Public Law

Public law is the law of public power: where it comes from, who may exercise it, and what happens when it is exercised badly. The United Kingdom does all of this without a codified constitution: the rules are scattered across Acts of Parliament, judicial decisions, political practices that bind without being enforceable, and the historic powers of the Crown. The whole subject is one question asked in many guises — by what authority does this body do this thing? — with its companion: who holds the body to account if the answer is "none"?

The discipline the module trains is precision about power: identify a power's source (statute, or something older), its legal limits, and the mechanism — political or legal — that checks its exercise. It is emphatically not a module about whether any particular government is good or bad; the analysis must work identically whoever is in office, and that is rather the point.

The constitution and its sources

The UK constitution is uncodified, not absent; its rules live in four places. Statute is the highest source, and some statutes matter more than others: Thoburn introduced the idea of a constitutional statute, one that resists implied repeal, yielding only to express words. Common law supplies much of the rest: Entick v Carrington is the emblem — the officers who searched a private house could show no legal authority, so their entry was mere trespass. Conventions are the constitution's political rules — the monarch assents to Bills, ministers answer to Parliament — obeyed in practice, enforceable by no court. And the royal prerogative is the residue of the Crown's historic power, exercised today by ministers.

Parliamentary sovereignty

The organising doctrine. Parliamentary sovereignty means Parliament may make or unmake any law, and no court may set an Act aside; its corollary is that no Parliament can bind its successors. During EU membership, Factortame saw an Act disapplied for conflicting with Community law — on the footing that an earlier Parliament had itself so instructed the courts. Membership has ended; the demonstration has not. And in Jackson, a challenge to legislation passed under the Parliament Acts, some judges said — obiter, but deliberately — that sovereignty is a common law construct whose absoluteness might one day be qualified in an extreme case.

The rule of law

The second master principle. In its formal conception, the rule of law requires that power be exercised under clear, prospective, general rules applied by independent courts — it says nothing about what the rules contain. Substantive conceptions add content — fundamental rights, access to justice — and the courts increasingly treat some of it as constitutional. UNISON quashed employment tribunal fees because they impeded the common law right of access to justice; M v Home Office made "no one is above the law" operational — injunctions run against ministers, who can be in contempt of court. The same instinct yields the principle of legality: general statutory words are presumed not to override fundamental rights — a Parliament wanting to must say so squarely and take the political cost.

Separation of powers

The UK's separation of powers is real but partial. The executive sits inside the legislature and usually commands its majority, which is why the constitution leans on the two robust checks: parliamentary scrutiny and judicial independence, the latter reinforced by the Constitutional Reform Act 2005. The doctrine still bites. In ex parte Fire Brigades Union, a minister who preferred his own compensation scheme to one Parliament had enacted but not yet commenced could not use the prerogative to frustrate the statute: what Parliament has enacted, the executive may not work around.

The royal prerogative

The prerogative covers powers with no statutory parent — making and unmaking treaties, deploying the armed forces, prorogation of Parliament. Three propositions domesticate it. It cannot be enlarged: the Case of Proclamations held that the Crown cannot change the law by decree and has only the prerogative the law allows. Statute beats it: under Attorney General v De Keyser's Royal Hotel, where Parliament has covered the ground, the government must use the statute rather than the prerogative beneath it. And its exercise is open to challenge: Council of Civil Service Unions v Minister for the Civil Service — the GCHQ case — held that reviewability turns on a power's subject matter, not its source.

The two Miller cases apply all three propositions. In Miller (No 1), ministers could not use the treaty prerogative to trigger the Article 50 withdrawal process, because withdrawal would strip out rights that an Act of Parliament had made part of domestic law — only an Act can do that, so a statute was needed. In Miller (No 2) — the prorogation case — the court held the question justiciable — the existence and limits of a prerogative power are always questions of law — and the prorogation unlawful, because it frustrated Parliament's ability to legislate and hold the government to account, without reasonable justification. Miller (No 1) asks which organ of state may change domestic law; Miller (No 2) asks whether the limits of a prerogative power can be policed by courts at all. Conflating them loses marks.

