Trump became Cohn’s client and protégé. They won the case by not losing—by counterattacking, raising phony charges, admitting no wrong. Trump paid careful attention. “Roy would always be for an offensive strategy,” Stone says in the film. “These were the rules of war. You don’t fight on the other guy’s ground; you define what the debate is going to be about. I think Trump would learn that from Roy. I learned that from Roy.”

Jeffrey Goldberg: Donald Trump’s mafia mind-set

In 1953, Harry Truman described McCarthyism as “the corruption of truth, the abandonment of our historical devotion to fair play. It is the abandonment of due process of law. It is the use of the big lie and the unbounded accusation against any citizen in the name of Americanism and security. It is the rise to power of the demagogue who lives on untruth. It is the spread of fear and the destruction of faith in every level of our society.” But even this accurate list of brutal tactics and crushing effects doesn’t quite convey the malevolent quality that hovers over the story of Roy Cohn.

Cohn and Trump embody the Mafia style in American politics. I don’t mean the Sopranos; I mean the cold will to power that carries a threat of murder without shame. (Cohn was accused of being responsible for the death by fire of a crewman on his yacht in an insurance plot; like so many other charges, this one was never pinned on him.) There’s a soft spot in American life for this type. He’s admired in mob movies, in war movies (George C. Scott as General George S. Patton: “Americans have never lost and will never lose a war, because the very thought of losing is hateful to Americans”), in sports (Al Davis, the owner of the Oakland Raiders: “Just win, baby”), in entertainment (Jay-Z: “I never prayed to God, I prayed to Gotti / That’s right, it’s wicked, that’s life, I live it / Ain’t asking for forgiveness for my sins”).Two people interviewed in Where’s My Roy Cohn? describe Cohn with the word “evil.” The film shows the Mafia style as it recurs in modern American politics—a kind of metaphysical spirit that inhabits different characters at different times, always identifiable by the dead eyes.

Whenever the Mafia style seems about to die, it turns out to be unkillable. McCarthy met his fate in 1954, when he took on the United States Army in hearings watched by 20 million Americans. The public was new to television and hadn’t seen the Republican senator’s tactics before—the bullying, the lies and smears. When McCarthy went after a young lawyer who’d been on the staff of the Army counsel, he didn’t see the trap that was about to spring. Joseph Welch, the Army’s special counsel, who had hired the young lawyer and was distressed to hear him needlessly maligned, interrupted: “Until this moment, Senator, I think I never really gauged your cruelty or recklessness.” Cohn saw the danger; he shook his head and motioned for McCarthy to stop, but McCarthy kept pressing, until Welch finally said, “Let us not assassinate this lad further, Senator. You’ve done enough. Have you no sense of decency, sir, at long last? Have you left no sense of decency?”