If a no-deal Brexit happens on 31 October, could a government that took office soon afterwards reverse it?

Boris Johnson believes he will be the prime minister that delivers Brexit, with or without the backing of the Commons. While he may yet succeed, his triumph could be overturned within hours of the 31 October deadline. Andrew Grice explains

Should Johnson be forced out of No 10 after 31 October, could parliament pass retrospective legislation to delay or even cancel Brexit? (Getty)

Boris Johnson and his top adviser Dominic Cummings think they have a cunning plan to prevent a Commons vote of no confidence scuppering Brexit. If MPs opposed to a no-deal exit force a general election, Johnson would call it for a few days after 31 October, so it is too late to stop Brexit.

It’s a clever move, but perhaps not as clever as they think. Vernon Bogdanor, a professor in government at King’s College, London, believes he has found a flaw. He argues that, if Johnson failed to win an overall majority, an incoming government could reverse the UK’s departure even though it had happened. He told Politico: “I don’t believe an election in November could frustrate a Remain or anti-no-deal position. It is true the default position in Britain and the EU is that we leave on 31 October. But the British parliament is sovereign so it can pass retrospective legislation, and it did for example with the War Crimes Act of 1991 – parliament could deem we hadn’t left and seek an extension.”

Constitutional experts are like economists: put 10 in a room, and you get 11 opinions. Bogdanor concedes that not all his fellow experts agree with him. Mark Elliott, professor of public law at Cambridge University, believes the only legally watertight way to prevent no deal is legislation requiring the PM to revoke Brexit, which MPs have baulked at. He said: “Withdrawal occurs by default operation of EU law on Halloween. Domestic legislation cannot alter that, and the EU treaties provide no legal basis for retrospectively restoring UK membership.”