What is the Senate's role in impeachment?

The Senate has the sole power to try impeachments, meaning the Senate holds a trial to determine whether to convict and remove federal officials who have been impeached by the House of Representatives. This power is set out in Article I, Section 3 of the Constitution. The Senate's role in impeachment is judicial, similar to a jury in a criminal trial, though the Senate is not bound by the rules of evidence used in court. Senators sit as jurors and decide whether the evidence presented justifies removing the impeached official from office.

The Constitution requires that the Chief Justice of the United States preside when the President is on trial. The Constitution does not specify who presides for other officials; in practice, the Vice President presides if available, or the President Pro Tempore of the Senate. House managers present the case for conviction; the impeached official, represented by attorneys, presents the defense. The trial includes opening arguments, presentation of evidence, witness testimony in some cases, and closing arguments. Senators ask questions in writing through the presiding officer.

After deliberations, senators vote on each article of impeachment. Conviction requires a two-thirds vote of senators present, the same supermajority threshold used for treaty ratification, constitutional amendments, and overriding presidential vetoes. If convicted on any article, the official is removed from office. The Senate can also bar the convicted official from ever holding future federal office, by a separate simple-majority vote following conviction.

The Senate has tried 21 impeachments throughout American history, with eight convictions, all of federal judges. No President has ever been convicted in an impeachment trial. Andrew Johnson was acquitted in 1868 by a single vote (35-19, one short of the 36 needed for conviction at the time). Bill Clinton was acquitted in 1999 (45-55 on perjury, 50-50 on obstruction of justice). Donald Trump was acquitted twice, in 2020 (48-52 on abuse of power, 47-53 on obstruction of Congress) and 2021 (57-43 on incitement of insurrection, ten short of the two-thirds threshold). One Cabinet official, Secretary of War William Belknap, was tried by the Senate in 1876 and acquitted, though many senators argued that he could not be convicted because he had already resigned.

The Senate has held that it has power to try impeached officials even after they have left office, an issue that became prominent in the second Trump impeachment trial. The Senate's role in impeachment is one of the most consequential responsibilities the chamber holds. The two-thirds threshold for conviction makes removal extremely difficult, requiring broad bipartisan agreement. The framers designed it this way to ensure that impeachment remained a serious remedy, used only when truly warranted.