The constitution and the British constitution: sources, features, conventions and the Rule of Law

1. A constitution: meaning, importance and parts

A constitution is the body of fundamental rules that sets up the organs of government, divides power among them, and fixes the relation between the government and the citizen. K.C. Wheare, in Modern Constitutions, uses the word in two senses: the whole system of government of a country, and the particular document in which most of those rules are collected.

Its importance lies in four functions:

• it creates the legislature, executive and judiciary and gives them their powers;
• it limits power, so that government acts within law (constitutionalism);
• it protects rights, either through a bill of rights or through conventions and the courts;
• it gives the state legitimacy and stability, because its rules are harder to change than ordinary law.

A typical written constitution has these parts: a preamble stating its source and purpose; the organisation of the legislature, executive and judiciary; the distribution of power between centre and units (in a federation); a statement of rights; and an amendment procedure. Constitutions are classified as written or unwritten, rigid or flexible, federal or unitary. Britain is the standard example of an unwritten, flexible and unitary constitution; the United States of a written, rigid and federal one.

2. Britain: a very brief history

The British constitution was never made at one sitting. It grew. The landmarks a student should be able to list in order are:

1. Magna Carta, 1215 — the barons force King John to accept that the King is under the law.
2. Petition of Right, 1628 — no taxation without Parliament, no arbitrary imprisonment.
3. Glorious Revolution and the Bill of Rights, 1689 — the supremacy of Parliament over the Crown.
4. Act of Settlement, 1701 — Protestant succession and security of tenure for judges.
5. Reform Acts, 1832 onwards — the widening of the franchise, ending in universal adult suffrage in 1928.
6. Parliament Acts, 1911 and 1949 — the House of Lords loses its veto over Commons bills.
7. Devolution (1998) and the Constitutional Reform Act, 2005 — Scottish, Welsh and Northern Irish legislatures; a separate Supreme Court from 2009.

3. Sources

• Historic documents and charters — Magna Carta, the Bill of Rights.
• Statutes — Acts of Parliament on constitutional matters, such as the Parliament Acts, the Representation of the People Acts, the Human Rights Act 1998, and the Dissolution and Calling of Parliament Act 2022.
• Judicial decisions — the common law on liberty and on the limits of the prerogative.
• Conventions — the unwritten rules of political practice (section 5).
• Authoritative writings — Bagehot, Dicey, Erskine May on parliamentary practice.

4. Salient features

1. Unwritten. There is no single document called the constitution. Much of it is written in statutes; what is missing is a single, superior text.
2. Evolutionary. It is the product of growth over centuries rather than of a constituent assembly.
3. Flexible. Parliament amends constitutional law by an ordinary Act, by simple majority.
4. Parliamentary sovereignty. Parliament can make or unmake any law, and no court can strike down an Act of Parliament.
5. Unitary. Power rests in Westminster; devolved bodies exist by Act of Parliament and can in law be altered by it.
6. Constitutional monarchy. The King reigns but does not rule.
7. Parliamentary (cabinet) government. The executive is drawn from, and responsible to, the House of Commons.
8. Fusion of powers. Bagehot’s “close union, the nearly complete fusion” of executive and legislature, the Cabinet being the link.
9. Rule of Law in place of a bill of rights (section 6).
10. Contrast between theory and practice. The law gives the Crown wide power; convention transfers it to ministers.

5. Conventions: meaning, importance and landmarks

Dicey defined conventions as “understandings, habits or practices” which regulate the conduct of the Crown, ministers and other officials, but which are not enforced by the courts. They are rules of political morality. Jennings asked three questions to identify one: what are the precedents, did the actors believe themselves bound, and is there a reason for the rule?

Why they are obeyed. Dicey’s answer was that breach of a convention would soon lead to a breach of law (a government that did not summon Parliament would soon have no lawful money to spend). Jennings added public opinion and the fear of political loss.

Landmark conventions.

• The monarch gives the royal assent to every bill passed by Parliament. The last refusal was by Queen Anne in 1708 (Scottish Militia Bill).
• The monarch acts on the advice of ministers.
• The monarch appoints as Prime Minister the leader of the party that commands a majority in the Commons, and the Prime Minister sits in the Commons (no peer has been Prime Minister since Lord Salisbury, who left office in 1902).
• Collective responsibility of the Cabinet to the Commons, and individual ministerial responsibility for a department.
• A government defeated on a vote of no confidence resigns or seeks a dissolution.
• The Salisbury convention: the Lords do not reject at second reading a bill carrying out a manifesto promise of the elected government.
• The Sewel convention: Westminster will not normally legislate on devolved matters without the consent of the devolved legislature.

Importance. Conventions adapt an old legal framework to democracy without formal amendment. The law still says the Crown chooses ministers, dissolves Parliament and assents to bills; convention makes these the decisions of a government answerable to the elected House. In short, the law gives the form, convention gives the working constitution.

6. The Rule of Law

A.V. Dicey, in Introduction to the Study of the Law of the Constitution (1885), gave the Rule of Law three meanings:

1. Supremacy of regular law as opposed to arbitrary power: no one can be punished except for a distinct breach of law established in the ordinary courts.
2. Equality before the law: every person, official or private, is subject to the ordinary law administered by the ordinary courts. Dicey contrasted this with the French droit administratif, under which officials were judged by separate administrative courts.
3. The constitution is the result of the ordinary law: rights in Britain come from judicial decisions in particular cases, not from a written declaration.

Criticism. Jennings and others pointed out that wide discretionary power is unavoidable in a modern state; that public officers do have special powers and immunities; that Britain itself developed tribunals; and that Dicey misread droit administratif, which in practice protects the citizen well. Today the Rule of Law in Britain is applied through judicial review of executive action. R (Miller) v The Prime Minister (2019), in which the Supreme Court held the prorogation of Parliament unlawful, is the modern illustration. The Constitutional Reform Act 2005 also refers to the Rule of Law as an existing constitutional principle.

How this is examined

Three shapes recur. An essay on the salient features of the British constitution; an essay on the significance of conventions and how they influence the working of the political system (Unit I, February 2025); and a short note on the Rule of Law in the UK (January 2026, Q.8(a)). For the conventions answer, give Dicey’s definition, five named conventions, why they are obeyed, and end with the law-and-convention contrast. For the Rule of Law, write the three meanings in order, then two lines of criticism.