Video report by ITV News Political Correspondent Romilly Weeks
Boris Johnson has denied he lied to the Queen when he advised her to prorogue Parliament, insisting such claims are "absolutely not" true.
Scotland's highest civil court said prorogation was "motivated by the improper purpose of stymying Parliament" and therefore advice to the Queen to suspend it was "unlawful".
But the prime minister disagreed, saying suspension was called because "we need a Queen's Speech, we need to get on and do all sorts of things at a national level."
His comments come after The Court of Session in Edinburgh effectively ruled he advised Queen to act unlawfully when he asked for Parliament to be suspended.
Video report by ITV News Europe Editor James Mates
The court ruled therefore that prorogation is itself is "unlawful", "improper" and as a result, "null and of no effect."
Mr Johnson said in response to the ruling: "The High Court in England plainly agrees with us but the Supreme Court will have to decide."
Asked whether he lied to the Queen, he said: "Absolutely not".
The government will now appeal and a formal order will not come before Tuesday, when the Supreme Court hears the case.
A similar case heard in London's High court was dismissed.
Mr Johnson said he would not "quarrel or criticise" the judges in the case as he insisted they are independent, after media reports quoted a Downing Street source suggesting judges were not impartial.
He said: "The British judiciary, the United Kingdom judiciary, is one of the great glories of our constitution - they are independent."
He added: "Clearly there are two different legal views - the High Court in England had a very different opinion and the Supreme Court will have to adjudicate in the course of the next few days, and I think it's proper for politicians to let them get on and do that."
A summary of the court opinion, published by the Scottish Courts and Tribunals Service, said Mr Johnson's decision to prorogue Parliament was "motivated by the improper purpose of stymying Parliament".
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."
Mr Johnson also sought to downplay the impact of a no-deal Brexit following the release of Operation Yellowhammer assessments.
He insisted the document - the government's Brexit contingency plan - is a "worst-case scenario which civil servants obviously have to prepare for".
He says government work to mitigate the impacts have been accelerated "massively" since he moved into Number 10.
He went on: "We're trying to get a deal and I'm very hopeful that we will get a deal with our European friends on October 17th or 18th or thereabouts.
"But if we have to come out on October 31st with no-deal we will be ready and the ports will be ready and the farming communities will be ready, and all the industries that matter will be ready for a no-deal Brexit.
"What you're looking at here is just the sensible preparations - the worst-case scenario - that you'd expect any government to do.
"In reality we will certainly be ready for a no-deal Brexit if we have to do it and I stress again that's not where we intend to end up."