ASHINGTON, May 5 — Fifty years after Senator Joseph R. McCarthy's communist witch hunt, the Senate today made public transcripts of his closed-door questioning of more than 400 witnesses that revealed a calculating side to McCarthy's public persona of a threatening bully who did not hesitate to destroy reputations and lives.

Put simply, the documents show that McCarthy used closed hearings to weed out potential witnesses who defended themselves effectively and instead called to the stand only those who appeared weak or confused.

McCarthy, a Republican from Wisconsin, was chairman of the Senate Permanent Subcommittee on Investigations in 1953 and 1954, at the height of the cold war. He used that position to mount an investigation that came to be widely characterized as a witch hunt for communists in the federal government and beyond.

Documents from closed Senate hearings are sealed for 50 years, and so those were made public today with a new round of pious denunciations from the men and women who run the Senate now. The senators who oversaw the project, Susan Collins, a Maine Republican, and Carl Levin, Democrat of Michigan, made public more than 4,000 pages of transcripts in the same room where McCarthy held many of his hearings.

"We hope that the excesses of McCarthyism will serve as a cautionary tale for future generations," Senator Collins said.

Senator Levin said, "History is a powerful teacher, and these documents offer many lessons on the importance of open government, due process and respect for individual rights." He recalled organizing an anti-McCarthy petition drive as a student at Swarthmore College 50 years ago.

The transcripts show that some witnesses "defended themselves so resolutely or had so little evidence against them that the chairman and council chose not to pursue them," Donald A. Ritchie, the Senate historian who organized the records, said. The closed sessions, he added, served as "as dress rehearsals" for the main show: the televised Army-McCarthy hearings, which sought to show that the Army had been infiltrated by Communists.

As an example, Eslanda Goode Robeson, the wife of the blacklisted singer-actor Paul Robeson, would not answer when asked if she was a member of the Communist Party.

"Under the protection of the fifth and 15th amendments, I decline to answer," she said. The 15th amendment gave blacks the right to vote.

McCarthy responded: "The 15th has nothing to do with it. That provides the right to vote."

Eslanda Robeson said: "I always understood it has something to do with my being a Negro, and I have always sought protection under it."

McCarthy called her to testify.

By contrast, the composer Aaron Copland effectively evaded every question.

McCarthy asked him if he had ever attended a Communist meeting, and Copland answered: "I am afraid I do not know how you define a Communist meeting."

McCarthy: "Have you ever been a communist sympathizer?"

Copland: "I am not sure I would be able to say what you mean by `sympathizer.' "

McCarthy: "Do you feel communists should be able to teach in our schools?"

Copland: "I have haven't given the matter such thought as to give an answer."

Copland was not called to testify, apparently because his testimony would not have made good theater.

During two years, McCarthy held sensational hearings into supposed Communist subversion and espionage in the Department of State, the Voice of America, the United States Information Libraries, the Government Printing Office, the Army Signal Corps and American military-contractor industries among other agencies, an inquiry that culminated with the televised hearings.

The transcripts made public today included testimony by Langston Hughes, James Reston and many obscure government employees and others. McCarthy often hectored his witnesses and showed little regard for their individual rights.

In a news release today, the Senate said McCarthy's closed "executive sessions were held preliminary to the public hearings and were not open to the press or public." But an Army lawyer who attended many of the sessions, John G. Adams, wrote at the time that the closed hearings were actually not nearly so exclusive.

"It didn't really mean a closed session, since McCarthy allowed in various friends, hangers-on and favored newspaper reporters," Mr. Adams wrote. "Nor did it mean secret, because afterwards McCarthy would tell reporters waiting outside whatever he pleased. Basically `executive' meant Joe could do whatever he wanted."

McCarthy called hearings on short notice in Washington, New York, Boston or other cities and was often the only senator in attendance, which was quite unusual. Sometimes he did not show up and left the questioning to his subordinate, Roy Cohn.

The Senate censured McCarthy in December 1954. He lost his seat as chairman the next month, after Democrats regained the majority in the Senate. He died in office a broken man in 1957. He was 47 years old.