Does the Brexit crisis show Britain needs a written constitution?

Gordon Brown, the former prime minister, has accused Boris Johnson of “shredding the constitution” of the UK after he suspended parliament for five weeks. Experts say the political crisis over Brexit is not yet a constitutional crisis, but it could soon become one. Recent events have revived a debate over whether the UK needs to codify a largely unwritten constitution, which makes it unusual among democratic countries even though it invented parliamentary democracy.

Only New Zealand and Israel have an “unwritten constitution”. Parts of the UK’s arrangements are written down – the Fixed-term Parliaments Act 2011; the legislation setting up devolved administrations in Scotland, Wales and Northern Ireland; the cabinet manual and the ministerial and civil service codes. The system relies on politicians to respect conventions and legal precedent. But supporters of reform argue that the current crisis has highlighted the need for a constitutional commission.

At its heart would be the relationship between referendums and representative democracy: does the 2016 referendum result justify a no-deal Brexit, or should parliament decide the terms? A review would also look at the relationship between parliament and the government, which is about to be strained when MPs return from their summer break on Tuesday. It would include ministers’ use of the royal prerogative – powers exercised on behalf of the monarch without parliament’s authority. They allowed Mr Johnson to advise the Queen to prorogue parliament and gave her no option but to take his advice. A vexed question is whether military action should be approved in advance by parliament. A highly topical one is whether a prime minister should resign after losing a no-confidence vote.

The Commons Political and Constitutional Reform Committee mapped out three routes to “a new Magna Carta” as its 800th anniversary approached in 2015. They were: a constitutional code sanctioned by parliament, without statutory authority; a constitutional consolidation act; and a written constitution, a single document of basic law setting out the relationship between state and citizens.

Defenders of the present system insist it is flexible and has enough checks and balances to prevent “an elective dictatorship”. They warn that a written constitution would politicise judges and result in a stream of court cases (although three separate cases over Brexit are now under way). They say the existing regime has ensured stability, though that will be tested over the next two months.

A written constitution could be considered during a citizens’ convention on UK democracy to be launched in January. But commissions have come and gone, and little has changed even though the system itself has markedly – through devolution; freedom of information; the Supreme Court; the Human Rights Act; the abolition of most hereditary peers and the Fixed-term Parliaments Act.

Arguably, a new constitutional blueprint might never be a big enough political priority, with any government likely to be more interested in the economy, public services and, of course, its own re-election. One for a future Lib-Lab coalition? Perhaps – under new management. Even if there is piecemeal rather than a “big bang” reform, lessons must surely be learnt from the current crisis.