What a Constitution Does

A constitution is the set of rules, principles and laws that establishes how a political system works. It answers four central questions:

In AQA Politics, the "nature and sources" of the British constitution means two linked things. The nature is what kind of constitution the UK has. The sources are the places where constitutional rules are found and the kinds of authority those rules have.

The UK constitution is unusual because it is not contained in one single constitutional document. It is built from Acts of Parliament, court judgments, conventions, prerogative powers, historical documents and authoritative writings. That does not mean the UK has no constitution. It means the constitution is dispersed.

Key vocabulary for this split:

Active reading: Why is it more accurate to call the UK constitution "uncodified" than simply "unwritten"?

Codified and Uncodified Constitutions

The UK constitution is often described as "unwritten", but that is misleading. Much of it is written down in statutes, judgments, parliamentary rules and government documents. The more accurate description used by UK Parliament is that it is partly written and wholly uncodified.

A codified constitution normally has three features:

The UK does not fully fit any of those features. There is no single constitutional text. No ordinary court can strike down an Act of Parliament just because it conflicts with a higher constitution. Most constitutional change can be made by ordinary Acts of Parliament.

This gives the UK constitution a distinctive character:

The flexibility of an uncodified constitution can be an advantage. It allows constitutional rules to adapt to political pressure and changing circumstances without the difficulty of a rigid amendment procedure. It can also be criticised. If a government controls a disciplined majority in the House of Commons, it may be able to alter important constitutional rules quickly.

A simple process map shows why statute matters so much in the UK:

The important point is that the UK does not need a separate constitutional amendment procedure. Constitutional law can be made through ordinary parliamentary law-making.

Active reading: Give one benefit and one risk of a flexible uncodified constitution.

Main Sources of the British Constitution

The British constitution has several sources. They are not all equal. Some are legally binding, some are politically binding, and some are influential because they help explain uncertain rules.

Statute is the most important legal source because of parliamentary sovereignty. If Parliament passes a clear Act, courts apply it. That does not make other sources irrelevant. Common law, conventions and authoritative opinions often shape how the constitution operates before Parliament chooses to legislate.

The Cabinet Manual is a useful example of the UK constitution's mixed character. It sets out laws, rules and conventions affecting government. It is authoritative because it is an official guide for ministers and civil servants, but it is not itself legally binding and does not create the rules it describes.

The royal prerogative is another good example. It is a legal source of executive power, not just a tradition. However, prerogative power is weaker than statute. In Miller I, the Supreme Court held that ministers could not use prerogative power to trigger Article 50 if doing so would change domestic law and remove rights created by statute. Parliament had to authorise the step through an Act.

The hierarchy can be summarised like this:

Active reading: Which source is legally strongest in the UK constitution, and why?

Historical Documents

AQA expects awareness of four historical documents or groups of documents. They matter because they show that the British constitution developed gradually through struggles over monarchy, Parliament, law and rights. They are not a single codified constitution. They are constitutional landmarks.

Magna Carta should be used carefully. It was not a democratic constitution and it did not create modern equal rights. Its importance is that it became a symbol and early legal expression of the idea that rulers are subject to law.

The Bill of Rights and Act of Settlement are more directly connected to constitutional monarchy. They helped move power away from personal monarchy and towards Parliament and law. The monarch remained part of the constitution, but royal power became increasingly constrained.

The Parliament Acts show that constitutional change can alter relationships within Parliament itself. Before 1911, the House of Lords could block legislation passed by the elected Commons. The 1911 Act removed the Lords' absolute veto over most public bills and the 1949 Act reduced the delaying period further. This strengthened the elected Commons without creating a codified constitution.

Historical development can be shown as a simple progression:

The thread running through these documents is not one sudden founding moment. It is the gradual movement from arbitrary personal rule towards government through Parliament, law and constitutional principle.

Active reading: Which historical document best illustrates the rule of law, and which best illustrates Commons primacy?

Rule of Law and Parliamentary Sovereignty

The two core principles for this split are rule of law and parliamentary sovereignty. They often support each other, but they can also create tension.

Rule of law means more than "there are laws". A dictatorship can have many laws. In UK constitutional politics, rule of law means power is exercised according to law rather than personal will.

The core elements are:

Parliamentary sovereignty is a legal principle about Parliament's law-making authority. It means:

These principles often work together. Parliamentary sovereignty prevents ministers from claiming they can govern by personal authority. If a major legal change is needed, ministers normally need statutory authority. That supports the rule of law because executive power must have a legal basis.

Miller I is the clearest modern example for this lesson. The government argued that it could use prerogative power to notify the EU of the UK's intention to leave. The Supreme Court held that ministers could not use prerogative power to bring about changes in domestic law where statute was needed. Parliament responded by passing the European Union (Notification of Withdrawal) Act 2017. The case shows three points:

Miller/Cherry in 2019 also shows that prerogative powers may have legal limits. The Supreme Court held that proroguing Parliament was unlawful where it frustrated Parliament's ability to perform its constitutional functions without reasonable justification. For this split, the point is not to study judicial power in depth. The point is that an uncodified constitution can still generate legal principles that control executive action.

There is also a tension. If Parliament is legally sovereign, it can pass laws that critics think damage rights, weaken accountability or reduce legal certainty. The rule of law can guide interpretation and political criticism, but parliamentary sovereignty means courts generally cannot invalidate a clear Act of Parliament.

Active reading: Does parliamentary sovereignty mainly protect the rule of law, or can it threaten it? Give one reason.

AQA Analysis

For AQA answers, avoid treating the constitution as a memory list. The stronger approach is to make a claim, use precise vocabulary, apply evidence, and then explain the significance.

High-quality analysis often turns on three tensions:

A strong paragraph on the sources of the constitution could be built like this:

Use these distinctions in exam answers:

A concise overall judgement for this split:

Active reading: Write one sentence beginning, "The most important source of the British constitution is..." and include one piece of evidence.