52-48 to Leave, on rules set by an Act of Parliament, advisory in law and binding in politics. Scotland and Northern Ireland voted Remain - the mandate split by nation from the first morning.
The biggest single constitutional decision since accession in 1973, and the strongest evidence in any sovereignty essay that the political location of sovereignty has moved towards the electorate.
The 52-48 Leave vote on a 72% turnout was political sovereignty exercised directly by the electorate - a decision to reclaim the sovereignty pooled since the European Communities Act 1972, when EU law gained primacy and Factortame (1990) showed a UK Act could be disapplied.
In a sovereignty essay, the referendum is where the legal-versus-political distinction starts doing work.
For four years after June 2016 the result, not ministers, set the policy: Cameron resigned the morning after, May's government inherited an instruction it had not chosen, and both major parties accepted the result as politically binding.
The executive spent the period delivering a decision made above its head - the reverse of executive empowerment.
The referendum was advisory in law - Parliament was sovereign over whether to act on it - but politically binding because both major parties accepted the result. A sovereign Parliament felt unable to use its sovereignty.
That gap between legal power and political reality is the era's paradox in a single episode.
Scotland and Northern Ireland voted Remain while England and Wales voted Leave - the mandate split by nation from the first morning, before any negotiation began.
Every later strain in this column - Sewel, the Internal Market Act, the Irish Sea border - traces back to that split result.
The vote itself produced no litigation - the courts entered the story six months later, when Gina Miller challenged the government's attempt to trigger Article 50 by prerogative.
Useful sequencing point: the referendum set the question, and the Miller cases then decided who answers it.
The vote answered membership and opened everything else: how to leave (Miller 1), on what legal terms (the Withdrawal Acts), what happens to the UK internal market (the IMA), and what happens to Northern Ireland (the Protocol, then Windsor).
One settled question, four new ones - the era's pattern set on day one.
The biggest single constitutional decision since accession in 1973: it ended 47 years of pooled sovereignty and triggered every other row in this grid. Cameron's resignation the next morning showed it had also become a confidence vote on the government.
For essays on where sovereignty sits, the referendum is the strongest evidence that political sovereignty has moved towards the electorate.
The Supreme Court ruled 8-3 that the government could not trigger Article 50 by prerogative alone - an Act of Parliament was required. The same judgement confirmed the Sewel Convention is political, not legally enforceable.
Parliament's role protected, the prerogative cut back, and devolved consent shown to have no legal teeth - three essays' worth of significance in one ruling.
The Supreme Court ruled 8-3 that triggering Article 50 would change UK law - it would set in motion the removal of rights derived from EU law - and only Parliament can change UK law. The prerogative could not do it alone.
The ruling restated the bedrock rule at the era's most pressured moment: sovereignty belongs to Parliament, not to ministers acting in its name.
The government argued the prerogative power covered withdrawal from a treaty; the Court disagreed, and the executive had to legislate instead. A prerogative claim made at the limit of its reach was cut back in public.
Pair with Miller 2 for the era's pattern: the executive pushed twice, the Court stopped it twice.
Parliament's legislative role was protected in the most concrete way possible: the European Union (Notification of Withdrawal) Act 2017 had to be passed before Article 50 could be triggered. The biggest decision of the era went through the Commons because the Court said it must.
The same judgement confirmed the Sewel Convention is political, not legally enforceable - devolved consent to Brexit legislation could be sought, refused, and overridden without legal consequence.
That finding flows straight into the Internal Market Act row, where Westminster did exactly that.
Gina Miller's challenge put the Supreme Court at the centre of the era's biggest political question within six months of the vote - an 8-3 ruling on who controls the constitution's most consequential decision.
The case opened the judicial-power debate that Miller 2 and the codification essays inherit.
The ruling settled the trigger question only: an Act was required, the Act was passed, and every substantive question - the deal, the border, the internal market - remained open.
Narrow but permanent: the limit it set on prerogative power over constitutional change outlives Brexit itself.
Miller 1 defined the limits of prerogative power over constitutional change: where executive action would remove rights created by statute, only statute can authorise it. The 8-3 margin shows the question was genuinely hard.
