The clamor is growing for Chief Justice John G. Roberts Jr. to take an assertive stance in presiding over the impeachment trial of President Trump. This remains a bad idea — one that would be damaging in the long run to the Supreme Court and the country.

Roberts took the appropriate step, after midnight on the first day of the trial, of admonishing the House managers and the president’s lawyers to tone down the rhetoric after a particularly inflammatory exchange. Both sides, he said, should “remember that they are addressing the world’s greatest deliberative body.”

About that deliberative body: Senators are supposed to be present in the chamber to hear the evidence and arguments. Some have been AWOL. Is Roberts supposed to instruct them to get back in their seats, or else? Come on. This is the U.S. Senate, not a kindergarten class. The chief justice is not there to take attendance.

And that would be, in the view of the “Go Roberts!” crowd, just the start. The president’s lawyers, some argue, misrepresented the evidence — they lied — before the Senate. White House counsel Pat Cipollone, rebutting House manager Adam B. Schiff (D-Calif.), claimed that “not even Mr. Schiff’s Republican colleagues were allowed into the SCIF,” a sensitive compartmented information facility, during the deposition testimony of witnesses before the House Intelligence Committee. Untrue: Republican members of three separate committees were not only permitted to enter, they were given equal time to engage in questioning.

Cipollone asserted that Schiff “manufactured a false version” of Trump’s call with Ukrainian President Volodymyr Zelensky. “He read it to the American people, and he didn’t tell them it was a complete fake,” Cipollone claimed. Untrue, again: Schiff made clear he was characterizing the July 25 call, not quoting verbatim. “Shorn of its rambling character, and in not so many words, this is the essence of what the president communicates,” Schiff said. This kind of blatant mischaracterization is beneath what should be the dignity of the counsel to the president.

But a proper topic for calling-out by the chief justice? