The government acted in “good faith” when it suspended Parliament, according to its chief legal adviser.
Attorney General Geoffrey Cox told MPs he was “disappointed” at the landmark ruling by the Supreme Court that the suspension was unlawful, but respected the judgement.
He then launched a blistering attack on MPs for being “too cowardly” to hold an election, calling them a “disgrace”.
MPs returned to work on Wednesday morning as a result of the ruling.
The SNP’s Joanna Cherry urged Mr Cox to publish the legal advice he gave the government ahead of the suspension.
Ms Cherry – who was one of the lawyers who led the court challenge against the suspension or “prorogation” – said Mr Cox was being “offered up as a fall guy for the government’s plans”.
The attorney general said the government believed its approach had been “both lawful and constitutional”, but he would “consider over the coming days whether the public interest may require a greater disclosure” of his advice.
Boris Johnson, who has flown back from a UN summit in New York to address MPs, has said he “profoundly disagrees” with the decision of the Supreme Court, but he would respect it.
He is due to give a statement to the Commons later, along with one from the Leader of the House, Jacob Rees-Mogg.
Opposition parties, meanwhile, are demanding that the prime minister resign.
Labour leader Jeremy Corbyn said the court’s decision had left Mr Johnson “badly wanting”, while the SNP said the country now had “a zombie prime minister and a zombie government” and both must be removed “in a timely manner”.
The prime minister could be ousted via a vote of no confidence – potentially triggering a general election – but Mr Corbyn said he would not seek one until it was “very clear” Mr Johnson would seek an extension to Brexit to prevent no deal and the EU had agreed to it.
Mr Johnson has said Brexit will happen with or without a deal on 31 October.
But MPs passed a law – the so-called Benn bill – to force him to ask for an extension from the EU if a deal – or approval for no deal – was not voted for by the Commons by 19 October.
The Supreme Court ruled it was impossible to conclude there had been any reason – “let alone a good reason” – to advise the Queen to prorogue Parliament for five weeks in the run-up to the Brexit deadline of 31 October.
Supreme Court president Lady Hale emphasised, though, that the case was “not about when and on what terms” the UK left the EU.
The PM insisted the suspension of Parliament had been necessary in order for him to bring forward a Queen’s Speech on 14 October outlining his government’s policies.
But the court found that the effect of such a move was to stop MPs scrutinising the government.
Back in the Commons on Wednesday after the ruling, MPs called for Mr Cox to distance himself from criticism of the judges.
Labour’s Hilary Benn asked whether he agreed with reported comments by Mr Rees-Mogg, who is said to have referred to the court’s actions as a “constitutional coup”.
The attorney general said things were sometimes said “in the heat of the rhetorical and poetic licence”, but added: “We are proud we have a country capable of giving independent judgements of this kind.
“With the judgements we can be robustly critical, with the motives we cannot.”
But exchanges in the Commons became more heated when Mr Cox hit out at MPs on the opposition benches for criticising the government, but not being willing to hold an election.
“This Parliament is a dead Parliament,” he said. “It should no longer sit. It has no moral right to sit on these green benches.
“This is a disgrace. They could vote no confidence [in the government] at any time but they are too cowardly.”
He also said an election motion would be “coming before the House shortly” – although offered no further detail.
When Boris Johnson addresses MPs this afternoon it’s going to be some moment. He’s not going to go in chastened, contrite – we’ll see him defiant and determined to press on with his 31 October Brexit deadline.
Indeed, this morning’s combative performance from Geoffrey Cox was a hint of what’s to come – attacking the opposition for being “too cowardly” to back an election.
And it’s true they do want to wait – they believe Mr Johnson is on the ropes, but don’t want to deliver the killer punch just yet.
The real problem for the PM is this. For all the headlines he may get, all the personal satisfaction he may derive, from presenting this as the people vs the elite – an out-of-touch Parliament and judiciary – nothing changes the hard truth.
Mr Johnson is a prime minister deadlocked in Westminster and deadlocked in Brussels.
Former Tory leadership contender Rory Stewart – who had the party whip removed after backing plans to prevent a no-deal Brexit – expressed shock at the remarks.
He tweeted: “I am horrified that when I asked the attorney general to confirm the principle of the sovereignty of Parliament that he appears to have replied – over the shouts of the House – that ‘this Parliament is a disgrace.’
“Our democracy can only be and must remain founded in Parliament.”
A furious Barry Sheerman also said the attorney general had “no shame”.
The Labour MP added: “To come here with his barrister’s bluster to obfuscate the truth? For a man like him, a party like this and a leader like this… to talk about morals and morality is a disgrace.”
And former Tory minister Amber Rudd – who resigned over the government’s handling of Brexit – urged Mr Cox to “cease this language of pitting Parliament against the people”.
“This Parliament was elected in 2017,” she said. “It reflects the divisions in our country, the divisions in our community and the divisions in our families. The failure is we have not yet reached a compromise.”
Mr Cox replied: “If I had not been driven to this language, I would never have used it.”
MPs twice refused to back the prime minister’s call for an election earlier this month – he needs the support of two-thirds of the House to hold one under the Fixed Terms Parliament Act.
Opposition parties say they want to wait until after the PM has asked for a Brexit extension as required by the Benn bill.
He has repeatedly insisted he will not do that.
Mr Cox said there was “no question of this government not obeying the law” within the Benn bill, although “there is a question as to precisely what obligations the law might require of the government”.