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This lesson examines the relationship between the judiciary and the executive in UK politics. For Edexcel A-Level Politics, Component 2 (UK Government, Section A), this is the relationship that generates the most charged contemporary debate, because it is here — in judicial review of ministers, prerogative powers, deportation, and detention — that the courts most visibly confront the government of the day. Where the judiciary-Parliament relationship turns on the abstract limit of parliamentary sovereignty, the judiciary-executive relationship is concrete and adversarial: a citizen challenges a minister's decision, and the court must decide whether the minister acted lawfully. The growth of judicial review since the 1960s, the willingness of the courts to police even the royal prerogative, and the government's responses — from criticism of "activist" judges to legislation curbing review — make this the natural home of the "is the judiciary too powerful?" question that Section A so often asks.
The executive — the Prime Minister, Cabinet, and government departments — wields enormous power in the UK system. It proposes and implements legislation, manages public services, conducts foreign policy, commands the armed forces, and exercises the royal prerogative (powers historically belonging to the Crown and now exercised by ministers). Yet all of this power is conditional: the executive must act within the law. The rule of law requires that every governmental action rest on a legal basis — either statute or prerogative. Where the government acts without legal authority, its action is ultra vires (beyond its powers) and the courts may quash it.
Key Term: The executive must always act within its legal powers. Judicial review is the mechanism by which the courts enforce this requirement, holding ministers to account between elections.
This is a crucial constitutional safeguard precisely because the UK executive is so dominant. In a system where the government usually commands a Commons majority and can shape the legislative agenda, Parliament's ability to restrain ministers day-to-day is limited. The courts therefore provide a legal check that complements the political check of Parliament — and unlike a parliamentary majority, a court cannot be whipped. This is one reason the judiciary's role has grown in prominence: as the so-called "elective dictatorship" thesis suggests, a government with a working majority faces relatively weak parliamentary constraint, so the legal accountability supplied by judicial review has become correspondingly more important. The point should not be overstated — Parliament retains formidable scrutiny tools and the ultimate power to legislate — but it helps explain why citizens, pressure groups, and opposition politicians increasingly turn to the courts to challenge executive action that they cannot defeat in the Commons.
Judicial review is the primary mechanism by which the judiciary checks the executive. It is essential to grasp at the outset what judicial review does not do: it does not ask whether a decision was wise, popular, or good policy. It asks only whether the decision-maker stayed within their legal powers, acted rationally, and followed a fair procedure. Judges police the boundaries of power, not the merits of policy. The grounds, set out by Lord Diplock in the GCHQ case (1985), are:
| Ground | Meaning |
|---|---|
| Illegality | The decision-maker lacked legal power to act, or misunderstood and misapplied the law (ultra vires). |
| Irrationality | The decision was so unreasonable that no reasonable decision-maker could have reached it (Wednesbury unreasonableness). |
| Procedural impropriety | The decision-maker failed to follow a fair procedure, e.g. by denying affected parties a hearing. |
| Proportionality | (Especially in HRA cases) the action went further than necessary to achieve a legitimate aim. |
Example: In R (UNISON) v Lord Chancellor (2017), the Supreme Court held that the Lord Chancellor's decision to impose employment tribunal fees was unlawful because it effectively denied access to justice — a constitutional right. Note that the Court struck down a ministerial decision and statutory instrument, which it is entitled to do, not an Act of Parliament, which it is not.
Judicial review has grown enormously since the 1960s, as judges became increasingly willing to insist that public power be exercised lawfully and fairly across immigration, prisons, environmental policy, welfare, and constitutional questions. This expansion is the single clearest piece of evidence for the argument that the judiciary's role has grown — though, as ever, the expansion concerns legality, not policy.
