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This lesson examines the relationship between the judiciary and Parliament in the UK political system. For Edexcel A-Level Politics, Component 2 (UK Government, Section A), this relationship is one of the richest sources of evaluation, because it is defined by the tension between two fundamental constitutional principles that pull in opposite directions: parliamentary sovereignty and the rule of law. Sovereignty says that Parliament is the supreme legal authority and that no court may override its Acts; the rule of law says that everyone, including Parliament's government, must act within and be accountable under law. Most of the time these principles coexist comfortably, but at the edges — when a statute appears to violate rights, or when Parliament legislates to reverse a judicial finding — they collide. Understanding how the UK constitution manages that collision, chiefly through statutory interpretation and the Human Rights Act, is central to answering questions about whether the judiciary is too powerful, too deferential, or appropriately balanced against the elected legislature.
Parliamentary sovereignty is the cornerstone of the UK constitution. As formulated by the constitutional theorist A. V. Dicey, it has three limbs:
The decisive practical consequence for this topic is that, unlike the US Supreme Court, the UK Supreme Court cannot strike down an Act of Parliament. Even where a statute plainly breaches fundamental rights, the courts cannot invalidate it. The strongest action available is a declaration of incompatibility under the Human Rights Act 1998 — a formal signal that the law breaches Convention rights, which Parliament is under no legal obligation to act upon.
Key Term: Parliamentary sovereignty is the principle that Parliament is the supreme legal authority, able to create or end any law, and that no court may override an Act of Parliament.
This is why the UK Supreme Court is not a constitutional court in the American sense. In the US, the codified Constitution is the supreme law, and the courts may declare statutes unconstitutional and void. In the UK, Parliament itself is supreme, so the courts interpret and apply legislation but may never set it aside. This single contrast underpins much of the evaluation in this topic, and a candidate who keeps it sharp avoids the most common and most damaging error in the whole unit.
Sovereignty is sometimes said to have been eroded in recent decades, and a strong answer can engage with this without overstating it. EU membership, while it lasted, gave EU law supremacy over conflicting statute (the Factortame position) — but Brexit reversed this, and the European Communities Act 1972 has been repealed, so the supremacy of Parliament has if anything been reasserted. Devolution has transferred wide powers to Scotland, Wales, and Northern Ireland, and the Sewel convention holds that Westminster will not normally legislate on devolved matters without consent — yet this is a convention, not a legal limit, and the Supreme Court confirmed in the Miller I litigation that it is not legally enforceable. The Human Rights Act gives the courts strong interpretive powers, but it was deliberately designed to preserve sovereignty through the non-binding declaration. The honest conclusion is that sovereignty has been qualified in practice by these developments while remaining intact in strict law: Parliament could, by ordinary legislation, repeal the HRA, abolish a devolved legislature, or reverse any judicial ruling. That legal supremacy, however politically constrained, is what keeps the judiciary subordinate.
The rule of law holds that all persons and institutions — including the government and Parliament's ministers — must be subject to and accountable under the law. The judiciary is the guardian of the rule of law, ensuring that the government acts within its legal powers, that citizens are treated equally before the law, and that no one is punished without lawful authority.
The tension with sovereignty is structural. Because Parliament can in theory pass any law, it can in theory pass laws that offend the rule of law — laws that discriminate, that remove rights without compensation, or that restrict access to justice. The courts cannot prevent Parliament from doing so. The most they can do is interpret such laws narrowly, signal incompatibility with rights, and rely on the political and reputational pressure that follows. The rule of law, in the UK, is therefore enforced robustly against the executive but only persuasively against Parliament itself.
It is worth being precise about what the rule of law requires, because vague invocations of it earn few marks. Dicey's classic formulation has three elements: that no one may be punished except for a distinct breach of law established before the ordinary courts (no arbitrary power); that all persons, whatever their rank or office, are subject to the same law and the same courts (equality before the law); and that, in the UK, constitutional protections emerge from ordinary law and judicial decisions rather than from an abstract codified document. Modern accounts add further elements — that laws should be clear, prospective, and publicly accessible, and that there should be access to independent courts to resolve disputes. The judiciary gives practical content to all of these, which is why cases such as UNISON (2017), defending access to justice, and M v Home Office (1993), insisting that ministers obey court orders, are properly understood as rule-of-law cases rather than mere administrative-law technicalities. The deeper significance is that, in the absence of a codified constitution acting as higher law, it falls to the courts to keep these principles real — a guardianship that is itself a source of the judiciary's raised profile and of the "too powerful" debate.
When Parliament passes legislation, it falls to the judiciary to interpret what that legislation means and to apply it to concrete cases. Because statutory language is frequently ambiguous and Parliament cannot foresee every situation, interpretation gives judges real influence over how laws operate in practice. Several established approaches guide the task.
| Approach | Description |
|---|---|
| Literal rule | Words are given their plain, ordinary, dictionary meaning, even if the result is harsh. |
| Golden rule | Where the literal meaning would produce an absurd or repugnant result, a secondary meaning may be adopted. |
| Mischief rule | The court asks what problem ("mischief") Parliament intended the statute to remedy and reads the words to suppress it. |
| Purposive approach | The court interprets the law in light of Parliament's broader purpose. |
The purposive approach has become increasingly dominant, especially since the Human Rights Act 1998, and it gives judges considerable discretion. Supporters argue it fulfils Parliament's true intention; critics argue it lets judges read meanings into legislation that Parliament never put there. A useful example of the interpretive power in action is Pepper v Hart (1993), in which the House of Lords ruled that, where legislation is ambiguous, courts may consult Hansard (the official record of parliamentary debates) to clarify Parliament's intention — a reminder that choosing how to read a statute is itself a constitutionally significant act. The deeper point for evaluation is that interpretation is never wholly mechanical: by selecting an approach and a meaning, judges effectively determine a statute's practical reach, which is one reason why critics describe the purposive method as a route to quasi-legislative power and defenders describe it as the faithful execution of Parliament's true intent.
