Boris Johnson has already been tried in the court of public opinion over Partygate, having given up the keys to No 10 when Conservative MPs and cabinet ministers mobilised en masse against him.
But the chance to rebuild his powerbase as a backbencher and chart a course back to Downing Street could suffer a serious setback when an inquiry into whether he recklessly misled parliament concludes.
What sanction could he face?
The seven-strong privileges committee of MPs, chaired by Labour’s Harriet Harman but with a Tory majority, will write a report with their definitive judgment about whether or not Johnson misled parliament.
If they find against him, the group will decide if his action was intentional or reckless.
Crucially, they would then recommend a sanction for Johnson to face.
There are a range of potential penalties that can be recommended by the standards committee, which is made up of the same MPs but adjudicates on alleged breaches of Commons rules rather than parliamentary privileges.
These include a written apology, docking of salary or suspension from the Commons for a specific period.
What difference would the sanctions have?
Johnson has protested his innocence, so is likely to fight any penalty.
But the sanction with the most serious implications would be a suspension from the Commons for 10 days or more.
That would automatically trigger a recall petition, allowing voters in Johnson’s Uxbridge and South Ruislip constituency to trigger a byelection if 10% of them call for one.
Three recall petitions have been triggered in recent times.
Two were successful – both in March 2019: 19% of voters in Brecon and Radnorshire backed the move after an expenses scandal involving Tory MP Chris Davies, and 28% of voters in Labour MP Fiona Onasanya’s Peterborough seat did the same when she was jailed for perverting the course of justice.
What happens after the committee makes a recommendation?
Any sanction along with the report on an MP’s misconduct has to be approved by the Commons as a whole.
Traditionally, “House matters” are not whipped – meaning the government and opposition parties should not dictate to their MPs how to vote.
However, that precedent was shattered by Johnson when Tory whips instructed their MPs to vote to save Owen Paterson from suspension for breaking lobbying rules.
Rishi Sunak is said to be keen for it to be a free vote.
Johnson still has a loyal following among some in his party – having secured the backing of more than 100 MPs during the autumn Tory leadership race.
But many fear that anything that plunges the Conservatives back into a standards row and reopens the wounds of the Paterson debacle should be avoided at all costs.
If a suspension of more than 10 days is recommended by the privileges committee, the motion is amendable. This may lead to wrangling, as Johnson’s allies try to reduce the severity of the punishment.
What happens if a recall petition is triggered?
Johnson’s constituents will have six weeks to decide his fate.
A petition would be set up at at least one “signing station”, with voters able to put their name to it from Monday to Friday, 9am to 5pm (except bank holidays).
Anyone who is registered and eligible to vote in a parliamentary election in Johnson’s constituency would be able to sign the petition.
If 10% of them did so, a byelection would be called. Johnson would still be able to stand in it, and has recently been reselected as the Conservative candidate in the run-up to the next general election.