The House of Commons privileges committee is besotted with Boris Johnson. No sooner did we breathe sighs of relief as he disappeared over the horizon three weeks ago, than the committee has hauled him back for another thrashing in the headlines. This time it is aiming at his “friends and allies”, who called it a kangaroo court and a witch-hunt. These friends stand accused for their vociferous and unprecedented remarks, offending, harassing, belittling and showering the committee with contempt. It has duly “named” them, though to what end is unclear. Everyone knew their names. We were fed up with Nadine Dorries, Jacob Rees-Mogg, Priti Patel and assorted peers, all honoured by Johnson, desperately defending him as the committee’s hearings into Partygate dragged on. They argued, in private and in public, that Partygate was not the most earth-shattering of offences for which Johnson might reasonably have been condemned. No one died. He grovelled, apologised profusely, and returned to business. He said he did not “intentionally” deceive MPs because, like Don Giovanni, he genuinely thought he was telling the truth at the time. Critics of the committee, who extend beyond Johnson’s friends, also point out that prime ministers distort, befuddle and deceive at the dispatch box week after week. Attacking them is the job of the opposition, which it also does week after week. Must all statements at the dispatch box now be subject to a Commons inquiry? If this committee’s job is to protect the good name and reputation of the house, why has it been so silent on corruption, conflicts of interest, dodgy aides and fiddled expenses? In sum, the case against the committee’s latest intervention is that is being absurdly oversensitive. It is surely a right of MPs to express a view on a matter that had long reduced the hothouse of national politics to a frenzy. Surely we can get over it and move on. In response, the committee argues that under Johnson, parliament was persistently bypassed and deceived. Its job is to guard against that. Its work is unique. Members of parliament enjoy the constitutional right to speak freely in the chamber, untrammelled by fear of legal action or other retribution. That in turn demands they firmly police themselves. The committee is that policeman. That is why respect for the committee’s authority is vital. The membership carries a governing party majority, while the chairwoman is drawn from the opposition. Parliament may neglect any obligation to reform itself. The weight of history, so long regarded as its glory, risks plunging it into political irrelevance. But it must guard its rights and dignities and be respected. Johnson’s friends did not respect it; they insulted it. The committee can also point out that in this case it was merely advising the Commons. It was for MPs collectively to pass judgment on Johnson, a decision he funked by resigning his seat. In the event, only seven friends voted against the committee. A reasonable conclusion is that the committee was right to take Johnson’s mendacity to the Commons seriously, but its response does appear disproportionate. The drawn-out investigation of Johnson’s role in Partygate, three years after the event, was dilatory and thus appeared partisan. So did the severity of the punishment, in effect seeking to strip Johnson of his seat and his job, by triggering a recall election. By now it has more than achieved its goal. It has driven Johnson out of parliament with the overwhelming support of MPs. It can surely ignore Johnson’s tinpot barmy army. Let them dribble away, and let this wretched episode finally end. Simon Jenkins is a Guardian columnist