Back in the 1980s, when he burnished his reputation as 'Mr Untouchable' — a fearless and incorruptible young prosecutor on a mission to purge New York of organised crime — Rudy Giuliani used public humiliation as a key weapon in his armoury.
Before arresting some Mafia boss or Wall Street shark, he would tip off the local media so their cameras could capture the suspect's downfall as he was frogmarched, handcuffed and wearing prison clothes, into the courthouse.
Now used routinely to shame and discredit major U.S criminals, this tactic is known as the 'perp walk'.
How ironic, then, that 'Rudy the Rock' — as he became known later when, as New York's mayor, he unflinchingly steered the city through the horror of 9/11 — now finds himself ridiculed as the latest fall guy of Sacha Baron Cohen, the man who has turned public humiliation into an excruciating art form.
Actress Maria Bakalova, 24, plays Sacha Baron Cohen's temptress 'daughter' Tutar Sagdiyev who is supposedly aged only 15
Reprising his Kazakh character Borat for a film that premieres on Amazon Prime tonight, Cohen returns to America on an ill-disguised mission to make utter fools of leading Republicans ahead of next month's presidential election — only this time he is accompanied by his temptress 'daughter', Tutar Sagdiyev.
Supposedly aged only 15, in reality she is a hitherto unknown 24-year-old Bulgarian actress and classical flautist named Maria Bakalova, who accentuates her alluring pout with cherry-red lipstick, wears figure-hugging mini-dresses and knows just when to flutter her false eyelashes.
Posing as a naive Right-wing journalist, she secures an interview with Giuliani, now 76, who as Trump's personal lawyer and mouthpiece has become a key figure in the election campaign.
For reasons best known to himself, he agrees to meet her — alone — in a swanky Manhattan hotel suite.
Their encounter, which encompasses almost eight minutes of the film, is so appallingly cheesy and compromising that at times it is difficult to watch.
It beggars belief that a statesman of Giuliani's experience and standing could allow himself to be so well and truly suckered.
Before making her entry, Tutar swigs a miniature liqueur from the suite's fridge, gazes self-admiringly into the mirror and tosses her platinum tresses.
Then she flounces into the room, reclines in an armchair conveniently close to the grinning Giuliani — who wears a stars-and-stripes badge in the lapel of his suit — and begins the entrapment.
Baron Cohen must have been surprised by the ease with which the actress snared her prey.
When she confesses her nerves at meeting one of her 'greatest heroes', he leans forward and grasps both her hands.
'You relax. You want me to ask you the questions?' he jokes, leering at her.
Rudy Giuliani (pictured with Donald Trump in 2005) finds himself ridiculed as the latest fall guy of Cohen
Even when she presents him with a gift — a book containing some sordid- looking pictures — Giuliani doesn't smell a rat.
She starts by asking him about China's role in the pandemic. Giuliani's response is straight from the Trump playbook: 'China manufactured the virus and let it out, and deliberately spread it all around the world.'
He laughs: 'I don't think it came from bats! Did you ever eat a bat?'
They giggle some more, and Giuliani draws out a red handkerchief and dabs the sweat from his chin before praising the President for saving 'a million lives' by his supposed early and astute management of the contagion.
Moments later they clink glasses, he remarks on how good she looks and — after a bizarre intervention by Baron Cohen, posing as a Kazakh film technician — she suggests they have a drink in the bedroom.
Much to the Democrats' glee, the ensuing scene has gone viral, sparked feverish debate on U.S. news channels and — surely as Baron Cohen intended — thrust his mockumentary movie into the heart of the election campaign.
In the eyes of millions of Americans, it also completes the downfall of Giuliani, whose star has been waning for years by dint of his increasingly extreme views, alleged political chicanery and a personal life that hardly squares with his virtuous image.
The film sequence will have been edited to cause Trump's chief fixer maximum embarrassment, of course.
Yet what we appear to see is a seedy and rather pathetic old man only too willing to succumb to seduction by a nubile femme fatale.
First he seems to toy with the neckline of Tutar's powder-blue dress, patting her on the small of her back.
