What is the Commons privileges committee and how powerful is it?

Boris Johnson has spent more than a year being investigated over Partygate. On Thursday, the findings of an inquiry into whether he misled MPs by repeatedly denying Covid laws were broken in Downing Street will be published.

What is the privileges committee?

The special body known as the committee of privileges looks into allegations that an MP has committed contempt of parliament.

Misleading the Commons, as opposition parties and some Tory MPs alleged Johnson has done, comes under this category.

While the committee has conducted numerous investigations before, the sitting prime minister has never previously been referred to it for scrutiny.

Who sits on it?

A cross-party group of seven MPs make up the committee. They are usually the same members as sit on the standards committee, given the two used to be combined until 2010.

Unlike the standards committee, the privileges committee does not have any extra lay members – independent people who are not politicians – appointed to sit on it.

There is an in-built government majority, with the four Conservative MPs consisting of Alberto Costa, Bernard Jenkin, Andy Carter and Charles Walker. Labour’s Harriet Harman is the chair, and another spot is held by Yvonne Fovargue, while the Scottish National party has one member, Allan Dorans.

It is one of only two committees that House of Commons rules dictate must have a Labour chair. It was led by Chris Bryant, but he had been a vocal critic of Johnson over Partygate so recused himself from the investigation and was replaced by Harman.

How did its investigation progress?

All MPs passed a motion last April instructing the committee to investigate whether Johnson misled parliament.

MPs on the committee demanded bundles of evidence, including WhatsApps, door logs and diaries kept by Johnson and his aides during the pandemic.

It did not set out to reinvestigate rule-breaking (given the police had already done so), but whether Johnson told the truth when he denied any Covid rules were broken and claimed he was repeatedly assured events in No 10 were within the rules.

The inquiry was slow to start; the government redacted large swathes of evidence, Harman took over from Bryant, and a Tory member was also replaced when they stepped down. The death of the Queen also delayed proceedings.

As the months went on, the committee tried to continue its work through a turbulent political environment – the downfall of Johnson’s government, followed by Liz Truss and then the rocky start faced by Rishi Sunak.

The government eventually relented and handed over unredacted evidence. Questionnaires were sent by the committee to witnesses, and a date was set for Johnson to give evidence in March 2022.

After his televised testimony session, the process was held up again by a new cache of files being handed to the committee by civil servants who were combing Johnson’s diaries in preparation for handing them over to the public inquiry into Covid.

The committee sent off its findings to Johnson in private last Thursday, giving him two weeks to respond. But Johnson claimed it had unfairly found against him and resigned as an MP to avoid facing any sanction.

The timetable for the report’s release was brought forward. But it faced one final delay this week.

The report was meant to be signed off by the committee on Monday, but Johnson sent a final submission that evening at 11:57pm. The report was finally formally completed on Tuesday, and is set to be published on Thursday.

What will happen next?

After the report is published, it will be up to the government to table a motion endorsing its findings. MPs can vote for or against it, abstain, and even table amendments, if they wish.

Government insiders have been drawing up plans for a motion that says the Commons has “noted” the report, rather than the traditional form of words for a committee report, which says MPs have “accepted” it.

Such a move is viewed as a way of encouraging Johnson’s supporters not to vote against the motion and spark further internal party ructions. The Commons leader, Penny Mordaunt, is expected to announce the date of the vote on Thursday morning. Sources said the vote was likely to be on Monday.