<P> Impeachment in the United States is an enumerated power of the legislature that allows formal charges to be brought against a civil officer of government for crimes alleged to have been committed . Most impeachments have concerned alleged crimes committed while in office, though there have been a few cases in which Congress has impeached and convicted officials partly for prior crimes . The actual trial on such charges, and subsequent removal of an official upon conviction, is separate from the act of impeachment itself . Impeachment proceedings have been initiated against several presidents of the United States . Andrew Johnson and Bill Clinton are the only two presidents to have been successfully impeached by the House of Representatives, and both were later acquitted by the Senate . The impeachment process against Richard Nixon was never completed, as Nixon resigned his office before the vote of the full House for impeachment, but such a vote was widely expected to pass, and the threat of it and a subsequent conviction in the Senate was the impetus for Nixon's departure . To date, no U.S. President has been removed from office by impeachment and conviction . The impeached official continues in office until conviction . </P> <P> Impeachment is analogous to indictment in regular court proceedings; trial by the other house is analogous to the trial before judge and jury in regular courts . Typically, the lower house of the legislature impeaches the official and the upper house conducts the trial . </P> <P> At the federal level, Article Two of the United States Constitution states in Section 4 that "The President, Vice President, and all civil Officers of the United States shall be removed from Office on Impeachment for, and conviction of, Treason, Bribery, or other High Crimes and Misdemeanors ." The House of Representatives has the sole power of impeaching, while the United States Senate has the sole power to try all impeachments . The removal of impeached officials is automatic upon conviction in the Senate . In Nixon v. United States (1993), the Supreme Court determined that the federal judiciary cannot review such proceedings . </P> <P> Impeachment can also occur at the state level: state legislatures can impeach state officials, including governors, in accordance with their respective state constitutions . </P>

Who has the authority to try impeachment cases