The Supreme Court case hinged on to what extent a president could withhold information from other government branches in the name of privacy, and the stakes for then-President Richard M. Nixon were high.

Seven of Nixon’s closest confidants had been indicted in the Watergate scandal, and the special prosecutor investigating the matter wanted audio recordings of some of the president’s phone conversations from the Oval Office. Nixon claimed executive privilege protected him, and he refused to release the tapes.

“Many people assume that the tapes must incriminate the president, or that otherwise, he would not insist on their privacy,” Nixon said in a speech in April 1974. “But the problem I confronted was this: Unless a president can protect the privacy of the advice he gets, he cannot get the advice he needs.”

The nation’s highest court found that argument inadequate. Speaking to a packed and hushed courtroom on July 24, 1974, Chief Justice Warren E. Burger delivered a 16-minute judgment that Nixon must comply with a trial subpoena for the recordings “forthwith,” The Washington Post reported at the time.

The historic judgment that U.S. presidents do not hold unchecked power to declare executive privilege set a precedent that courts would consider in evaluating whether President Trump could shield his own communications from external scrutiny amid an impeachment inquiry.

Although White House phone calls like the now-famous one between Trump and the Ukrainian president are no longer recorded, House Democrats said Wednesday they planned to subpoena documents related to the conversation. Rep. Elijah E. Cummings (D-Md.) wrote in a memo that the “White House’s flagrant disregard of multiple voluntary requests for documents” made it necessary for him to issue a subpoena. Trump has called the impeachment inquiry a “scam” and wrote that he is “coming to the conclusion that what is taking place is not an impeachment, it is a COUP.”

The Supreme Court’s 8-to-0 ruling on the Nixon tapes came hours before the House Judiciary Committee was scheduled to start debating whether to recommend that the president be impeached for blocking the investigation of the Watergate break-in. Justice William H. Rehnquist had recused himself from the case because of a prior association with former attorney general John N. Mitchell.

Nixon’s attorney James St. Clair had argued that the court had no jurisdiction over the release of the tapes because the conflict between the president and the special prosecutor was internal to the executive branch. The court, however, found that this was a special case because special prosecutor Leon Jaworski was tasked with representing the nation and had the authority to challenge any privilege the White House invoked.

Although the court agreed with Nixon that publishing a president’s conversations with his aides could make it harder for him to get candid advice, the justices said they had to weigh the general privilege of confidentiality against “the fair administration of criminal justice” in a specific case.

“We cannot conclude that advisers will be moved to temper the candor of their remarks by the infrequent occasions of disclosure because of the possibility that such conversations will be called for in the context of a criminal prosecution,” Burger, an appointee of Nixon, said in the court’s opinion.

Privilege exists for information concerning diplomatic or national security secrets, the court ruled, but a federal judge would be able to inspect that material in their chambers to decide what portion of it a prosecutor should have. Nixon had not made a national-security argument related to the 64 conversations — ranging from June 1972 through April 26, 1974 — at issue in his case.

Nixon said he was “disappointed” in the Supreme Court’s decision but would comply. Three days later, the House Judiciary Committee overwhelmingly approved an article of impeachment against him and sent it to the full House.

Nixon then released the tapes, including a recording that is now referred to as the “smoking gun.” That tape revealed that on June 23, 1972, a few days after the Watergate break-in, the president had talked about getting the FBI to stand down on its investigation into the incident.

In a statement accompanying the release of the tapes, Nixon urged people to consider the evidence in its entirety and the events “in perspective.”

“Whatever mistakes I made in the handling of Watergate, the basic truth remains that when all the facts were brought to my attention I insisted on a full investigation and prosecution of those guilty,” Nixon said. “I am firmly convinced that the record, in its entirety, does not justify the extreme step of impeachment and removal of a president.”

On Aug. 8, 1974, Nixon acknowledged he had lost congressional support and resigned before the House could impeach him.

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