The Constitution authorizes the House to impeach — and the Senate to try and convict — federal officials including presidents, judges, and cabinet officers for "Treason, Bribery, or other high Crimes and Misdemeanors." A simple majority impeaches in the House; conviction in the Senate requires a two-thirds supermajority. Conviction removes the officer; the Senate may additionally bar them from future office.
Modern impeachments — of Andrew Johnson, Bill Clinton, and Donald Trump (twice) — have all ended in acquittal. Many federal judges have been impeached and removed. The two-thirds threshold means that absent extraordinary cross-party agreement, conviction is effectively impossible, raising the question of whether impeachment remains a viable check or only a symbolic one.
Debates today center on what conduct qualifies as "high crimes and misdemeanors" — whether non-criminal abuse of power qualifies; whether late impeachments survive a former officeholder; how partisan polarization affects the Senate's deliberative function; and whether procedural reforms could restore the process's seriousness.