Capitol Hill is the book’s setting for the conversion of political suspicion into official examination. In congressional hearing rooms, questions about scientific work and past associations became tests of loyalty; outside them, the consequences reached careers, families, and the public standing of scientists. The Hill’s marble institutions also appear in sharp contrast with the poverty visible from a committee anteroom, giving the hearings a social landscape as well as a political one.

A place of gathering and apprehension

By the summer of 1948, Capitol Hill had become a source of worry for J. Robert Oppenheimer, then in Europe. The House Committee on Un-American Activities had been holding hearings, and he feared what its investigations might mean for his brother and perhaps for himself. The Alger Hiss case intensified that concern: if a former high-ranking official could be accused of Communist affiliations and brought down, Oppenheimer feared that his brother’s known Party membership could make him vulnerable too. From abroad, he advised his brother to find a lawyer familiar not only with Congress but also with Washington and the press.

The prospect soon became personal. Oppenheimer had received a subpoena to testify before the House Committee on Un-American Activities. He knew that one of its members, Harold Velde, was a former FBI agent who had worked in Berkeley during the war, investigating the Radiation Laboratory. Capitol Hill thus entered the narrative before Oppenheimer’s appearance as a place toward which political anxiety was already directed: the Committee could summon people whose earlier scientific and political lives had seemed far removed from congressional judgment.

Closed doors and public hearings

On June 7, 1949, Oppenheimer appeared before a closed executive session of the House Committee on Un-American Activities. Six congressmen, including Richard Nixon, questioned him over two hours. He appeared ostensibly as chairman of the General Advisory Committee of the United States Atomic Energy Commission, but the questioning focused on alleged atomic espionage and the political histories of scientists. Oppenheimer chose not to bring a personal lawyer; instead, he brought Joseph Volpe, the Commission’s general counsel, and introduced him in that official capacity. He answered cooperatively, denying that he had known before the war that Joseph Weinberg was a Communist.

The closed setting did not keep Oppenheimer’s testimony from having public consequences. Questioned about Bernard Peters, he acknowledged having described Peters to a Los Alamos security officer as dangerous and left-wing. He recounted Peters’s past in the German Communist Party, his opposition to the Nazis, his imprisonment in a concentration camp, and his escape. Oppenheimer appears to have assumed that an executive session would keep his remarks from public view. Once the testimony became known, it damaged his relationship with Peters and became one more episode in the political scrutiny surrounding him.

Six days later, Oppenheimer returned to Capitol Hill for an open hearing of the Joint Committee on Atomic Energy in the Caucus Room of the Senate Office Building. The issue was the export of radioisotopes for research in foreign laboratories. Lewis Strauss, the lone dissenting commissioner in the United States Atomic Energy Commission’s four-to-one decision approving the exports, believed the isotopes could be diverted to military uses. Oppenheimer rejected that concern in deliberately comic terms, arguing that ordinary objects could also be used in atomic-energy work. Laughter from the audience accompanied his testimony; beside him at the witness table, Volpe could see Strauss’s anger. The exchange made a technical dispute into a public confrontation between the two men.

The hearing’s wider human landscape

Capitol Hill’s hearings also pulled Oppenheimer’s brother and Jackie into their orbit. As Jackie waited in a House Committee anteroom, she looked out at the contrast between the government buildings’ marble and manicured grounds and nearby rows of dilapidated houses occupied by Black residents. She saw barefoot children in ragged clothes, apparently undernourished, playing with discarded objects from the street. Her view connected the Committee’s power to summon and question people with a visible inequality beyond its hearing rooms; while she worried about what the Committee would ask, she also grew angry at being called to account as un-American.

Under oath, Oppenheimer’s brother acknowledged that he and Jackie had belonged to the Communist Party for about three and a half years, from 1937 to 1940 or early 1941, and that his Party alias had been Frank Folsom. He refused to identify the political affiliations of friends, maintaining that he would not talk about people he regarded as decent and well-meaning. The contrast with Oppenheimer’s testimony was consequential: the brother held that line against repeated demands to name names. He told reporters that they had joined the Party in response to unemployment and want, had later left disillusioned, and that he knew of no atomic espionage or Communist activity at the laboratories. Soon afterward, the University of Minnesota accepted his resignation as an assistant professor. He had been three months from tenure; after his final meeting with the university president, he left in tears.

From hearing room to national spectacle

The congressional hearings became part of a larger public drama. While waiting for the judgment of the security panel that had heard his case, Oppenheimer and Kitty watched the Army-McCarthy Senate hearings on their black-and-white television. The televised exchanges between Senator Joseph McCarthy and the Army’s counsel brought the spectacle of congressional accusation into their home, echoing the ordeal Oppenheimer had just undergone. Capitol Hill’s investigations were no longer confined to those called before committees: television made their methods and confrontations a national spectacle.

The repercussions also returned to the House itself. When the Commission’s ruling against Oppenheimer was announced on the floor of the House of Representatives, some congressmen stood and applauded. That public response contrasted with the later circulation of the hearing transcript, which exposed the proceeding’s inquisitorial character and helped damage Strauss’s reputation. The book’s Capitol Hill is therefore more than a backdrop for testimony: it is where political scrutiny acquired institutional force, where private and professional histories were made public, and where the conflict over whether scientific advisers could dissent from government policy became visible.