Human Rights Act review permits declarations of incompatibility but not invalidation of primary legislation. Devolution legislation restricts devolved institutions but preserves Westminster’s legal power to legislate. The key point is that sovereignty remains the organising doctrine, but its operation is mediated by statutory interpretation, constitutional statutes and institutional practice.

The cases in this topic do not form a neat chronology of judicial triumph. They show how courts have articulated constitutional principles while remaining within an order formally committed to parliamentary sovereignty.

The Case of Proclamations establishes the negative principle that the executive cannot alter law by unilateral command. It is often cited for the proposition that prerogative power is limited by common law. Its significance for modern public law is methodological: begin with legal authority. If government claims power, the court asks for its source.

Entick v Carrington develops that point in relation to liberty and property. State officers broke into Entick’s house and seized papers under a warrant issued by the Secretary of State. The court held the action unlawful. The case is an enduring authority for the proposition that executive interference with the individual requires lawful justification. Private persons may generally do anything not prohibited by law; public officials must point to positive authority for coercive action.

Council of Civil Service Unions v Minister for the Civil Service, the GCHQ case, marks a modern shift. The House of Lords accepted that prerogative powers can in principle be reviewable, although national security justified non-intervention on the facts. Reviewability depends less on the power’s source than on its subject matter. That matters greatly in a constitution where major executive powers still derive from prerogative.

Thoburn v Sunderland City Council introduced the language of constitutional statutes. Laws LJ held that certain statutes condition the legal relationship between citizen and state or enlarge or diminish fundamental rights, and therefore are not subject to implied repeal. The doctrine does not entrench such statutes absolutely. Parliament may repeal them expressly. Its importance lies in rejecting a purely flat view of the statute book.

Jackson v Attorney General is doctrinally delicate. The validity of the Hunting Act 2004 was challenged on the basis that the Parliament Act 1949 was invalid. The challenge failed. The case is famous because several Law Lords made observations about possible limits to parliamentary sovereignty. Those observations are not a simple holding that courts may strike down Acts of Parliament. They are better read as evidence that senior judges no longer regard Diceyan sovereignty as entirely immune from conceptual pressure.

R (Miller) v Secretary of State for Exiting the European Union concerned whether ministers could trigger Article 50 TEU using prerogative power. The Supreme Court held that they could not because withdrawal would change domestic law and remove statutory rights created under the European Communities Act 1972. An Act of Parliament was required. The case reaffirms, rather than rejects, parliamentary sovereignty: ministers cannot use prerogative power to frustrate a statutory scheme.

R (Miller) v Prime Minister; Cherry v Advocate General for Scotland concerned prorogation of Parliament. The Supreme Court held that the advice to prorogue was justiciable and unlawful because it frustrated Parliament’s constitutional functions without reasonable justification. The decision shows courts enforcing structural constitutional principles: parliamentary accountability, legality and limits on prerogative. It remains controversial not because it abandoned law, but because it located legal limits in constitutional principle rather than detailed statutory text.

See practice questions section below.

See further reading section below.