"The principle that senators are not jurors in the traditional sense was well established at the outset of the 1999 impeachment trial of President Bill Clinton."

"Tasked with delivering an opening statement for the House managers, who present the House’s case to the Senate, Rep. Robert Barr, R-Ga., reminded the senators of Clinton’s tendency to 'nitpick' over details or 'parse a specific word or phrase of testimony.' To Barr, the conclusion was obvious: 'We urge you, the distinguished jurors in this case, not to be fooled.' That was the moment Sen. Tom Harkin, an Iowa Democrat, had been waiting for. 'Mr. Chief Justice,' he said, addressing William Rehnquist, who was presiding over the trial, 'I object to the use and the continued use of the word "jurors" when referring to the Senate.'... The chief justice sustained the objection. 'The Senate is not simply a jury,' he ruled. 'It is a court in this case.' Rehnquist thus admonished the House managers 'to refrain from referring to the Senators as jurors.' For the balance of the trial, they were called 'triers of law and fact.'... In an ordinary trial, the jury’s role is generally limited to fact finding, while the judge determines the scope and application of the law. In an impeachment trial, however, the Senate itself has the 'sole power' to decide every issue. Recognizing the Senate’s all-encompassing responsibility, and his own limited role, Chief Justice Rehnquist referred to himself throughout the proceeding only as 'the chair.'"

Writes lawprof Steven Lubet in (The National Interest).