The impeachment process against Richard Nixon was initiated by the United States House of Representatives on October 30, 1973, during the course of the Watergate scandal, when multiple resolutions calling for the impeachment of President Richard Nixon were introduced immediately following the series of high-level resignations and firings widely called the "Saturday Night Massacre". The House Committee on the Judiciary soon began an official investigation of the president's role in Watergate, and, in May 1974, commenced formal hearings on whether sufficient grounds existed to impeach Nixon of high crimes and misdemeanors under Article II, Section 4, of the United States Constitution. This investigation was undertaken one year after the United States Senate established the Select Committee on Presidential Campaign Activities to investigate the break-in at the Democratic National Committee headquarters at the Watergate office complex during the 1972 presidential election, and the Republican Nixon administration's attempted cover-up of its involvement; during those hearings the scope of the scandal became apparent and the existence of the Nixon White House tapes was revealed.
Following an April 1974 subpoena from the Judiciary Committee, edited transcripts of 42 taped White House conversations relevant to the Watergate cover-up were finally made public by Nixon. However, the committee pressed for the audio tapes themselves, and subsequently issued subpoenas for additional tapes, all of which Nixon had refused. That same month, Nixon also refused to comply with a subpoena from special prosecutor Leon Jaworski for 64 Watergate-related tapes. Ultimately, on July 24, 1974, the United States Supreme Court issued a unanimous decision against Nixon, which ordered him to comply. On May 9, 1974, formal hearings in the impeachment inquiry of Nixon began, culminating on July 27–30, 1974, when members of the Democratic-led Judiciary Committee eventually approved three articles of impeachment. These articles charged Nixon with: (1) obstruction of justice in attempting to impede the investigation of the Watergate break-in, protect those responsible, and conceal the existence of other illegal activities; (2) abuse of power by using the office of the presidency on multiple occasions, dating back to the first year of his administration (1969), to unlawfully use federal agencies, such as the Internal Revenue Service and the Federal Bureau of Investigation, as well as establishing a covert White House special investigative unit, to violate the constitutional rights of citizens and interfere with lawful investigations; and (3) contempt of Congress by refusing to comply with congressional subpoenas. These articles were reported to the House of Representatives for final action, with 7 of the committee's 17 Republicans joining all 21 of its Democrats in voting in favor of one or more of the articles. Two other articles were debated in committee but were rejected. Based on the strength of the evidence presented and the bipartisan support for the articles in committee, House leaders of both political parties concluded that Nixon's impeachment by the full House was a certainty if it reached the House floor for a final vote, and that his conviction in a Senate trial was a distinct possibility.