It also matters that judicial review is hedged with limits that the courts themselves enforce, which counters the impression of an unconstrained judiciary. A claimant must have standing ("sufficient interest" in the matter), must generally bring the claim promptly and in any event within three months, and must first obtain permission from the court to proceed to a full hearing — a filter that screens out unarguable claims. The remedies are discretionary: even where a claimant wins, the court decides what remedy, if any, to grant, and may decline relief where it would serve no useful purpose. Finally, judicial review is not an appeal: the court does not substitute its own decision for the minister's or retry the facts; if it finds a decision unlawful, it normally sends the matter back for the decision-maker to take again, lawfully. A minister who loses a judicial review can therefore often reach the same outcome by following a correct procedure — a powerful reminder that the courts control the legality of the process, not the substance of the policy.
The royal prerogative refers to powers that the Crown — in practice the government — exercises without fresh parliamentary authorisation. They include declaring war and deploying the armed forces, negotiating and ratifying treaties, granting pardons, appointing ministers, and proroguing Parliament. These are substantial powers exercised without a specific Act behind them, which is precisely why their reviewability matters so much: if the prerogative were wholly beyond the courts, a large and constitutionally significant area of executive action would be immune from legal challenge. Historically these powers were considered non-justiciable: the courts would not examine how they were exercised, treating them as beyond their reach simply because they derived from the Crown.
The GCHQ case (1985) transformed this. The government had used prerogative power to ban trade unions at Government Communications Headquarters without consultation. The House of Lords allowed the ban on national-security grounds but established the landmark principle that the exercise of prerogative power is, in principle, reviewable by the courts. This brought a vast swathe of executive action within the supervisory jurisdiction of the judiciary for the first time. Before GCHQ, the orthodoxy was that prerogative powers were simply beyond the courts because they flowed from the Crown; after GCHQ, the question became not whether a power derived from the prerogative but whether its subject-matter was suitable for judicial determination. That shift — from the source of a power to its justiciability — is the conceptual foundation on which Miller I and Miller II were later built, and it is why GCHQ, despite the government winning on the facts, is the single most important case for understanding the modern reach of review over the executive.
The Miller cases then pushed the principle to its limits:
Together these cases dramatically expanded judicial oversight of the prerogative — and provoked the sharpest accusations of judicial overreach in modern times, since the courts had reached into the most politically sensitive territory imaginable.
It is worth distinguishing what the Miller cases did and did not establish, because careless summaries cause factual errors. Miller II did not hold that prorogation is always reviewable in its political wisdom; it held that prorogation becomes unlawful only where it frustrates Parliament's constitutional functions without reasonable justification, and that the government had offered no such justification for a five-week suspension at a critical moment. The Court was careful to frame the test in terms of legal limits on a power, not the merits of using it. Critics nonetheless argued that the very existence of such a test drew the judiciary into adjudicating an essentially political dispute between Parliament and the executive, and that the courts had effectively created a new legal limit on a long-standing prerogative. Defenders countered that an unconstrained power to silence Parliament indefinitely would be incompatible with both parliamentary sovereignty and accountable government, so the courts were protecting the constitution, not colonising politics. This disagreement is the live wire of the whole topic, and a candidate who can articulate both readings of Miller II — overreach versus essential check — is well placed for the highest marks.
Under the Human Rights Act 1998, the judiciary checks the executive in three ways. By section 6, it is unlawful for any public authority — including ministers, the police, and government departments — to act incompatibly with Convention rights, so the courts can declare executive actions unlawful directly. By section 3, the courts interpret legislation compatibly with Convention rights so far as possible, narrowing the scope ministers have to act adversely to rights. By section 4, where primary legislation cannot be read compatibly, the higher courts may issue a declaration of incompatibility.
Example: In the Belmarsh case (2004), the House of Lords ruled that the executive's scheme of indefinitely detaining foreign terror suspects was incompatible with Articles 5 and 14 of the ECHR. The courts could not abolish the scheme, but the declaration forced the government to replace it with control orders — a vivid demonstration of judicial pressure on the executive even in national security.