'You can give me your phone number and address,' he soothes — a rather odd remark to make to a young female journalist, you might think.
Then, as she stands over him, Giuliani lies back on the bed and seems to put his hand down his suit trousers.
Whereupon Baron Cohen, now back in his role as the girl's father, bursts into the room dressed as a woman, screaming: 'She is 15, she's too old for you!'
It is only at this late stage that Giuliani flees.
As he does so, Baron Cohen regales him that Trump will be furious with him for leaving the hotel without taking a 'golden shower' — a reference to a disgusting sex act in which the President was alleged to have partaken on a trip to Moscow.
Trump has denied that it ever took place.
Yesterday, Giuliani, too, was in full denial mode. In a flurry of tweets, he branded the film 'a complete fabrication', saying he had simply been 'tucking my shirt in after taking off the recording equipment' when his hand appeared to wander.
He added: 'At no time before, during or after the interview was I ever inappropriate. If Sacha Baron Cohen implies otherwise, he is a stone-cold liar.'
Whatever the truth, this sordid and unedifying episode has dealt Giuliani's reputation a blow from which he might never recover.
And it is a reputation he has spent a lifetime cultivating.
Born into an Italian immigrant family and raised in the mean streets of Brooklyn, his father served time in New York's notorious Sing Sing prison for armed robbery before emerging to run a Mafia loan-sharking and gambling racket.
One of his uncles was also a Mob enforcer with a penchant for breaking the legs of anyone who crossed him. The young Giuliani swore to follow a different path, and at 20 he went on a retreat with a view to becoming a Roman Catholic priest.
Not for the first time, however, his fate was shaped by his love of women. According to long-standing family friend Father Alan Paca, he refused to take the vow of celibacy.
'It was an issue he just couldn't get over,' he says. 'He was always a ladies' man.'
Instead, Giuliani pursued a career in law, and — with his clean-cut image and an almost pious zeal to fight crime — he rose quickly through the ranks, becoming No 3 in the Justice Department in 1981, soon after Ronald Reagan took office.
Along the way he switched political allegiance from Democrat to Independent and then Republican — a move born of expediency rather than ideology, according to his critics.
Giuliani first crossed my radar in 1987, after I became a New York correspondent.
When I arrived, the city and neighbouring towns in New Jersey were run by five Mafia families but soon the young public prosecutor had smashed their empire and put their godfathers in jail for a collective total of 100 years.
He also nailed Ivan Boesky, the Wall Street insider trader who amassed $100 million (£76 million) and was branded the world's wealthiest white-collar crook.
The Untouchable myth grew after he was elected mayor of the Big Apple in 1994.
Then, the city was rife with crack addicts, muggers, panhandlers and prostitutes — but within a couple of years it was safe to walk the streets at night.
Credit for this remarkable transformation was given to Giuliani; though in truth it was the 'zero tolerance' policy of his pioneering police commissioner, Bill Bratton, that made New York one of America's safest cities.
Never shy of self-promotion, however, the mayor took the plaudits. And in September 2001, after the Twin Towers fell, he was for ever at Ground Zero, sleeves rolled-up, defiant messages at the ready, standing shoulder-to-shoulder with the rescuers.
As George W. Bush floundered, this was his finest hour. He became known as 'America's mayor' and, at times, seemed to be leading the entire country in the War on Terror. Surely, it seemed, his journey would end at the White House.
However, his political ambitions began to crumble when he fought Hillary Clinton for a seat in the Senate.
Having divorced his first wife years earlier, on the strange grounds that she was his second cousin, he became embroiled in a bitter divorce wrangle with his second, the mother of his two children, who went on TV to accuse him of being unfaithful.
Amid this spat, Giuliani contracted prostate cancer and bowed out of the Senate race. Though he successfully fought the disease, it was reported to have rendered him temporarily impotent.
In Baron Cohen's new film, Mr Untouchable appears the very picture of health and virility.
Whether he intended to demonstrate that his masculine powers remain undiminished, or was duped into that toe-curling bedroom scene, his judgment has failed him lamentably.