Paper 2 · The Constitution

The constitution: codification and sovereignty

Politics Panther · Revision walk-through

The UK constitution is unusual: uncodified, flexible, and resting on the sovereignty of Parliament. This walk-through sets out what it is and where it comes from, then takes the two debates that dominate the exam - should it be codified, and has parliamentary sovereignty survived - before mapping the reforms since 1997 and the cases that move the argument.

Hold one distinction throughout: the difference between what is legally true and what is true in practice. In strict law Parliament has never stopped being sovereign; in practice devolution, rights law and the courts have all constrained it. Most of the exam turns on that gap.

Part 1

1. The nature and sources of the UK constitution

The UK constitution is uncodified: there is no single document. It is drawn from several sources:

Statute law: Acts of Parliament of constitutional importance (the Human Rights Act 1998, the devolution Acts, the Constitutional Reform Act 2005). The most important source, because of parliamentary sovereignty.
Common law: judge-made law and legal principle built up through cases.
Conventions: long-standing but unwritten rules (the Salisbury Convention, the Sewel Convention, individual and collective ministerial responsibility).
Authoritative works (works of authority): respected texts that explain how the system works but carry no legal force - Bagehot's The English Constitution (1867), Dicey's Law of the Constitution (1885), and Erskine May on parliamentary procedure. Guides, not binding rules.
Treaties: international agreements with other states. A treaty binds the UK externally but takes effect in domestic law only when incorporated by statute (dualism) - the European Communities Act 1972 gave the EU treaties domestic force, and the Withdrawal Agreement was implemented by the EU (Withdrawal Agreement) Act 2020.

The nature and the twin pillars. The constitution is unitary (power flows from a sovereign centre, Westminster), unentrenched and uncodified - so it can be changed by an ordinary Act of Parliament with no special procedure, which is what makes it flexible. Its twin pillars are parliamentary sovereignty and the rule of law.

How the constitution developed - the key documents

Because it is uncodified, the UK constitution has grown document by document over eight centuries rather than being written at a single moment. The exam expects the milestones, and the running theme is the transfer of power.

Document	What it did and why it matters
Magna Carta 1215	Barons forced King John to accept that the monarch is not above the law and cannot tax or punish at will - the first real limit on royal power and the root of due process. The starting point of the constitution.
Bill of Rights 1689	After the Glorious Revolution, established that the Crown cannot rule without Parliament: regular parliaments, free elections, free speech in Parliament, and no taxing or suspending laws without consent. The foundation of parliamentary sovereignty - statute stands above the Crown.
Act of Settlement 1701	Secured a Protestant succession and confirmed that Parliament, not the Crown, decides who reigns; it also strengthened judicial independence by protecting judges' tenure.
Acts of Union 1707	Merged the English and Scottish parliaments into a single Parliament of Great Britain at Westminster - the origin of the unitary state.
Parliament Acts 1911 and 1949	After the Lords blocked the 1909 People's Budget, the 1911 Act removed the Lords' veto over money bills and capped its delay of other bills at two years; the 1949 Act cut that to one. Established the primacy of the elected Commons.
European Communities Act 1972	Took the UK into the EEC and gave EU law priority over UK statute (seen in Factortame, 1990) - a major qualification of sovereignty while the UK was a member.
EU (Withdrawal Agreement) Act 2020	Implemented Brexit: the UK left the EU on 31 January 2020 and the European Communities Act was repealed, ending EU-law supremacy and restoring the supremacy of statute.

The pattern. Each document shifted power - from Crown to Parliament (1215, 1689, 1701), from separate kingdoms to one (1707), from Lords to Commons (1911, 1949), and into and back out of the EU (1972, 2020). The constitution is the running total of these changes, not a single written text.

Part 2

2. Parliamentary sovereignty and Dicey

Parliamentary sovereignty is the doctrine that Parliament is the supreme legal authority. Dicey set out three rules:

Parliament can make or unmake any law on any subject;
no Parliament can bind its successor;
no body, including the courts, can override or set aside an Act of Parliament.

The doctrine has been tested. Factortame (1990) saw the courts suspend part of the Merchant Shipping Act 1988 because it conflicted with EU law - a real legal limit while the UK was a member. Devolution, the Human Rights Act, the growing use of referendums and a more active Supreme Court have all been read as challenges to it.

The recovery argument. Each limit on sovereignty proved reversible. Brexit ended the Factortame limit and restored the supremacy of statute; devolution and the HRA remain repealable by a future Parliament. In strict legal terms Parliament has never stopped being sovereign - the limits are political and practical, not legal.

Part 3

3. The codification debate - the case for

Clarity. A single written document would set out the rules citizens, lawyers and ministers can read in one place, instead of scattered statutes, cases and conventions.
Entrenched rights. Rights would be protected against an ordinary majority. The Human Rights Act is only ordinary statute - the 2022 Bill of Rights Bill tried to replace it - so rights last only as long as the next majority allows.
Constraining the executive. A codified constitution with a higher-law status would limit a government that, through a Commons majority, can currently change the constitution almost at will (the Safety of Rwanda Act 2024 legislated a fact about a country; the repeal of the Fixed-term Parliaments Act handed dissolution back to the executive).
Modern legitimacy. Most democracies have one; an entrenched document drafted now would carry democratic authority that an inherited, piecemeal constitution does not.

