Boris Johnson could face a by-election which could cause him to lose his seat in Parliament if the Privileges Committee probe finds he misled MPs with his Partygate scandal explanations.
The prime minister, who will leave 10 Downing Street before the probe into his conduct concludes, is being investigated by the Committee to see if he committed contempt of Parliament by lying to MPs with claims Covid rules were always followed in government.
Commons Speaker Sir Lindsay Hoyle confirmed that the committee’s findings would fall within the remit of the Recall of MPs Act, following advice from a leading lawyer.
The Act allows constituents to trigger a by-election if an MP is suspended from Parliament for ten days or more - or if they are sentenced to jail or convicted of breaking expenses laws.
Critics insist Mr Johnson misled Parliament and his denials of rule breaking were proven to be untrue when police fined him and dozens of government staff members for breaking coronavirus laws.
Mr Johnson has repeatedly denied knowingly misleading Parliament, insisted he was always honest in the Commons to the best of his knowledge and was never intentionally dishonest.
The committee, however, said "intention is not necessary for a contempt to be committed" and would only be considered when looking at necessary punishments.
The committee plans to hear evidence from Mr Johnson himself and from whistleblowers, whom it has been said can remain anonymous if they wish.
How could Boris Johnson be removed from Parliament?
If it is decided, “on the balance of probabilities” (a lower standard than the criminal test of “beyond reasonable doubt”), that the prime minister did commit contempt of Parliament, it has a range of sanctions available to it, which includes suspension from Parliament.
Under the Recall of MPs Act 2015, if an MP is suspended for ten sitting days, or 14 days in total, they will be subject to a recall petition, which can result in the calling of a by-election.
If an MP suspension passes the 10-day threshold, a petition will be set up in their constituency, asking locals if they want a by-election.
If 10% of eligible voters in that constituency agree, there will be a by-election. There is no rule preventing a suspended MP from standing again.
MPs in the Commons would have to vote upon the recommended suspension for it to be enforced and it's possible the sanction could be rejected, as it was with Owen Paterson, however that is unlikely.
There more harsh sanctions available to the Commons however they are extremely rare and unlikely to be used.
The power to imprison - or fine - for example, has not been used by Parliament in well over 100 years.
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When will the investigation conclude?
Those submitting documentary evidence will have until July 29 to do so and oral evidence sessions will take place in the autumn.
A conclusion is not likely until winter, according to the think tank Institute for Government.
The Privileges Committee has insisted its inquiry will go ahead despite Mr Johnson’s resignation as Tory leader and his expected departure from No 10 in September.
The committee said “some have suggested” the inquiry is no longer necessary.
“Our inquiry, however, is into the question of whether the House was misled, and political developments are of no relevance to that.
“The House charged the committee with this task and we are obliged to continue with it.”