It’s beginning to look a lot like a cover-up. Is that too cynical? Maybe we should just congratulate Boris Johnson on a wonderful piece of luck, a convenient turn of events just in the nick of time. Having seen nothing to investigate in the partygate affair until this week, the Metropolitan police swooped down at the very moment Sue Gray was ready to press print on her long-awaited report – one that threatened to terminate Johnson’s premiership – and stayed her hand. The Met told Gray she can say what she likes about parties in Downing Street, so long as she says nothing about parties in Downing Street. Or as it put it: “For the events the Met is investigating, we asked for minimal reference to be made in the Cabinet Office report.” It stresses that it “did not ask for any limitations on other events in the report”, which is a bit like saying: “On all the stuff that no one cares about, go ahead: knock yourself out.” Indeed, with this move, the Met have all but ensured that whatever remains of Gray’s report will, if ever published, be waved away by Johnson and his defenders: if Gray was allowed to publish it, they’ll say, it can’t be that serious. That is not where the bar should be set. The issue is not only whether Johnson was guilty of criminal violations of Covid regulations, but whether he broke a lockdown that he imposed on everyone else and whether he misled parliament. Those judgments cannot be outsourced to a police force, especially one led by a commissioner who has good reason to feel she only remains in her post thanks to the mercy of the prime minister. Those are decisions that should be made by politicians and voters, with access to all the facts. That prospect is receding. Gray now faces a choice: either publish a gutted version of her report, which Downing Street will falsely spin as having cleared the prime minister, or delay it until the police have completed their work. It’s all too plausible to imagine a Met statement, weeks or months from now, announcing that, having conducted its investigation, it has concluded that no further action need be taken. Team Johnson will spin that too as exoneration. And whatever facts Gray discovered will remain in the drafts folder of her laptop. What would be the effect of that? I don’t mean in narrow political terms, though it would clearly boost Johnson’s prospects of retaining his job. I mean the consequences for our public and collective life. What does it do to a country to be led by a documented liar? That’s a question we can ask with or without the Gray report. We can put aside the entire partygate affair and the question still stands. Even Johnson’s admirers concede his proven record of mendacity. They know that he was sacked twice for lying, once by the Times, once by Michael Howard, then his party leader. They remember the fictional £350m on the side of the bus. They have seen more evidence of his dishonesty this week, when documents emerged saying Johnson intervened personally to help Pen Farthing get his animals out of Kabul – ahead of desperate Afghans whose help for Britain had put a Taliban target on their backs – despite the prime minister’s insistence that he had done no such thing. The pattern is so clear, it cannot be denied. What is that doing to us? We can see the effect in two countries that are or were led by practised liars. Vladimir Putin is what the moral philosopher Quassim Cassam calls “a strategic liar”: his lies are part of a worked-out strategy, aimed less at convincing the Russian public than confusing it, making it dependent on the strongman in the Kremlin who can present himself as the only source of clarity in a fog of doubt. Donald Trump’s lies, meanwhile, fall into the “pathological” category, a function of a sociopathic personality. The effect in the US is obvious enough: Trump, in office and out of it, has entrenched a situation in which a large chunk of the American population inhabits a realm heedless of truth, evidence and science. The strongest predictor of whether or not an American has taken the Covid vaccine is whether or not they voted for Donald Trump. Johnson is his own case. The £350m was a strategic lie, advanced to great effect, but many of his lies are casual and opportunistic, the kind of lie someone offers to get themselves out of a tight spot, “the kind of lie”, says Cassam, “that people who have affairs have to tell”. It is a habit Johnson cannot break. He could, for example, have defended his role in the Kabul pet airlift. Instead he denied it. It was his first reflex. Even casual lies have their effect. The first could be a shift in democratic norms, which change more than you might think. It was once taboo for a chancellor to reveal any of his budget until he had delivered it: in 1947, Hugh Dalton had to resign for breaking that unwritten rule. Now it’s routine for chancellors to give the papers multiple sneak previews of their budgets. The old norm faded. We may well be witnessing another, much more significant shift right now, upending the convention that a minister proven to have misled parliament must resign. If Johnson stays, that norm will come to look as archaic as the one that felled Dalton. Will the Johnson effect spread beyond Westminster, so that even among regular people the taboo on lying erodes? It’s tempting to laugh that off, to insist that few Britons base their day-to-day behaviour on the conduct of politicians. Besides, the insistence on truth is one norm that society cannot afford to let slip. As Cassam notes: “Human beings are social beings, who need to be able to rely on each other. That requires trust, and trust requires truth-telling.” But there is a third zone, between parliament and day-to-day life: namely, our public institutions. It’s naive to think that they are not affected, or contaminated, by the actions of the man at the top. If Johnson’s lies go unpunished, that will surely alter the norms that currently govern, say, senior civil servants. Which prompts a much sharper worry. If the public decides it can no longer trust those in authority, then when the chief medical officer stands up to warn of a new threat to public health, there is no guarantee that anybody will listen. In the US, they’re halfway there. The death threats against Dr Anthony Fauci are so frequent and severe, he now has 24-hour armed security. As trust has declined, it’s been replaced by “raw anger and hatred, conspiracy theories to explain the world, the belief that facts and evidence do not matter”, says Peter Pomerantsev, a keen student of politicians’ lies and author of This Is Not Propaganda. That’s what can happen when a liar runs the country. In November 2020, Americans got rid of theirs. Ours clings on – and now, it seems, his friends in the Met have helped him live to fight another day. Jonathan Freedland is a Guardian columnist