A legal bid to challenge the suspension of Parliament has succeeded at the appeal court in Edinburgh.

A group of around 70 parliamentarians had appealed against a ruling by a judge that Boris Johnson’s prorogation of Parliament was lawful.

Judge Lord Doherty dismissed a challenge against the suspension at the Court of Session last Wednesday, saying it was for politicians and not the courts to decide.

But three judges of the Inner House, the supreme civil court in Scotland, disagreed with Lord Doherty’s ruling.

The UK Government plans to appeal against the latest ruling to the Supreme Court.

The ruling comes a day after the prorogation took place in the early hours of Tuesday, with Parliament now suspended for five weeks.

At the appeal hearing on Friday Aidan O’Neill QC, representing the parliamentarians, claimed prorogation was unlawful in his closing arguments.

He said: “A decision to prorogue shuts down Parliament. It is in those circumstances an attack on democracy.

“It is an attack on the balance of the constitution and therefore is unlawful.”

David Johnston QC, representing the UK Government, had argued it was not for the courts to get involved in what was a political decision.

The campaigners included SNP MP Joanna Cherry QC, Liberal Democrat leader Jo Swinson, Labour MP Ian Murray and anti-Brexit barrister Jo Maugham, of the Good Law Project.

A summary of the court opinion, published by the Scottish Courts and Tribunals Service, states: “The Inner House of the Court of Session has ruled that the Prime Minister’s advice to HM the Queen that the United Kingdom Parliament should be prorogued from a day between 9 and 12 September until 14 October was unlawful because it had the purpose of stymying Parliament.”

It continues: “All three First Division judges have decided that the PM’s advice to the HM the Queen is justiciable, that it was motivated by the improper purpose of stymying Parliament and that it, and what has followed from it, is unlawful.”

It went on: “The Court will accordingly make an Order declaring that the Prime Minister’s advice to HM the Queen and the prorogation which followed thereon was unlawful and is thus null and of no effect.”