Similar to the British system, Article One of the United States Constitution gives the House of Representatives the sole power of impeachment and the Senate the sole power to try impeachments. Unlike the British system, impeachment is only the first of two stages, and conviction requires a two-thirds vote. Impeachment does not necessarily result in removal from office; it is only a legal statement of charges, parallel to an indictment in criminal law. An official who is impeached faces a second legislative vote (whether by the same body or another), which determines conviction, or failure to convict, on the charges embodied by the impeachment. Most constitutions require a supermajority to convict. Although the subject of the charge is criminal action, it does not constitute a criminal trial; the only question under consideration is the removal of the individual from office, and the possibility of a subsequent vote preventing the removed official from ever again holding political office in the jurisdiction where he was removed. Impeachment with respect to political office should not be confused with witness impeachment.
 Impeachable offensesEdit
In the United States, impeachment can occur both at the federal and state level. The Constitution defines impeachment at the federal level and limits impeachment to "The President, Vice President, and all civil officers of the United States" who may only be impeached and removed for "treason, bribery, or other high crimes and misdemeanors". Several commentators have suggested that Congress alone may decide for itself what constitutes an impeachable offense. In 1970, then-House Minority Leader Gerald R. Ford defined the criterion as he saw it: "An impeachable offense is whatever a majority of the House of Representatives considers it to be at a given moment in history." Four years later, Ford would become president when President Richard Nixon resigned under the threat of impeachment.
Article III of the Constitution states that judges remain in office "during good behaviour", implying that Congress may remove a judge for bad behavior via impeachment. The House has impeached 14 federal judges and the Senate has convicted six of them.
 Officials subject to impeachmentEdit
The central question regarding the Constitutional dispute about the impeachment of members of the legislature is whether members of Congress are officers of the United States. The Constitution grants the House the power to impeach "The President, the Vice President, and all civil Officers of the United States."  It has been suggested that members of Congress are not officers of the United States. Others, however, believe that members are civil officers and are subject to impeachment.
The House of Representatives did impeach a senator once: Senator William Blount, in 1798. The Senate expelled Senator Blount and, after initially hearing his impeachment, dismissed the charges for lack of jurisdiction. Left unsettled was the question whether members of Congress were civil officers of the United States. The House has not impeached a Member of Congress since Blount. As each House has the authority to expel its own members without involving the other chamber, expulsion has been the method used for removing Members of Congress.
Jefferson's Manual, which is integral to the Rules of the House of Representatives, states that impeachment is set in motion by charges made on the floor, charges preferred by a memorial, a member's resolution referred to a committee, a message from the president, charges transmitted from the legislature of a state or territory or from a grand jury, or from facts developed and reported by an investigating committee of the House. It further states that a proposition to impeach is a question of high privilege in the House and at once supersedes business otherwise in order under the rules governing the order of business.
The impeachment process is a two-step procedure. The House of Representatives must first pass by a simple majority articles of impeachment, which constitute the formal allegation or allegations. Upon their passage, the defendant has been "impeached". Next, the Senate tries the accused. In the case of the impeachment of a president, the Chief Justice of the United States presides over the proceedings. For the impeachment of any other official, the Constitution is silent on who shall preside, suggesting that this role falls to the Senate's usual presiding officer. This may include the impeachment of the vice president, although legal theories suggest that allowing a defendant to be the judge in his own case would be a blatant conflict of interest. If the Vice President did not preside over an impeachment (of anyone besides the President), the duties would fall to the President pro tempore of the Senate.
To convict the accused, a two-thirds majority of the senators present is required. Conviction automatically removes the defendant from office. Following conviction, the Senate may vote to further punish the individual by barring him from holding future federal office, elected or appointed. Conviction by the Senate does not bar criminal prosecution. Even after an accused has left office, it is possible to impeach to disqualify the person from future office or from certain emoluments of his prior office (such as a pension). If there is no charge for which a two-thirds majority of the senators present vote "guilty", the defendant is acquitted and no punishment is imposed.
 History of Federal Impeachment Proceedings in the United StatesEdit
Congress regards impeachment as a power to be used only in extreme cases; the House has initiated impeachment proceedings only 64 times since 1789 (most recently against Judge Thomas Porteous of the United States District Court for the Eastern District of Louisiana), and only the following 19 federal officials have been under threat of impeachment by congress (and some of them have been impeached):
- Two presidents:
- Andrew Johnson, Democrat, was impeached in 1868 after violating the then-newly created Tenure of Office Act. President Johnson was acquitted by the Senate, falling one vote short of the necessary 2/3 needed to remove him from office, voting 35-19 to remove him. The Tenure of Office Act would later be found unconstitutional by the Supreme Court of the United States in dicta.
- Bill Clinton, Democrat, was impeached on December 19, 1998, by the House of Representatives on articles charging perjury (specifically, lying to a federal grand jury) by a 228–206 vote, and obstruction of justice by a 221–212 vote. The House rejected other articles. One was a count of perjury in a civil deposition in Paula Jones's sexual harassment lawsuit against Clinton (by a 205–229 vote) and an article which accused Clinton of abuse of power by a 48–285 vote. President Clinton was acquitted by the Senate on February 12, 1999. The Senate vote fell short of the necessary 2/3 needed to remove him from office, voting 45-55 to remove him on obstruction of justice and 50-50 on perjury.
- One cabinet officer, William W. Belknap (Secretary of War). He resigned before his trial, and was later acquitted. Allegedly most of those who voted to acquit him believed that his resignation had removed their jurisdiction.
- One Senator, William Blount, in 1797. He was expelled by the Senate, which declined to try the impeachment.
- One Justice of the Supreme Court of the United States, Samuel Chase in 1804. He was acquitted by the Senate.
- Fourteen other federal judges, including Alcee Hastings, who was impeached and convicted for taking over $150,000 in bribe money in exchange for sentencing leniency. The Senate did not bar Hastings from holding future office, and Hastings won election to the House of Representatives from Florida. Hastings's name was mentioned as a possible Chairman of the House Permanent Select Committee on Intelligence, but was passed over by House Speaker-designate Nancy Pelosi, presumably because of his previous impeachment and removal. Source U.S. Senate
Richard Nixon, Republican, was never impeached. While the House Judiciary Committee did approve articles of impeachment against him and did report those articles to the House of Representatives, Nixon resigned before the House could consider the impeachment resolutions and was subsequently pardoned by President Ford, although this would have had no binding effect on the impeachment proceedings.