A government official with a top security clearance suddenly had it revoked by presidential edict, after he’d left his position. In a nasty political climate, some of his former colleagues who remained in government service had testified his clearance should be taken away and perhaps should never have been issued in the first place given the questions about the loyalty and patriotism of a man who’d once supported communists. Others, no longer working for the government, testified to his integrity and loyalty.

That’s what happened this month to John Brennan, the CIA chief turned Trump critic who lost his clearance as political payback. And it’s what happened the year before Brennan was even born to the man who’d been called “the most famous scientist in America,” nuclear physicist J. Robert Oppenheimer. Oppy, as he was called, organized and ran the Manhattan Project during World War II, and was the man most responsible for the United States developing an atomic bomb. Yet, in 1954, he was brought before a special hearing of the Joint Committee on Atomic Energy, which heard testimony from Oppenheimer and other colleagues, on whether his security clearance should be renewed. By that that time, he was already working at the Institute for Advanced Study at Princeton University, and was a private citizen.

All the above, of course, has been said about Brennan. The many conservatives who applauded Trump’s decision to punish a critic point to Brennan’s vote in 1976 for the Communist candidate for president, CPUSA chairman Gus Hall, as proof that it was foolish to have ever entrusted him with America’s biggest spy agency. One pro-Trump conservative dubbed Brennan “an anti-American radical.” Another called him a “Commie-lover.”

The historian Gregg Herken, in his book Brotherhood of the Bomb, writes that Oppenheimer had been a member of the Communist Party’s secret “professional section” when he was working at the Berkeley Radiation Lab, but found no evidence that he ever spied for the Soviet Union or sought to hinder American interests. During his security hearing, Oppenheimer strongly denied being an actual CP member but admitted to giving money to many left-wing causes. While his claim was generally accepted, it was also known that he had close relationships with Party members. His physicist brother Frank, whom he hired for the Manhattan Project, was a Party member from 1937 to 1941. A girl friend of his, Jean Tatlock, had also been a Party member, and wrote for its newspaper. After breaking up with her in 1939, he met “Kitty” Puening, a radical Berkeley student whose late husband was a member and who died fighting in The Spanish Civil War. Other Party members close to Oppenheimer were Frank’s wife, his landlady Mary Washburn, and several of his graduate students.

On his security questionnaire, Oppenheimer wrote that he had “been a member of just about every Communist Front on the West Coast.” He subscribed to the CP West Coast newspaper, and at his 1954 hearing, he told the AEC Committee “I was associated with the Communist movement.” Herken concludes that had it been known that he was a CP member himself, he most likely would not have received a clearance and would not have been appointed head of the Manhattan Project. “That,” Herken says, “would have been a showstopper.”

Oppenheimer, already meeting with other scientists being considered to lead the project, always gave what Herken calls “shrewd advice” on technical questions. General Leslie Groves, who was the military’s head of the project and the man who had liaison with the scientists, believed that Oppenheimer was the most qualified to lead the entire endeavor. Ignoring the scientists’ many relationships with Communists, the general appointed him to lead the effort to get a bomb, arguing Oppenheimer’s participation “is absolutely essential to the project.”

As it turned out, Oppenheimer not only was loyal to his country, but reported several Soviet attempts to infiltrate the facility and to try and recruit his assistants and students to see if they would spy. In 1943, for example, he told a security officer, who recorded their conversation, that he knew of two or three attempts, and then said “Of course… it is treasonable.”

In 1946, the Atomic Energy Commission assumed the operations of the Manhattan Project and Oppenheimer served as chairman of its advisory committee to give scientific advice. However, in 1953—in a new anti-Communist post-war political atmosphere and the onset of McCarthyism—Oppenheimer had little chance to work on government atomic programs. AEC head Lewis Strauss told Oppenheimer that with President Eisenhower’s support, his security clearance was revoked on Dec. 21, 1953—one day before it was set to expire. When Oppenheimer protested, he asked for a hearing, and the AEC set up the special commission to hold an investigation. The Commission voted in favor of revoking his clearance.

Oppenheimer’s past Communist associations, however, was not the actual reason for revoking his clearance. This was the excuse to diminish his influence as the U.S. raced to develop a yet more powerful nuclear weapon—the hydrogen bomb. Scientists Edward Teller and Ernest Lawrence, both of whom favored development of the H-bomb, also called “Super,” both favored removing Oppenheimer’s clearance, and Teller testified against him at the hearings. A long letter listing the items Oppenheimer would be asked about included his activity against development of the new bomb, and his opposition to other post-war atomic efforts.

That many top scientists who had worked with Oppenheimer testified on his behalf made no difference. Oppenheimer kept his job at Princeton, but his reputation had been sullied for good. His biographers Kai Bird and Martin Sherwin argued that it put an end to scientists dissenting freely from U.S .policy, and that American liberalism had suffered a major defeat.

A decade later, President John F. Kennedy felt it was time to symbolically right that wrong. Oppenheimer’s long-time foe, Edward Teller, nominated Oppenheimer to receive the Enrico Fermi award in 1963, and Kennedy announced that he would present it himself. It was not to be.

On Nov. 22, the day it was announced, Kennedy was assassinated, and Lyndon B. Johnson, the new president, presented it in Kennedy’s place.