The cases below recur throughout Section A. Hold in mind, for each, both the check it represents and the limit it reveals.
| Case | Issue | Decision | Significance |
|---|---|---|---|
| GCHQ (1985) | Could prerogative power ban unions at GCHQ? | Government won on national-security grounds, but prerogative held reviewable in principle | Opened the prerogative to judicial review |
| M v Home Office (1993) | Could a minister be held in contempt for breaching a court order? | Yes — against the office of Home Secretary | Ministers must obey the courts; review has teeth |
| Miller I (2017) | Could the government trigger Article 50 by prerogative? | No (8-3) — only Parliament could remove statutory rights | Executive cannot use prerogative to override statute |
| Miller II (2019) | Was the advice to prorogue Parliament lawful? | No (11-0) — unlawful, void, of no effect | Even prorogation is justiciable |
| Belmarsh (2004) | Was indefinite detention of foreign suspects lawful? | Incompatible with the ECHR (declaration) | Courts challenge the executive on security |
| AAA / Rwanda (2023) | Was Rwanda a safe country for removals? | No — unanimous; risk of refoulement | Executive then used Parliament to override the ruling |
The Rwanda case is the indispensable bookend: the Supreme Court found unanimously that Rwanda was not a safe third country, and the government responded with the Safety of Rwanda (Asylum and Immigration) Act 2024, declaring Rwanda safe by statute. It shows the executive's ultimate trump card — using its parliamentary majority to legislate around an adverse ruling — and confirms that, on any unwelcome judgment, the elected branches can have the final word.
When the executive loses in court, it has a graduated menu of responses, ranging from full compliance to attempts to curb the courts. Which response a government chooses is itself revealing about the health of the relationship: routine acceptance signals respect for the rule of law, whereas a pattern of legislating around rulings and attacking judges signals a more confrontational posture. The options below are arranged roughly from the most constitutionally orthodox to the most contested.
| Response | Example |
|---|---|
| Accept and comply | The government accepted Miller I and passed the EU (Notification of Withdrawal) Act 2017. |
| Change the law | After the Rwanda ruling, Parliament passed the Safety of Rwanda Act 2024. |
| Criticise the judges | Home Secretaries have publicly attacked judges over immigration and sentencing decisions. |
| Curb judicial review | The Judicial Review and Courts Act 2022 introduced suspended and prospective-only quashing orders. |
| Propose constitutional reform | Proposals to replace the HRA with a British Bill of Rights would narrow judges' scope to challenge ministers. |
The most constitutionally significant of these is the Judicial Review and Courts Act 2022, which followed the government's Independent Review of Administrative Law (2020-21), itself prompted by the run of defeats culminating in Miller II. The Act introduced suspended quashing orders (allowing a court to delay the effect of quashing a decision) and prospective-only quashing orders (limiting a quashing to future effect, so past actions under the unlawful decision stand). Supporters present these as sensible flexibility; critics argue they weaken the remedy's bite and were designed to discipline a judiciary the executive found inconvenient. Either way, the Act illustrates a key constitutional truth: because the executive can usually command a parliamentary majority, it can reshape the law of judicial review itself, so the courts' supervisory power exists only on terms a sovereign Parliament permits.
Exam Tip: The 2022 Act and the "judicial overreach" debate are the freshest material for this topic. The analytical point is the distinction between legitimately reforming the law of judicial review (constitutionally proper) and intimidating or punishing the courts for unwelcome rulings (constitutionally improper). Strong answers hold that distinction carefully.
The run of high-profile defeats for the executive between 2016 and 2019 — the first Miller case, a series of immigration and welfare rulings, and above all Miller II — generated a sustained political backlash that is essential context for this relationship. Some ministers and commentators argued that the judiciary had strayed beyond its proper role into political territory, that judges had become "activist", and that the scope of judicial review needed to be curtailed to restore the proper balance between elected and unelected branches.
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