Article I, Section 3, Clause 7:
Judgment in Cases of Impeachment shall not extend further than to removal from Office, and disqualification to hold and enjoy any Office of honor, Trust or Profit under the United States: but the Party convicted shall nevertheless be liable and subject to Indictment, Trial, Judgment and Punishment, according to Law.
The immediate effect of conviction upon an article of impeachment is removal from office,1 although the Senate may subsequently vote on whether the official shall be disqualified from again holding an office of public trust under the United States.2 If this latter option is pursued, a simple majority vote by the Senate is required.3 If not, an individual who has been impeached and removed may remain eligible to serve in an office in the future, including as a Member of Congress.4
By design,5 impeachment is separate and distinct from a criminal proceeding. Impeachment and conviction by Congress operates to remove an individual from office; it does not, however, preclude criminal consequences for an individual's actions.6 Those who have been impeached and removed from office are still subject to criminal prosecutions for the same underlying factual matters, and individuals who have already been convicted of crimes may be impeached for the same underlying behavior later.7 A number of federal judges, in fact, have been indicted and convicted for conduct which has formed the basis for a subsequent impeachment proceeding.8
The text of the Constitution does not address the sequencing of impeachment and other legal proceedings. Generally speaking, historical practice has been to impeach individuals after the conclusion of any related criminal proceedings, although this might simply reflect practical convenience as such proceedings can alert Congress of improper behavior that may warrant impeachment. Nonetheless, nothing in the Constitution demands this order of events.
The Constitution bars the President from using the pardon power to shield individuals from impeachment or removal from office.9 A President could pardon impeached officials suspected of criminal behavior, thus protecting them from federal criminal prosecution; such a move would not, however, shield those officials from removal from office via the impeachment process.