Parliament and executive accountability

Most control of government is political, not legal. Ministers answer to Parliament through the conventions of ministerial responsibility, through questions and select committees, and ultimately through the confidence of the Commons. The courts are a backstop — though Miller (No 2) treated parliamentary accountability as a principle law may protect. In any scenario, ask which mechanism is doing the work: a breached convention invites political consequences; a crossed legal limit invites a court.

Judicial review

Judicial review is the courts' supervisory jurisdiction over public decision-making, and supervisory is the operative word: the question is never whether the decision was right, only whether it was lawfully made. The classic grounds carry the GCHQ grouping. Illegality: the decision-maker misunderstood the law or acted ultra vires. Irrationality: a decision so unreasonable that no reasonable authority could have reached it, the standard named for Associated Provincial Picture Houses v Wednesbury Corporation. Procedural impropriety: unfair procedure or bias, revived for the modern administrative state by Ridge v Baldwin. Fairness can also hold a public body to a clear promise or settled practice — a legitimate expectation. Where Convention rights are in play, review sharpens into proportionality — structured into four questions in Bank Mellat (No 2) and, as Daly made explicit, more intense than rationality review.

A claimant needs standing — sufficient interest — and remedies are discretionary: quashing, mandatory and prohibiting orders, declarations. When Parliament tries to shut the courts out with an ouster clause, the courts read it to death. Anisminic treated a determination flawed by error of law as a nullity, which a clause protecting "determinations" does not reach; Privacy International carried the approach forward, with dicta doubting whether any words could wholly exclude review. Whether that is interpretation or defiance is section 3's problem.

The Human Rights Act and devolution

The Human Rights Act 1998 gives domestic effect to Convention rights through four load-bearing sections. Under section 2, courts must take the Strasbourg case law into account — account, not obedience. Under section 3, legislation must be read and given effect, so far as possible, compatibly with Convention rights — a power going well beyond resolving ambiguity, as Ghaidan v Godin-Mendoza shows, but stops short of anything against the grain of the statute. Where a compatible reading is impossible, section 4 lets the higher courts make a declaration of incompatibility — which changes nothing legally: the Act stays in force, and the response belongs to Parliament. And section 6 makes it unlawful for public authorities to act incompatibly with Convention rights. Finally, devolution: the Scottish Parliament, the Senedd and the Northern Ireland Assembly are creatures of statute with limited competence, so — unlike Westminster's — their legislation can be struck down as outside its limits. The Sewel convention, under which Westminster does not normally legislate on devolved matters without consent, remains a convention, with everything that word implies.

These are the places where the law is unsettled, criticised, or split — which makes them exactly where essays and first-class problem answers are won.

• Is sovereignty actually absolute? The orthodox account says yes. The Jackson obiter suggests some judges doubt it would survive an extreme case — abolition of judicial review, say. Common law constitutionalists argue that a doctrine the courts recognised, the courts could qualify; the reply is that this relocates supremacy to judges nobody elected. And Factortame cuts both ways: sovereignty qualified by membership, or a sovereign Parliament telling the courts what to do until it said otherwise — as eventually it did.
• Constitutional statutes. Thoburn's hierarchy is attractive and troubling at once: who decides which statutes are constitutional, by what criteria, and how is a common law hierarchy of Acts compatible with the sovereignty of the Parliament that enacted all of them equally? Later cases have used the category without giving it firm edges.
• Ouster clauses. Anisminic and Privacy International read exclusionary words almost to vanishing point. Is that loyal interpretation — a presumption Parliament never intends to abandon the rule of law — or disobedience dressed as construction? This is the module's deepest fault line: sovereignty and the rule of law, pointed directly at each other.
• Justiciability after Miller (No 2). The court said the limits of a prerogative power are always a legal question; critics answer that a standard like "reasonable justification" draws judges into terrain the constitution polices politically; defenders say the court enforced existing principle against an executive act that would have disabled it. An argument about institutional roles, not policy — conduct it that way.
• Rationality or proportionality? Daly insists they differ; Bank Mellat (No 2) gives proportionality its structure. Whether proportionality should replace Wednesbury as a general ground of domestic review is a question the courts have repeatedly flagged and deliberately left open — perfect essay territory.
• How substantive is the rule of law? UNISON poured real content — access to justice — into it. Formalists ask where such content comes from and where it stops; substantivists answer that a purely formal rule of law would bless a tyranny of impeccably drafted statutes.
• Interpretation or amendment? Ghaidan lets section 3 carry readings the words would not naturally bear. At what point does "reading compatibly" become legislating? And if declarations of incompatibility are almost always acted on in practice, is the formal preservation of sovereignty real, or a constitutional politeness?

