At the federal level, Article I, Section 2, Clause 5 of the Constitution grants to the House of Representatives "the sole power of impeachment", and Article I, Section 3, Clause 6 grants to the Senate "the sole Power to try all Impeachments". In considering articles of impeachment, the House is obligated to base any charges on the constitutional standards specified in Article II, Section 4: "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". (Full text of clauses )
The number of federal officials impeached by the House of Representatives includes two presidents: Andrew Johnson and Bill Clinton; both were later acquitted by the Senate. Additionally, an impeachment process against Richard Nixon was commenced, but not completed, as he resigned from office before the full House voted on the articles of impeachment. To date, no president has been removed from office by impeachment and conviction.
Impeachment proceedings may be commenced by a member of the House of Representatives on her or his own initiative, either by presenting a list of the charges under oath or by asking for referral to the appropriate committee. The impeachment process may be initiated by non-members. For example, when the Judicial Conference of the United States suggests a federal judge be impeached, a charge of actions constituting grounds for impeachment may come from a special prosecutor, the President, or state or territorial legislature, grand jury, or by petition.
The type of impeachment resolution determines the committee to which it is referred. A resolution impeaching a particular individual is typically referred to the House Committee on the Judiciary. A resolution to authorize an investigation regarding impeachable conduct is referred to the House Committee on Rules, and then to the Judiciary Committee. The House Committee on the Judiciary, by majority vote, will determine whether grounds for impeachment exist. If the Committee finds grounds for impeachment, it will set forth specific allegations of misconduct in one or more articles of impeachment. The Impeachment Resolution, or Article(s) of Impeachment, are then reported to the full House with the committee's recommendations.