Part 4

4. The codification debate - the case against

Flexibility. An uncodified constitution adapts quickly through ordinary legislation - the HRA brought a whole rights framework home with a single Act; devolution was created by statute. Codified constitutions are slow to amend (the US has amended its on a substantive issue only rarely since 1971).
Parliamentary sovereignty. Codification would transfer power from elected MPs to unelected judges interpreting the document, weakening democratic control.
It works. The system has produced stable government and protected rights in practice (the Belmarsh declaration of incompatibility in 2004, Miller 2 in 2019) without a written text.
No agreement and no need. There is no consensus on what a codified constitution would contain, and the evolutionary approach has handled major change (devolution, the Supreme Court) without crisis.

The judgement axis. The debate turns on whether you value flexibility and democratic control (against) or clarity and entrenched limits on power (for). The strongest answers weigh recent cases - the Rwanda Act, the FTPA repeal, Miller 2 - as evidence for whichever side you take.

Part 5

5. Constitutional reform since 1997

Reform	What it did	Verdict
Devolution (1998 on)	Created the Scottish Parliament, Senedd and NI Assembly.	Dispersed power and improved democracy, but left the English question unresolved and is not complete.
Human Rights Act 1998	Incorporated the ECHR into UK law; courts can declare statutes incompatible.	Strengthened rights, but as ordinary statute it is not entrenched.
Lords reform 1999 and 2024	Removed most hereditary peers in 1999; the 2024 Bill removes the remaining hereditaries.	Improved legitimacy but left the chamber unelected - reform unfinished.
Constitutional Reform Act 2005	Created the UK Supreme Court (opened 2009) and reformed the Lord Chancellor's role.	Improved the separation of powers - one of the more complete reforms.
Fixed-term Parliaments Act 2011 (repealed 2022)	Set five-year fixed terms; repealed in 2022, returning dissolution to the prerogative.	Its repeal shows how easily constitutional change is undone without entrenchment.
2024 Labour programme	Hereditary peers removal and further proposed reform.	Continues the unfinished agenda; dispersed power further but rights largely untouched.

The pattern. Reform since 1997 has dispersed power and modernised institutions, but almost nothing has been entrenched and much is incomplete - which is itself the strongest evidence for the codification case.

Part 6

6. Key cases and Acts

Case or Act	What it established
Factortame (1990)	The courts suspended part of an Act because it breached EU law - a real legal limit on sovereignty while the UK was an EU member, ended by Brexit.
Human Rights Act 1998	Brought ECHR rights into UK courts; courts can issue declarations of incompatibility (Belmarsh, 2004). Ordinary statute, so repealable.
Constitutional Reform Act 2005	Created the UK Supreme Court and reformed the Lord Chancellor - a clearer separation of powers.
Miller 1 (2017)	The government needed Parliament's authority to trigger Article 50 - the executive cannot use the prerogative to remove statutory rights.
Miller 2 / Cherry (2019)	The 2019 prorogation of Parliament was unlawful - the courts limiting the executive's use of the prerogative.
Safety of Rwanda Act 2024	Legislated that Rwanda is a safe country, showing the reach of a sovereign Parliament with a Commons majority.

Part 7

7. Exam method - the 30-marker

Know which question you have. Codify or not; sovereignty undermined or intact; reform since 1997 a success or not. Each needs a slightly different spine.
Use the same evidence across all three: the HRA, Factortame, Miller 1 and 2, the CRA 2005, the FTPA repeal, devolution, the Rwanda Act.
For sovereignty, distinguish legal from political. In strict law Parliament remains sovereign; the limits are political and practical. That distinction reaches the top band.
Reach interim judgements at the end of each theme and hold a clear line of argument, rather than saving it for the conclusion.

The verdicts that travel. On sovereignty: limited in practice, intact in law. On codification: the choice is flexibility and democratic control against clarity and entrenched limits. On reform since 1997: real modernisation, but unfinished and unentrenched. The interactive codification grid and sovereignty grid drill the judgements.

Worked essay - Evaluate the view that the UK should adopt a codified constitution (30 marks)

Line of argument. The UK should not adopt a fully codified constitution: flexibility and democratic control outweigh the gains. The strongest part of the reformers' case is not a whole written document but the targeted entrenchment of rights.

Theme 1 - flexibility against clarity

An uncodified constitution adapts through ordinary legislation: the Human Rights Act brought a whole rights framework home with a single Act, and devolution was created by statute, where the United States has amended its document on a substantive issue only rarely since 1971. The cost is clarity - the rules sit across scattered statutes, cases and conventions. Interim judgement: for a polity that has changed as fast as the UK since 1997, flexibility is worth more than tidiness.

Theme 2 - democratic control against entrenched limits

Codification would transfer interpretive power from elected MPs to unelected judges reading the document. Against that, a government with a Commons majority can currently reshape the constitution almost at will - the Safety of Rwanda Act 2024 legislated a fact about a country, and the repeal of the Fixed-term Parliaments Act handed dissolution back to the executive. Interim judgement: democratic control favours the present system, but the lack of any higher-law check on the executive is the reformers' strongest ground.

Theme 3 - the track record against the erosions

The system has produced stable government and protected rights in practice without a written text - the Belmarsh declaration of incompatibility in 2004, Miller 2 limiting prorogation in 2019. Yet the Human Rights Act is only ordinary statute, repealable by the next majority, and reform since 1997 is largely unentrenched and unfinished. Interim judgement: the constitution works, but rights protection is fragile in a way codification would fix.

Judgement. The case against a fully codified constitution holds: flexibility and democratic accountability are real strengths, and there is neither agreement on what a written document would contain nor evidence the present system has failed. But the reformers are right that rights and the limits on executive power rest on nothing more than an ordinary majority. The strongest reform is targeted - entrenching rights - rather than a wholesale codified constitution.

🧠 MCQ quiz15 questions across the constitution, sovereignty, codification and reform. 📊 Codification gridPredict and check six episodes against the case for codification, then test yourself.