Not a case list — a working set. Public law rewards attaching the right authority to the right proposition, so learn each of these as the anchor of one idea.

• Entick v Carrington — state power needs positive legal authority; the foundation stone of legality.
• Case of Proclamations — the Crown cannot change the law or create offences by proclamation.
• Attorney General v De Keyser's Royal Hotel — where statute covers the ground, the prerogative cannot be used to bypass it.
• Council of Civil Service Unions v Minister for the Civil Service — prerogative reviewable by subject matter; the classic grouping of the grounds.
• Miller (No 1) — triggering withdrawal from the EU needed an Act of Parliament: the prerogative cannot change domestic law or remove rights.
• Miller (No 2) — prorogation is justiciable, and unlawful where it frustrates Parliament's constitutional functions without reasonable justification.
• Thoburn v Sunderland City Council — constitutional statutes resist implied repeal.
• Jackson v Attorney General — the Parliament Acts challenge; obiter doubts about the absoluteness of sovereignty.
• Factortame — an Act disapplied while EU membership lasted. Context has moved: the UK has left, but the case keeps its force as evidence of what sovereignty can accommodate when Parliament directs it.
• Associated Provincial Picture Houses v Wednesbury Corporation — the rationality threshold: interference only where no reasonable authority could have so decided.
• Ridge v Baldwin — natural justice revived: a fair hearing before an adverse administrative decision.
• Anisminic — error of law makes a decision a nullity, which an ouster clause does not protect.
• ex parte Fire Brigades Union — a minister cannot use the prerogative to frustrate a scheme Parliament has enacted.
• Ghaidan v Godin-Mendoza — the reach, and the against-the-grain limit, of interpretation under section 3.
• Daly — common law rights plus proportionality; intensity of review varies with what is at stake.
• Bank Mellat (No 2) — the structured four-question proportionality test.
• UNISON v Lord Chancellor — access to justice is a constitutional right; tribunal fees that impeded it were unlawful.
• Privacy International — the Anisminic approach to ousters carried forward, with dicta doubting any total exclusion of review.
• M v Home Office — injunctions and contempt findings run against ministers of the Crown.

Terms that look like English but carry technical loads. When one of these appears dotted-underlined in the text above, tap it for the definition in place.

Convention

A rule of constitutional practice regarded as binding, but enforceable by no court; breach carries political consequences, not legal ones.

Prerogative

The residue of the Crown's historic legal powers, exercised today by ministers. Limited and reviewable by law; incapable of enlargement.

Prorogation

Ending a parliamentary session, suspending sittings and most business until the next opens. Not dissolution, which ends the Parliament itself.

Parliamentary sovereignty

Parliament may make or unmake any law, and no court may set an Act of Parliament aside.

Constitutional statute

A statute fundamental enough to rights or the constitutional order that courts treat it as repealable only by express words (or wording so specific the intention is unmistakable).

Implied repeal

The default rule that a later Act silently overrides an earlier, inconsistent one. Constitutional statutes resist it.

Rule of law

Power exercised under law: clear, prospective, general rules applied by independent courts. How much substantive content the idea carries is contested.

Principle of legality

General statutory words are presumed not to override fundamental rights; Parliament must legislate squarely and take the political cost.

Separation of powers

Distributing state power between legislature, executive and judiciary so no branch is unchecked. Partial in the UK: the executive sits inside the legislature.

Judicial review

The High Court's supervisory jurisdiction over the lawfulness of public decision-making. Lawfulness — never the merits.

Ultra vires

"Beyond the powers": action outside the authority the law confers.

Irrationality

A decision so unreasonable that no reasonable decision-maker could have reached it — Wednesbury unreasonableness. A deliberately high bar.

