Perhaps the most revealing Roy Cohn anecdote in this extraordinary book concerns the time, in 1955, when the infamous lawyer took Barbara Walters out on a first date. Cohn picked up the TV star in his car and drove her to the 21 Club in midtown Manhattan. The traffic was awful and they got stuck. Nothing unusual there, except Cohn became furiously impatient, dragged Walters out onto the street, abandoned the car and walked the rest of the way to the club. Walters was astonished. ‘He had to be the most arrogant, inconsiderate man I’d ever met,’ she later recalled. She went on to become one of his best friends.

This stunt is a mere footnote in Cohn’s life, but it tells us much about the man: a reckless gambler who behaved as though the rules didn’t apply; a homosexual who was never entirely comfortable with his own sexuality; and a primal force whose charisma drew people to him despite his savagery.

Ever since Donald Trump won the presidential election in 2016, there has been a boom in Roy Cohn studies. It was Cohn, so the story goes, who took a brash Queens property heir and turned him into the King Kong of Manhattan, teaching him the rules of the jungle: play the man not the ball; always sue, never apologise; lie and lie and lie again. Cohn is seen as the key to understanding Trump, and so in recent years we’ve had the 2019 documentary Where’s My Roy Cohn? and the 2024 movie The Apprentice, with Jeremy Strong as the slippery protagonist. Now comes this weighty biography from Kai Bird with the help of his wife, Susan Goldmark (who did much of the research).

Contextualising Trump through Cohn is an interesting exercise. The two men had a close, avuncular relationship. When Trump bought the Commodore Hotel in 1976 – his first big Manhattan deal – it was Cohn who engineered an astonishingly favourable tax abatement, saving his client approximately $4 million a year. But Cohn’s life is fascinating on its own terms and, in fairness to Bird, this venereal-warts-and-all biography has the lot: Mafia goombahs, bent judges, waterskiing catamites. At times you can almost smell the semen-soaked, cocaine-encrusted bathrooms of Studio 54. During one Cohn orgy, we are told, someone had sex with a dog. On another unusual car journey, Bird informs us pruriently, Cohn sat facing backwards so that the fan could cool his infected posterior.

Like Trump, Cohn was the product of an outer-borough arriviste family – in his case, Bronx Jews who made it in banking. He was born in 1927, the only child of Albert, a high-ranking judge, and Dora, a ‘dumpy’ and ‘bulbous’ heiress and generally malevolent matriarch who is blamed for Cohn’s vicious sense of entitlement. ‘Dora made Roy a spoiled brat,’ complains one cousin.

Cohn was just twenty-three when Julius and Ethel Rosenberg were arrested for spying on behalf of the Soviet Union. The well-connected young lawyer landed a role as assistant prosecutor on the case, helping engineer a favourable judge and pushing for the death sentence. This was applied to Ethel too, despite her limited role. In Tony Kushner’s play Angels in America, Cohn is haunted by Ethel’s ghost. In reality, there is a indication he felt remorse. ‘Introspection was overrated,’ writes Bird. ‘Just move on.’

Cohn could absorb documents with preternatural speed, but he wasn’t interested in legal complexities, merely how to manipulate the courtroom. ‘Give me the judge,’ he liked to say. ‘Roy only had two books in his office,’ quipped the lawyer Alan Dershowitz. ‘He had a checkbook, and he had a Rolodex.’

Having helped dispatch the Rosenbergs, he took a position as lawyer and fixer for Senator Joe McCarthy, pipping a young Bobby Kennedy to the role. Cohn genuinely loathed communism and felt the ends of McCarthyism justified the means. But he also enjoyed life as ‘McCarthy’s Rasputin’, courting the media and taking his close collaborator David Schine on a notorious tour of Europe, during which the pair combed US embassy libraries for ‘subversive’ material.

It all fell apart for McCarthy and Cohn in 1953 when it emerged the latter had been pulling strings to keep Schine out of the draft. This was just the opportunity McCarthy’s enemies had been waiting for and the Wisconsin senator’s spell was finally broken. He turned to drink and died a few years later.

Cohn retreated from Washington to New York and launched himself as a lawyer to the stars: Bianca Jagger, Claus von Bülow, Estée Lauder and half the mob. He helped trim John Gotti’s prison sentence and considered ‘Fat Tony’ Salerno a close pal. ‘Mafia values were his,’ Bird writes. Cohn also had a talent for friendship and could be ‘passionate’ about the people he loved, something the author grudgingly acknowledges.

When Dora died in 1967, Cohn used his inheritance to buy an Upper East Side townhouse which became a law office by day and a bordello by night. He was a big man in the city. At the 21 Club, they always made sure his favourite meal was available: a tin of albacore tuna and a jar of Hellmann’s mayonnaise.

It’s easy to get lost in the dark glamour and audacity of Cohn’s life, but his crimes were not victimless. Bird recounts the story of Richard Kerr, a teenage boy at the Kincora Boys’ Home in Northern Ireland who alleges he was sex-­trafficked to Cohn at the Gritti Palace in Venice. The author also echoes suggestions that Cohn may have been behind the murder of Enrico Mazzeo, a corrupt young civil servant shot by the Mafia in 1983, though the evidence provided is only circumstantial. This is a deeply researched and absorbing book, but Bird’s writing is clouded at times by disgust. Was Cohn capable of such a crime? Quite possibly. But the suggestion of murder needs more corroboration.

Because Cohn’s life has already been picked over for decades, many of this book’s revelations are familiar, so it might have benefitted from a touch more analysis. What actually drove Roy Cohn? Bird never quite decides. His mother taught him selfishness and cruelty. His sexuality clearly unsettled him. He was an attention-seeking narcissist who shared Trump’s sense of being an outsider, a grubby Jew sneered at by the Wasp establishment. But ultimately Cohn comes across as an Iago-like figure, powered by unknowable malice. ‘Roy never analysed himself, he just acted,’ writes Bird. ‘Fundamentally, he was an empty vessel. He had no coherent personal philosophy.’

In a way the villain of this story is New York itself: the self-absorbed snobbery of its old establishment and the venality of its parvenus; its amoral obsession with fame, power and boldface names. Like Trump, Cohn grasped instinctively how to flourish in a town where ‘celebrity … eclipsed decency’ every time. His real superpower was total shamelessness. ‘I have a basic sense of the unimportance of everything,’ he told one interviewer. ‘You live seventy years. Civilisation goes on after you’re gone, so what difference does it make?’

Cohn only made it to fifty-nine, succumbing to AIDS but claiming it was liver cancer. His final instruction to his switchboard operator was to tip off the New York Times about his death. Even beyond the grave, he was still playing the game.