The British Constitution’s Unwritten Rules: The Conventions That Hold Everything Together and Break at the Worst Moments

Collective Responsibility, the Sewel Convention, Salisbury Convention, Caretaker Conventions, the Lascelles Principles, and the Gentleman’s Agreements That Govern a Nation

The Rules Nobody Wrote Down: Britain’s Most Important Laws That Are Not Laws

Constitutional conventions are the most distinctively British feature of a system that already has more distinctively British features than most constitutional systems can comfortably contain. They are rules — binding in the sense that political actors treat them as binding, not in the sense that courts will enforce them — that govern the most important aspects of British political life: how governments are formed, when they must resign, how ministers behave collectively, how the Lords treats the Commons’ programme, and how the devolved governments relate to Westminster. They exist because the British constitution accumulated over centuries through practice rather than design, and because nobody at any of the critical moments — 1688, 1832, 1911, 1997 — sat down and wrote out the rules explicitly, preferring instead to rely on the shared understanding of political actors who knew what was expected.

The shared understanding works beautifully when the political actors have been socialised into it, share its assumptions, and have sufficient respect for the institution they inhabit to constrain their behaviour in deference to it. It works less well when political actors actively test conventions to determine how far they can be pushed, when the conventions produce outcomes that one party finds intolerable, or when the convention’s content is disputed between people who are ostensibly bound by it. The last decade has provided several illustrations of all three conditions, which is why constitutional conventions have become a matter of public interest rather than the specialist concern they appeared to be in the years when everyone was broadly following them.

Collective Ministerial Responsibility: The Convention and Its Creative Interpretation

Collective ministerial responsibility — the requirement that all Cabinet ministers publicly support government decisions regardless of their private views, and resign if they cannot — is the convention whose breach is most visible and whose enforcement is most variable. The convention has several obvious purposes: it ensures that government presents a united front to Parliament, prevents ministers from publicly undermining each other, and requires that disagreement is resolved within Cabinet before being expressed publicly. It also, less advertised, requires ministers to publicly endorse decisions they believe to be wrong, which is either a reasonable price for collective governance or a significant constraint on political honesty depending on the decision in question.

The convention’s creative periods include: the 1975 EEC referendum, in which Harold Wilson suspended collective responsibility to allow ministers to campaign on either side; the 2016 Brexit referendum, in which David Cameron made the same suspension; and the Boris Johnson years, in which collective responsibility was maintained with sufficient flexibility to accommodate ministers who had publicly disagreed with government policy, been reshuffled rather than required to resign, and occasionally denied saying things that they had said on camera. The convention bends in practice without breaking in theory, which is exactly the kind of constitutional arrangement that produces both resilience and frustration in equal measure.

The Sewel Convention: Westminster’s Undertaking to Holyrood That Brexit Strained

The Sewel Convention — named after Lord Sewel, who introduced the relevant amendment during the Scotland Bill’s passage in 1998 — holds that Westminster will not normally legislate on devolved matters without the consent of the relevant devolved legislature. “Normally” is the word that does the constitutional work: it acknowledges that Westminster retains sovereign authority to legislate on anything, while committing to seek consent as the normal practice. The convention was given statutory expression by the Scotland Act 2016, which stated that Parliament would not normally legislate on devolved matters without consent. Statutory expression of “normally” is an interesting constitutional move: it makes the convention visible while preserving the flexibility that “normally” contains.

Brexit tested the Sewel Convention systematically: the European Union (Withdrawal) Act, the UK Internal Market Act, and several other Brexit-related pieces of legislation affected devolved competences without the consent of devolved legislatures, which consistently withheld it. Westminster legislated anyway. The convention was observed in the breach with a consistency that the devolved governments found constitutionally alarming and Westminster found practically necessary. The Scottish Government’s position — that the convention had been fundamentally undermined — and Westminster’s position — that the convention’s “normally” qualification applied — represent a genuine constitutional disagreement about what the convention means, which is the kind of disagreement that codified constitutions avoid and uncodified ones accumulate.

The Salisbury Convention: The Lords’ Undertaking to the Elected Government

The Salisbury Convention — that the House of Lords does not block legislation that was in the governing party’s election manifesto — was formulated after the 1945 Labour landslide when the Conservative-dominated Lords needed a principle to guide its relationship with a Labour government it had not expected and could not ignore. The convention has been broadly observed since, with the significant complexity that “in the manifesto” is not always a clear category: manifesto commitments vary in specificity from detailed policy to broad direction, and the Lords have found, on occasion, that what they are blocking is not quite the manifesto commitment but something adjacent to it or beyond it.

The convention’s most interesting recent application concerns manifesto commitments made by governments elected on minority or plurality vote shares — Labour’s 2024 majority on 34% produced the question of whether the Salisbury Convention applies with full force to a government whose manifesto the majority of voters explicitly did not endorse, which is either a democratic observation or a constitutional innovation depending on your view of what the convention was designed for.

The Caretaker Convention: What Government Can Do When It Has Lost and Not Yet Gone

The caretaker convention — governing what a government that has lost an election or lost a confidence vote can do before its successor takes office — is one of the least discussed and most practically significant conventions. During a dissolution period and the days between election results and new government formation, the incumbent government remains in office but convention restricts it to routine, day-to-day administration, prohibiting major policy decisions, significant appointments, or international commitments that would bind the incoming government without its consent.

The convention was tested in 2010 when Gordon Brown remained in Downing Street for five days after the election while coalition negotiations proceeded — a period in which the Cabinet Secretary Sir Gus O’Donnell managed the transition with a manual published before the election specifically for the purpose, because the prospect of a hung parliament had made the absence of a published convention uncomfortably visible. The Cabinet Manual, published in 2011, documented conventions that had previously been unwritten, converting them into something between a convention and a codification — a publication that is not legally binding but is sufficiently authoritative that departing from it requires explanation.

Auf Wiedersehen, amigo!

Constitutional conventions are politically binding rules governing British governance that are not enforceable by courts. Collective ministerial responsibility requires ministers to publicly support Cabinet decisions; exceptions have been granted for referendums (1975, 2016). The Sewel Convention commits Westminster to seeking devolved consent before legislating on devolved matters; it was breached systematically during Brexit legislation. The Salisbury Convention commits the Lords not to block manifesto legislation. The Cabinet Manual (2011) documents conventions previously unwritten. The caretaker convention restricts incumbent governments after election defeat or confidence vote loss to routine administration. The Lascelles Principles (1950) govern when the monarch may decline to dissolve Parliament — in practice, relevant only in constitutional emergency conditions.

Alan Nafzger

Alan Nafzger was born in Lubbock, Texas, the son Swiss immigrants. He grew up on a dairy in Windthorst, north central Texas. He earned degrees from Midwestern State University (B.A. 1985) and Texas State University (M.A. 1987). University College Dublin (Ph.D. 1991). Dr. Nafzger has entertained and educated young people in Texas colleges for 37 years. Nafzger is best known for his dark novels and experimental screenwriting. His best know scripts to date are Lenin’s Body, produced in Russia by A-Media and Sea and Sky produced in The Philippines in the Tagalog language. In 1986, Nafzger wrote the iconic feminist western novel, Gina of Quitaque. He currently lives in Holloway, North London. Contact: [email protected]