"Daily Mail editor Paul Dacre last night launched a passionate defence of press freedom." So reported the Daily Mail yesterday. He made a speech attacking what he claimed was a privacy law being introduced by the back door, aiming his steel-toed boots at one particular judge.

Dacre, the nation's bully-in-chief is, like all bullies, a coward: he refused to go on the Today programme yesterday to argue his case. He never dares face his critics, happy to fry alive all and sundry, never apologising, never explaining. There is a good reason for this: the stance his paper takes on just about everything is so internally contradictory and inconsistent that he could never survive even minimal scrutiny. The Mail's mishmash of lurid scandal, bitching about women and random moralising zigzags all over the place, dishing out pain and praise often according to who it has succeeded in buying with its limitless chequebook, or who has infuriated it by selling their wares to another bidder.

Dacre was protesting at Mr Justice Eady's verdict, which found the News of the World had no right to expose the private life of formula one boss Max Mosley. Delicate Guardian readers may find it hard deciding whether Max Mosley or Paul Dacre is the more unsavoury character. But there's no doubt which of them does most harm: Dacre - along with Rupert Murdoch in his different way - probably does more damage to the nation's happiness and wellbeing than any other single person, stirring up hatred, anger, fear, paranoia and cynicism with his daily images of a nation going to hell in a downward spiral of crime and depravity.

Dacre attacked the judge on these grounds: that he "effectively ruled that it was perfectly acceptable for the multimillionaire head of a multibillion sport, followed by countless young people, to pay five women £2,500 to take part in acts of unimaginable sexual depravity with him ... Most people would consider such activities to be perverted, depraved, the very abrogation of civilised behaviour ... Would he [the judge] feel the same, I wonder, if one of those women had been his wife or daughter?" This last thought is an archetypal example of Dacre's creepy mind and corkscrew logic.

Whatever else Max Mosley may or may not be, he's no coward. To bring a case against the News of the World for breaching his rights under what Dacre calls "the wretched human rights act", was brave. It guaranteed excruciating public examination of exactly what he got up to in his German-themed spanking session. But he fought for the good principle that what people do in private is nobody else's business, unless it's illegal - or, in rare cases, unless it exposes some gross hypocrisy in a public figure. Since Mosley does not go about inveighing against prostitution or sadomasochism - and all this has nothing to do with motor racing - it doesn't apply to him. This was a landmark case that may make the media think twice before exposing irrelevant, if fascinating, facts about people's private proclivities.

Press freedom is precious - but it doesn't depend on the right to be prurient. The right to privacy is precious too: one article can destroy a reputation, and that can never be reclaimed with any puny compensation or apology. There is no "press freedom" to tell us exactly what everyone does without their clothes on. Torturers use sexual humiliation because it violates deep instincts: newspapers that expose people administer their own torture. Who wouldn't prefer Mr Justice Eady protecting people's reasonable right to privacy than Judge Paul Dacre waving his chequebook from his tawdry pulpit, deciding who shall be whipped in public for which sins.

A good example of Dacre's "morality" was last year's treatment of Faye Turney, the leading seaman captured by the Iranians, who along with the others was permitted by the Ministry of Defence to sell her story. The Mail was outraged and over pictures of coffins of dead soldiers, filled the front page with the headline, "They won't be selling their story, minister". But one key element was missing from the paper's reporting. The Daily Mail and the Mail on Sunday made their own bids for Turney's story, "with a very substantial sum", according to the MoD, as they wooed her with money, flowers and sympathy. When she sold her story elsewhere, they savaged her as an unfit mother, among other things. So when Dacre in his speech this week boasted of his paper's "duty to take a moral stand", while accusing Eady of having "a subjective and highly relativist moral sense", he knows whereof he speaks.

Dacre rounded off his speech with another hit at the BBC. His campaign is reaching the edge of hysteria: the Mail on Sunday's front-page splash, "BBC bungles Sachs apology" was about failing to apologise to other members of the Sachs family. How barking is that? The feeding frenzy against the BBC, spurred on by Dacre and Murdoch, grows ever more threatening. It matters because politicians are afraid of both men. More sinister than the trip to Deripaska's yacht was the less publicised visit by David Cameron to Murdoch's yacht on that same holiday. Obligingly, Cameron wrote a piece in the Sun last week joining in the anti-BBC hue and cry.

One reason why it's easy to despair of Gordon Brown is his incomprehensible and grovelling friendship with Dacre, Labour's worst enemy. Where was Brown on the eve of his party's disastrous Glasgow East byelection? He was far away at Stratford-upon-Avon, watching Hamlet with his good friend Dacre. The Mail plays a curious cat and mouse game with Brown, sometimes praising his moral qualities on inside pages while assaulting Labour on its front page. Dacre is said to be very close to the Browns - which makes you wonder about the spinning of the PM's much-vaunted moral compass.

Meanwhile, the scourge of measles is still rising; it is almost directly attributable to the Mail's weird campaign against the MMR vaccine - only now finally silent, with no apology. An inevitable consequence is a fall in vaccination rates. Couple that with Dacre's equally bizarre campaign against life-saving speed cameras on behalf of speeding motorists.

These are things a free press will always do. Sometimes it campaigns for good causes, sometimes for bad ones. However, the right to strip naked anyone the press chooses is surely one of the most morally dubious abuses of press freedom yet devised.

polly.toynbee@theguardian.com