It earns a place in three essays at once - sovereignty, judiciary, and devolution via the Sewel finding.
Repealed the European Communities Act 1972, converted EU law into retained UK law, and gave ministers Henry VIII powers to amend statutes in adapting it.
The legal core of Brexit - and the executive's biggest quiet gain of the era.
Repealing the European Communities Act 1972 removed the statute that had given EU law primacy in the UK for 47 years - the arrangement under which Factortame disapplied the Merchant Shipping Act 1988. The one true legal constraint on parliamentary sovereignty went by ordinary Act.
That it took only an ordinary statute is itself the sovereignty point: nothing binds Parliament that Parliament cannot unbind.
The Act gave ministers Henry VIII powers - the power to amend statutes by statutory instrument - to adapt the converted body of EU law. Scrutiny of statutory instruments is generally weaker than scrutiny of full Bills.
This is the quiet centre of the executive-empowered column: power returned from Brussels and a large share of it landed in ministers' hands.
The vast delegated powers shifted the detail of the post-Brexit statute book away from Parliament: changes that would once have needed an Act could now be made by ministerial instrument with limited scrutiny.
The paradox to use in essays: the Act that restored Parliament's legal sovereignty simultaneously moved practical law-making towards the executive.
Powers returning from Brussels in devolved areas were retained at Westminster first rather than passing straight to Edinburgh, Cardiff and Belfast - the origin of the power-grab argument that the devolved governments carried into the Internal Market Act fight.
The Act generated no landmark litigation of its own - the era's court battles were over the prerogative (the Millers), not the statute. Its constitutional work was done in the drafting, not the courtroom.
The sovereignty grid runs this same statute through Dicey's three rules - the identical episode answering a different exam question.
The legal mechanics of exit were settled: the ECA repealed, EU law converted into retained UK law, continuity preserved at the moment of departure. The Retained EU Law Act 2023 later finished the job by ending the special status of EU-derived law altogether.
The statute that unwound 47 years of EU law primacy - after it, Factortame-style cases cannot happen for new disputes, because no court can disapply an Act of Parliament against EU law that no longer binds.
In a sovereignty essay this is the legal answer's anchor: cite it with the Retained EU Law Act 2023 as the pair that closed the era.
The Supreme Court ruled unanimously, 11-0, that the five-week prorogation was unlawful because it frustrated Parliament's constitutional functions during the Brexit crisis. Parliament was recalled the next day.
The first ruling on the personal royal prerogative, and the moment the courts stepped deepest into the political arena.
The Court held that the five-week prorogation was unlawful because it frustrated Parliament's constitutional functions at the height of the Brexit crisis - the government cannot use prerogative powers to prevent Parliament doing its job.
Parliamentary sovereignty was the common-law principle the Court reached for, in the absence of any written rule on prorogation.
The prorogation was declared unlawful, void and of no effect - the strongest language available - and the prerogative was cut back for the second time in three years. An executive attempt to govern around Parliament failed completely.
With Miller 1, it shows the era's executive gains came through statute (Henry VIII powers), not through the prerogative, which the courts policed.
Parliament was recalled the next day - the rare constitutional ruling whose effect was immediate and visible. The chamber the executive had suspended was sitting again within twenty-four hours.
Not a devolution case - though the Cherry half of the litigation began in the Scottish courts, the ruling concerned Parliament's right to sit, not devolved powers.
Keep this row out of union essays; its work is done in sovereignty and judiciary answers.
An 11-0 ruling, delivered by Lady Hale, on the first case ever to test the personal royal prerogative of prorogation - the courts' deepest step into the political arena in the modern era.
The unanimity matters in essays: not one of eleven justices thought the prorogation lawful.
The ruling settled the prorogation question and inflamed the wider one: a visible Supreme Court quashing a Prime Minister's decision sharpened the courts-against-politics argument that the codification debate and judiciary essays still run on.
A constitutional watershed: the first ruling on the personal prerogative, unanimous at 11-0, with Parliament recalled the next day. The codification packs use it both ways - proof the uncodified constitution can check the executive, and proof it took an emergency common-law improvisation to do it.
Preserved a single UK market after exit through mutual-recognition rules that constrain devolved divergence, with new UK government spending powers in devolved areas - passed over the objection of all three devolved legislatures.