Section 3 of the HRA requires courts to read and give effect to all legislation, "so far as it is possible to do so", in a way that is compatible with Convention rights. This is a remarkably strong tool: it allows judges to "read down" statutory words, or even read words into a statute, to make it rights-compatible.
Example: In Ghaidan v Godin-Mendoza (2004), the House of Lords used section 3 to interpret the Rent Act 1977, which gave succession rights to a survivor who had lived with the tenant "as his or her wife or husband", as if it read "as if they were his or her wife or husband", thereby extending those rights to a surviving same-sex partner. The statute was effectively reshaped without a single word being formally amended.
The key debate is whether section 3 hands judges too much power to rewrite legislation, or whether it simply ensures that Parliament's overarching intention — expressed in the HRA itself — to legislate compatibly with human rights is honoured. The courts have set a limit: they will not adopt an interpretation that goes "against the grain" of the legislation or that requires choices better left to Parliament. That limit is what separates section 3 (reshaping) from section 4 (declaring).
Where a statute simply cannot be read compatibly with Convention rights, even using section 3, the higher courts may issue a declaration of incompatibility under section 4. This is the pivotal limit on judicial power. A declaration of incompatibility:
In practice, Parliament has amended the law in response to almost every declaration that has become final, which shows the mechanism exerts strong political pressure despite carrying no legal force. This is the design the drafters of the HRA deliberately chose: meaningful judicial protection of rights without surrendering Parliament's supremacy. Since the Act came into force in 2000, only a few dozen declarations have been made, and most have led to legislative change — confirming that the "weak" remedy is, in political reality, surprisingly effective.
| Case | Year | Issue | Outcome |
|---|---|---|---|
| A v Secretary of State (Belmarsh) | 2004 | Indefinite detention of foreign terror suspects | Declaration issued; replaced by control orders (Prevention of Terrorism Act 2005) |
| R (Steinfeld) v Secretary of State | 2018 | Opposite-sex couples excluded from civil partnerships | Declaration issued; Parliament extended civil partnerships |
A point often overlooked is that the courts can strike something down — just not an Act of Parliament. They may invalidate secondary (delegated) legislation — the statutory instruments, regulations, and orders that ministers make under powers granted to them by a "parent" Act. If a minister makes a regulation that goes beyond the powers the parent Act conferred, the regulation is ultra vires (beyond powers) and the courts will quash it. This is fully consistent with parliamentary sovereignty: the courts are enforcing the limits Parliament itself set when it delegated the power.
This matters because modern government relies heavily on delegated legislation, and so much law is now made by ministerial order that judicial policing of vires is a significant constitutional check. The concern is sharpened by so-called Henry VIII powers — provisions in a parent Act that allow ministers to amend or repeal primary legislation by statutory instrument, with limited parliamentary scrutiny. Critics across the political spectrum warn that Henry VIII clauses shift law-making from Parliament to the executive, weakening the very sovereignty the doctrine is supposed to protect. The judiciary's willingness to construe such powers narrowly, and to insist that fundamental rights cannot be overridden by general or ambiguous wording (the principle of legality), is an important way the courts defend Parliament's role against executive encroachment. The lesson for evaluation is that the "courts cannot strike down legislation" rule applies only to primary legislation; with secondary legislation the relationship looks quite different, and the judiciary is markedly more powerful.
It is an over-simplification to say judges only apply law and never make it. Through the common law — judge-made law developed case by case under the doctrine of precedent — the judiciary genuinely shapes whole areas of contract, tort, and criminal liability that originate in no statute. When the Supreme Court decides a novel common-law point, it is making law for the future, and lower courts are bound to follow. The orthodox declaratory theory holds that judges merely discover and declare what the law has always been, but most modern commentators accept that this is a polite fiction in hard cases, where the law is genuinely uncertain and the judges' choice settles it. This creative function sits alongside, but never above, statute: where Parliament has legislated clearly, judges must give effect to the statute even if they would have developed the common law differently. The relationship is therefore layered — the judiciary is at its most creative in the common law, more constrained when interpreting statute, and most constrained of all when confronting an Act that breaches rights, where it can only declare incompatibility.
The relationship runs in both directions: just as the courts interpret Parliament's statutes, Parliament scrutinises the judiciary — though carefully, so as not to compromise judicial independence. Senior judges, including the Lord Chief Justice and the President of the Supreme Court, give evidence to parliamentary committees such as the House of Lords Constitution Committee and the Commons Justice Committee, explaining the operation of the justice system, commenting on the resourcing of the courts, and flagging concerns about proposed legislation. The Lord Chief Justice also makes an annual written report to Parliament.
This dialogue is constrained by convention. Judges are expected to comment on the administration of justice and the practical workability of legislation, but not to enter party-political controversy or to criticise the policy merits of laws they may later have to apply. Equally, the sub judice rule restrains MPs and peers from commenting on cases that are before the courts. The result is a guarded, mutually respectful relationship in which each branch acknowledges the other's legitimate sphere — a practical expression of the separation of powers that the Constitutional Reform Act 2005 sharpened by removing the Law Lords from the legislature.
The relationship between sovereignty and the rule of law is among the most contested questions in UK constitutional law, and it generates excellent evaluative material.
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