You are viewing a free preview of this lesson.
Subscribe to unlock all 10 lessons in this course and every other course on LearningBro.
This lesson examines the landmark cases that have defined the role of the judiciary in UK politics. For Edexcel A-Level Politics, Component 2 (UK Government, Section A), a secure command of key judicial decisions is indispensable, because in Section A you face a 30-mark source-based question and a 30-mark essay in which accurate, well-deployed case examples are the surest route to the higher mark bands. These cases are not simply illustrations to be memorised: each one crystallises a constitutional principle — the limits of prerogative power, the supremacy (or otherwise) of statute, the protection of rights against the state — and each reveals the recurring tension between the judiciary, Parliament, and the executive that examiners reward you for analysing. The skill the specification tests is not recall of facts but the ability to use cases as evidence for an argument about how much power the judiciary really has.
In the UK's uncodified constitution there is no single document that defines the powers and limits of each branch of the state. Much of the constitutional framework is therefore established and clarified through case law — the accumulated decisions of senior judges in individual disputes. When the Supreme Court rules on whether a prerogative power is justiciable, or whether a statute can be read compatibly with rights, it is not merely settling a private quarrel; it is filling in the constitution itself.
Landmark cases matter because they:
Exam Tip: Examiners reward candidates who use a case to prove a point about judicial power, not those who narrate the facts. For every case below, hold in mind the single analytical claim it supports — and the limit on judicial power it also reveals.
The cases that follow are grouped not chronologically but by the constitutional theme they best illustrate, because that is how a Top-band essay deploys them. A vital habit for this topic is to remember that almost every case cuts both ways: a ruling that checks the executive is also, on inspection, evidence of how constrained the judiciary remains, since it can usually do no more than declare, disapply within EU law that no longer applies, or quash a single decision while parliamentary sovereignty stands untouched.
After the 2016 EU referendum, the government argued that it could use the royal prerogative — the residual powers of the Crown exercised by ministers — to trigger Article 50 of the Treaty on European Union (the formal mechanism for leaving the EU) without an Act of Parliament. Gina Miller, a businesswoman and campaigner, challenged this. The High Court ruled in November 2016 that prerogative power alone was insufficient, and the Supreme Court upheld that ruling by 8-3 in January 2017.
The majority reasoned that the European Communities Act 1972 had created a new source of domestic law and a body of rights enjoyed by UK citizens; triggering Article 50 would inevitably strip those statutory rights away; and only Parliament, not the executive, can authorise the removal of rights that Parliament itself created.
| Element | Detail |
|---|---|
| Constitutional principle | The executive cannot use prerogative power to nullify rights granted by statute. |
| Outcome | Parliament passed the European Union (Notification of Withdrawal) Act 2017, authorising the Prime Minister to trigger Article 50. |
| Limit revealed | The Court did not stop Brexit; it merely insisted on the correct constitutional route. Parliament obliged within weeks. |
The case is the modern textbook illustration of parliamentary sovereignty operating against the executive: the courts protected Parliament's exclusive law-making authority. It is worth stressing that Miller I was, in one sense, a pro-Parliament decision rather than an anti-government one — the Court was insisting that a major constitutional change be authorised by the elected legislature, not pushed through by ministerial fiat. This is why characterising it as judges "blocking Brexit" is inaccurate: the ruling determined who could begin withdrawal, not whether it should happen, and Parliament duly authorised it within weeks. The case also provoked the Daily Mail's notorious "Enemies of the People" front page attacking the three High Court judges — the defining recent example of press pressure on the judiciary, and a reminder that high-profile rulings expose judges to political and media hostility that the formal protections of independence cannot fully counter.
In August 2019, Prime Minister Boris Johnson advised the Queen to prorogue (suspend) Parliament for five weeks, from 9 September to 14 October, at a critical point in the Brexit timetable. Critics argued the purpose was to prevent parliamentary scrutiny of the government's approach. Gina Miller challenged the decision in England and Joanna Cherry MP brought a parallel challenge in Scotland; the cases were heard together.
The Supreme Court ruled unanimously (11-0), sitting as a panel of all eleven available justices, that the prorogation was unlawful, void, and of no effect, so that Parliament had never in law been prorogued. Giving the judgment, Lady Hale held that a prorogation will be unlawful if it has the effect of frustrating or preventing, without reasonable justification, Parliament's ability to carry out its constitutional functions, and that the courts could rule on (i.e. the matter was justiciable) the lawfulness of the advice given to the monarch.
| Element | Detail |
|---|---|
| Constitutional principle | Even the prerogative power to prorogue is justiciable and bounded by parliamentary sovereignty and accountability. |
| Significance of unanimity | An 11-0 verdict gave the ruling exceptional constitutional authority and made "rogue court" criticism harder to sustain. |
| Backlash | Fuelled accusations of judicial overreach and helped prompt the Independent Review of Administrative Law (2020-21). |
Miller II is the high-water mark of judicial willingness to police the executive, which is exactly why it is also the case most often cited against the judiciary, as evidence that judges have strayed into political territory. A sophisticated answer uses it on both sides of the "too powerful" debate.
The government used prerogative power to ban trade union membership at Government Communications Headquarters (GCHQ) without consulting the unions. The House of Lords allowed the ban on national-security grounds, but in doing so established two principles of lasting importance: first, that the exercise of prerogative power is in principle reviewable by the courts and not automatically immune simply because it derives from the Crown; and second, the classic threefold framework for judicial review of illegality, irrationality, and procedural impropriety, articulated by Lord Diplock.