Procedural impropriety

Failure to follow required procedure or the common law's demands of fairness: a fair hearing, an unbiased decision-maker.

Legitimate expectation

A clear promise or settled practice by a public body which fairness may require it to honour.

Proportionality

A structured test: is the objective important enough, the measure rationally connected to it, no less intrusive alternative available, and a fair balance struck?

Standing

Sufficient interest in the matter — the threshold for bringing a judicial review claim.

Ouster clause

A statutory provision attempting to exclude the courts' review jurisdiction. Read very narrowly indeed.

Justiciability

Whether legal standards exist for a court to answer a question, or it belongs to political judgment alone.

Declaration of incompatibility

A section 4 declaration that legislation conflicts with Convention rights. The legislation stays in force; the response belongs to Parliament.

Devolution

The statutory transfer of legislative and executive power to Scotland, Wales and Northern Ireland — within limits the courts can police, unlike Westminster's.

Openly published, deliberately. If you can answer these without notes, the module's architecture is in place. Each reveal describes what a good answer contains — not a script to memorise.

Ministers already hold the treaty prerogative. Why, in Miller (No 1), was that not enough to start the process of leaving the EU?

The two planes: the prerogative operates internationally, but cannot change domestic law or take away rights domestic law confers — and Parliament had made EU law a source of domestic rights, so triggering withdrawal would inevitably strip them out — which only statute can do. A good answer states the principle, connects it to De Keyser's logic of statute displacing prerogative, and sees that the decision protects parliamentary sovereignty rather than limiting government for its own sake.

In Miller (No 2) the government argued prorogation was high policy, for ministers answerable to Parliament rather than judges. Why could a court decide it anyway — and where does that argument strain?

The justiciability move: the existence and limits of any power are questions of law, so asking whether prorogation exceeded its limits is orthodox judicial work — and the limits were found in parliamentary sovereignty and executive accountability, which the prorogation would disable. A good answer separates that from reviewing the decision's merits, which the court disclaimed. It strains where "reasonable justification" requires evaluative judgment about how much interruption of Parliament is too much; a strong answer concedes the critics' point and keeps the discussion at the level of institutional roles.

A government legislates on a devolved matter without consent, ignoring the Sewel convention. No court will intervene — Miller (No 1) confirms it. So why do governments usually comply, and what would be gained or lost by making conventions enforceable?

The nature of conventions: binding in political practice, enforced by political cost — parliamentary trouble, intergovernmental breakdown, electoral consequence — not by courts, even where a convention is acknowledged in statute. A good answer explains why compliance is nonetheless the norm — the practice serves relationships governments need — then argues codification both ways: enforceability buys certainty and protection against a determined government, at the price of flexibility and of judges refereeing political relationships. Either conclusion is fine; understanding what conventions are for is the point.

Parliament enacts: "Determinations of the Tribunal shall not be questioned in any court." Sovereignty says courts obey statutes. Explain how Anisminic and Privacy International handle such clauses — and whether that is obedience or defiance.

The nullity reasoning: a determination infected by error of law is no determination at all, so a clause protecting "determinations" does not reach it — resting on the presumption that Parliament does not intend to exclude the rule of law without unmistakable words. A good answer runs the argument both ways: loyal interpretation (courts serve Parliament's deeper intent) against defiance in construction's clothing (no drafter could satisfy a court determined not to be satisfied). The best answers name what is really colliding — sovereignty and the rule of law — and say which should yield at the limit, knowing the law has never had to choose.

Why does section 4 of the Human Rights Act exist at all — why not simply let courts strike down incompatible Acts? And does Ghaidan's use of section 3 quietly undermine the answer?

The design: striking down Acts would end parliamentary sovereignty, so the Act splits the difference — section 3 makes courts stretch for a compatible reading, and where none is possible, section 4 hands the problem back to Parliament with the legislation still in force: toothless by design, and the toothlessness is the feature. Then the pressure point: Ghaidan lets section 3 depart from the natural meaning of words, so the further interpretation reaches, the more courts amend statutes in substance while sovereignty is preserved in form — and declarations are usually acted on in practice. A strong answer weighs whether "dialogue" describes this honestly, and concludes either way with the architecture in view.