MP Margaret Ferrier has lost an appeal to have her suspension from the Commons overturned for breaking covid rules.
The decision means a crunch by-election in Rutherglen and Hamilton West has moved a step closer.
Ms Ferrier, who sits as an independent after losing the SNP whip, received a community payback order after she admitted travelling by train from London to Scotland following a positive Covid test in 2020.
A Westminster standards watchdog then recommended a 30 day suspension – a sanction she appealed.
The panel concluded: “The Committee’s recommended sanction is upheld.”
Dismissing Ms Ferrier’s appeal against the proposed 30-day suspension, the Independent Expert Panel said: “She acted with blatant and deliberate dishonest intent.
“She acted with a high degree of recklessness to the public and to colleagues and staff at the House of Commons.
“She acted selfishly, putting her own interests above the public interest. There could therefore be no lesser sanction for this conduct.”
The report stressed that MPs are “expected to be held to a high standard of conduct as well as honesty”.
It added: “When members fall short of that conduct, the trust and confidence in Parliament and its members are undermined.”
Ms Ferrier had argued that the proposed 30-day ban “amounts to double jeopardy, since she has already been penalised by the Sheriff Court”.
But the report from the Independent Expert Panel said: “We do not agree. There is no double jeopardy here.”
It insisted the criminal proceedings against Ms Ferrier and the “workplace disciplinary proceedings” she now faces “are quite different”.
The report went on to describe her as being “dishonest”, pointing out she had not told anyone at the Commons she had tested for Covid, and when his came back positive, she failed to inform the Parliamentary test and trace team and did not tell the SNP chief whip.
The panel stated: “Ms Ferrier’s failure was not a single misjudgement, but a series of deliberate actions over several days.”
The report said the MP’s actions “demonstrated, in particular, a lack of honesty” – adding that this was one of “seven principles of public life”.
At a time when others “both across the country and within the Parliamentary community, made significant sacrifices in order to follow the rules and guidance during the Covid-19 pandemic”, the report said Ms Ferrier “knowingly exposed others to risk”.
Ms Ferrier has not indicated any intention to stand down, but Westminster insiders believe a by-election is highly likely.
If the suspension is agreed by a vote in the Commons, it would automatically trigger a recall petition, which if successful would see her sacked as an MP and an election in the seat called.
Scottish Labour, who selected teacher Michael Shanks to fight any by-election, believes they can take a seat they last won in 2017.
Ms Ferrier won the seat in 2019 with a 5,230 majority.
Last week it emerged the SNP had not selected a by-election candidate for the constituency.
The Times reported that First Minister and SNP leader Humza Yousaf rejected a slate of local candidates and entered into talks with alternative would-be MPs.
A contender to succeed Ms Ferrier was due to have been chosen by Friday, May 12, but the SNP paused the selection process.
Commenting on Ms Ferrier losing her appeal Scottish Labour deputy leader Jackie Baillie said: “With this news, the by-election that the people of Rutherglen and Hamilton West need has moved one step closer.
“It is simply disgraceful that this community has been left without proper representation due to the actions of Margaret Ferrier.
“Only by electing Michael Shanks as Scottish Labour MP for Rutherglen and Hamilton West can the people of the area get the representation and the clean start that they deserve.
“At the coming by-election, only Scottish Labour is standing for change. Join us on that journey.”
Scottish Liberal Democrat deputy leader Wendy Chamberlain MP said: “At a time when so many Scots were staying home to keep themselves and others safe, Margaret Ferrier acted with real recklessness.
“Today’s news takes us one step closer to a recall petition and a long overdue by-election.
“Rutherglen and Hamilton West deserve fresh representation and a chance to show the nationalists that they are fed up of being neglected.”
An SNP spokesperson said: “There must now be a by-election in Rutherglen and Hamilton West, which the SNP has been calling for since Ms Ferrier’s Covid rule breach first came to light in 2020.
“The SNP is ready to take the fight to the Tories and pro-Brexit Labour Party at that by-election – and we will be putting the cost of living, NHS and independence at the heart of our campaign.
“We will be working hard for every vote to ensure the people of Rutherglen and Hamilton West can have a strong SNP MP to stand up for their interests locally and for Scotland.”