Final answer:
The Senate's ability to try all impeachments is stipulated in Article I, Section 3, Clause 6 of the U.S. Constitution. This section grants the Senate the sole power to conduct impeachment trials, requiring a two-thirds majority for a conviction, and the Chief Justice presides when the President is being tried.
Step-by-step explanation:
The section of Article I in the U.S. Constitution that discusses the Senate's ability to try all impeachments is located in Section 3, Clause 6. The clause explicitly states that "The Senate shall have the sole Power to try all Impeachments", meaning that when a civil officer, including the President, is impeached by the House of Representatives, the Senate takes on the role of conducting the trial. It's important to note that for a conviction to occur, there must be a concurrence of two-thirds of the Senators present during the trial.
Moreover, when the President is on trial, the Chief Justice of the Supreme Court presides over the proceedings.
Additionally, the Senate can invoke another section, Article I, Section 3, Clause 7, which allows for the disqualification of a convicted individual from holding future federal office.
Historical instances, such as the impeachment trials of both Andrew Johnson and Bill Clinton, saw the Senate not convicting the accused presidents, who completed their terms in office. However, other officials and judges have been removed from office through this impeachment process.