The three Diplock grounds remain the organising structure of judicial review to this day. Illegality means the decision-maker misunderstood or exceeded their legal powers — acted ultra vires. Irrationality (or Wednesbury unreasonableness) means the decision was so unreasonable that no reasonable decision-maker could have reached it. Procedural impropriety means the decision-maker failed to follow a fair procedure or breached the rules of natural justice. A fourth ground, proportionality, has since grown in importance, especially under the Human Rights Act, asking whether the action went no further than necessary to achieve a legitimate aim. GCHQ is therefore the foundational case that made decisions like Miller II conceptually possible: by bringing the prerogative within the supervisory jurisdiction of the courts, it vastly widened the executive's exposure to legal challenge — even though, on its own facts, the government won.
If GCHQ widened the scope of review, M v Home Office established that ministers must actually obey the courts. During a deportation case, the Home Secretary, Kenneth Baker, breached an undertaking given to a High Court judge and allowed an asylum seeker, "M", to be removed from the UK contrary to a court order. The House of Lords held that the Home Secretary could be found in contempt of court — the first time a Crown minister had been so held. Although the finding was substituted against the office of Home Secretary rather than against Baker personally, the principle was momentous: a government minister is subject to the orders of the courts like any other person. As the Law Lords recognised, any contrary rule would mean the executive obeyed the law "as a matter of grace and not as a matter of necessity", reversing the constitutional settlement reached after the seventeenth-century struggles between Crown and Parliament. M v Home Office is the case that gives judicial review its teeth, since a remedy a minister could simply ignore would be worthless.
Although the modern landmark cases cluster in the Human Rights Act era, the principle they enforce is centuries old. In Entick v Carrington (1765), the courts held that the King's messengers had acted unlawfully in ransacking the home of the writer John Entick under a general warrant, because no statute or common-law rule authorised the search. Lord Camden's ruling established that the state may only do what the law positively permits — the citizen is free unless the law restrains them, but the government is restrained unless the law empowers it. This is the rule-of-law seed from which judicial review grew: in Miller, Belmarsh, and Rwanda the courts were applying, in modern form, the same insistence that public power must rest on legal authority. Citing Entick shows examiners that you understand the continuity of the principle, not just the recent flashpoints.
The Merchant Shipping Act 1988 required fishing vessels registered in the UK to be majority British-owned, in order to prevent Spanish trawlers "quota-hopping". Spanish fishermen argued this breached EU law on freedom of establishment. Following a reference to the European Court of Justice, the House of Lords disapplied the relevant provisions of the 1988 Act, holding that domestic legislation conflicting with directly effective EU law had to be set aside while the UK remained in the EU.
This was constitutionally startling because an Act of Parliament was, in effect, overridden — something that appeared to contradict the Diceyan account of parliamentary sovereignty. The orthodox reconciliation is that Parliament had itself willed this outcome through the European Communities Act 1972, so the courts were giving effect to Parliament's own choice rather than defying it.
Important: Factortame must now be handled as a historical case. Following the UK's withdrawal from the EU and the repeal of the European Communities Act 1972, EU law is no longer supreme over UK statute in this way. Cite Factortame to show that the courts were willing to disapply legislation under EU law, but be explicit that this avenue no longer exists post-Brexit. Misrepresenting it as current law is a serious factual error.
The enduring lesson is about the elasticity of parliamentary sovereignty: Factortame showed that sovereignty could accommodate the temporary supremacy of an external legal order, while Brexit showed that Parliament could reclaim that supremacy by legislating to leave. Both directions confirm, rather than deny, that Parliament remained the ultimate source of authority.
After the 9/11 attacks, the Anti-terrorism, Crime and Security Act 2001 permitted the indefinite detention without trial of foreign nationals suspected of terrorism, who were held in HMP Belmarsh. To do this, the government had derogated from (opted out of) Article 5 of the ECHR (the right to liberty). The House of Lords, sitting as a panel of nine, ruled 8-1 that the detention scheme was incompatible with Article 5 (liberty) and Article 14 (non-discrimination).
The majority held that the scheme was discriminatory, because it applied only to foreign nationals when British terror suspects posed a comparable threat, and disproportionate, because less restrictive measures were available. Lord Hoffmann delivered one of the most quoted judicial statements in modern British law:
"The real threat to the life of the nation, in the sense of a people living in accordance with its traditional laws and political values, comes not from terrorism but from laws such as these."
The case is doubly important. It demonstrates judicial courage on national security, an area where courts have traditionally deferred to ministers, and it demonstrates the limit on judicial power, because the Law Lords could issue only a declaration of incompatibility under section 4 of the Human Rights Act 1998. They could not abolish the scheme; the detention remained lawful until the government chose to act. In practice the government replaced indefinite detention with control orders under the Prevention of Terrorism Act 2005 — confirming that a declaration exerts powerful political pressure despite carrying no legal force. Belmarsh is therefore the single best case for capturing the paradox at the heart of this topic: it is simultaneously the clearest evidence that judges will stand up to the government on the gravest questions of state, and the clearest evidence that, when they do, their power stops at a declaration that the elected branches are free to honour, delay, or ignore. A candidate who can hold both halves of that thought together has grasped what the specification is really asking.
The government argued that evidence obtained through torture by foreign agencies could be relied on in UK legal proceedings, provided UK officials had not themselves participated in the torture. The House of Lords unanimously rejected this, holding that evidence obtained by torture is inadmissible in any UK court, whoever carried it out. Lord Bingham grounded the ruling in the common law itself, describing third-party torture evidence as unreliable, unfair, and "offensive to ordinary standards of humanity and decency". The case reaffirmed the absolute prohibition on torture and showed the judiciary setting moral and legal boundaries on executive conduct even under acute security pressure — a useful counterpoint to the claim that judges always defer on security.
Subscribe to continue reading
Get full access to this lesson and all 10 lessons in this course.