What role does the Senate play in an impeachment trial and possible removal?

1. The Senate is the constitutional courtroom: authority and basic mechanics

Article I assigns the Senate the exclusive responsibility to try impeachments, and when sitting for that purpose senators must be "on Oath or Affirmation," with the Chief Justice presiding in presidential trials—constitutional text that establishes the Senate as the final, political tribunal for impeachment ^{[1] [3]}. The House presents "articles of impeachment" and sends managers to prosecute before the Senate, and the Senate conducts a trial that culminates in a vote on conviction requiring the concurrence of two‑thirds of members present ^{[5] [6] [4]}.

2. The stake: removal and optional disqualification—not criminal punishment

The Senate’s punishment powers are limited: a conviction automatically effects removal from office and the Senate may by separate vote disqualify the individual from holding future federal office, but it cannot impose criminal sanctions—those remain for ordinary courts to pursue later ^{[4] [7] [8]}. The Constitution specifically confines Senate penalties to removal and possible disqualification, and historical practice confirms that criminal liability is distinct from impeachment ^{[9] [7]}.

3. Votes, thresholds and who runs the show

Conviction requires a two‑thirds supermajority of Senators present, an intentionally high threshold the Framers built as a check against partisan removals, and there is no appeal from a Senate verdict—the decision is final within the political-constitutional framework ^{[2] [4] [10]}. While the Vice President normally presides over the Senate, the Chief Justice presides when a president is on trial so the vice president is not placed in the conflict of presiding over a proceeding that could elevate them to the presidency ^{[6] [10]}.

4. Procedure: broad Senate discretion with a few constitutional guardrails

Beyond the oath, the two‑thirds rule, and the Chief Justice requirement, the Supreme Court has held that the Senate has substantial latitude to structure trial procedures and that courts will not second‑guess its methods—Nixon v. United States confirmed the Senate’s procedural discretion and the political question doctrine in this context ^{[3] [2]}. That discretion has produced varied practice: the Senate has formalized rules but also used committees to receive evidence, fashioned trial rules case by case, and can decide to close or open proceedings under its rules ^{[9] [11] [12]}.

5. Roles inside the chamber: managers, defense, and senators as decision‑makers

House managers act as prosecutors presenting the case and evidence to the Senate, the impeached official or counsel presents a defense, and senators function as the triers of fact and law—able to submit questions, call or subpoena witnesses under Senate rules, and ultimately to deliberate and vote ^{[5] [10] [11]}. The Senate’s role thus combines evidentiary fact‑finding, judgment about constitutional standards like "high Crimes and Misdemeanors," and a political judgment about fitness for office ^{[6] [4]}.

6. Historical patterns and practical limits

Historically, convictions in the Senate have been rare—most impeachments have ended in acquittal or other resolutions—with the practical reality that political alignments in the Senate frequently determine outcomes and that the process is separate from criminal courts ^{[13] [7] [14]}. The Senate can remove and optionally disqualify an official, but it cannot hand down fines or imprisonment; those penalties remain within ordinary judicial systems after impeachment if prosecutors pursue them ^{[4] [7]}.