The sharpest post-Brexit assertion that Westminster keeps the last word over the territorial constitution.
Westminster legislated a single set of mutual-recognition rules for the whole UK market - the sovereign Parliament setting the post-Brexit trading framework for all four nations, whether their legislatures agreed or not.
Sovereignty asserted in exactly the Diceyan sense: no body above Parliament, and none beside it either.
The Act gave the UK government new spending and regulatory reach in devolved areas - powers to act directly in fields that had been devolved territory since 1998.
The executive-empowered column usually works through statutory instruments; here it worked through a statute that widened Whitehall's footprint outright.
The Commons passed the Act comfortably - the real argument was not between government and Parliament but between Westminster and the three devolved legislatures, all of which objected and were overridden.
Parliament's position did not improve; it was the instrument through which the centre asserted itself.
Passed over the objection of all three devolved legislatures - the clearest modern demonstration that the Sewel Convention, confirmed politically unenforceable in Miller 1, gives devolved consent no legal teeth. The Scottish and Welsh governments treated the mutual-recognition rules as overriding their competences.
This is the cell that links the Brexit grid to every devolution essay.
The fight stayed political rather than judicial: the devolved governments objected, protested and were overridden, but no court ruling defines the episode the way the Millers define theirs.
That absence is itself evidence - Sewel's unenforceability meant there was nothing to litigate.
Far from closing anything, the Act reopened the territorial argument Brexit had already strained: the devolved governments read it as a power grab, Westminster read it as sovereignty doing its job, and both readings persist.
The sharpest post-Brexit assertion of Westminster's last word: one statute constraining devolved divergence across all three settlements, passed over all three legislatures' objection.
In essays it is the bridge example - a Brexit statute whose main constitutional damage landed on the Union, proving the era's costs were territorial as much as legal.
The renegotiated Northern Ireland arrangement: smoother GB-NI trade lanes, EU law still applying to goods in Northern Ireland, and the Stormont brake giving the NI institutions a new lever over incoming EU rules.
The nearest the era has come to a settled UK-EU arrangement - and proof that full separation and full sovereignty do not coexist easily in Northern Ireland.
Under the Framework, Northern Ireland still follows many EU single-market rules on goods and the ECJ retains limited jurisdiction there - so for one part of the UK, pooled sovereignty has not fully ended. The arrangement exists to avoid a hard Irish border, which would have breached the Good Friday Agreement 1998.
Use it as the standing qualification on any claim that Brexit restored sovereignty completely.
The Framework was negotiated by Sunak's government at treaty level in February 2023 - the executive renegotiating the UK's external constitutional arrangements, with Parliament's role reduced to approval after the fact.
It is the treaty-making face of the executive-empowered column: deals first, votes second.
The renegotiated arrangement was presented to Parliament largely settled, with a single Commons vote held on the Stormont brake element rather than the package as a whole.
A treaty-level change to the UK's constitutional arrangements passed with less parliamentary process than an ordinary bill receives.
The Framework eased the strain the original Protocol had created: it simplified GB-NI checks with a green lane for goods staying in Northern Ireland, and the Stormont brake gave the NI institutions a new lever over incoming EU rules - relevant after the DUP had refused to participate in Stormont for two years.
The one row in this column where the territorial pressure went down, not up.
No court shaped the Framework - it was diplomacy, not litigation. The ECJ's limited jurisdiction in Northern Ireland continues under it, but as a negotiated term rather than a judicial outcome.
The nearest the era has come to a settled UK-EU arrangement - and it works by accepting that EU law keeps applying to goods in Northern Ireland. The later Starmer reset of May 2025 extended the same logic, returning ECJ jurisdiction over UK-EU fish trade.
The pattern for essays: post-Brexit stability keeps being bought with shared sovereignty.
Proof that full separation and full sovereignty do not coexist easily in Northern Ireland: the choice was a hard Irish border, an Irish Sea border, or continued EU rules in one part of the UK, and every government since 2019 has chosen the third.
In a sovereignty essay, Windsor is the disagree side's closing example - sovereignty is a choice, and the UK keeps choosing to share it.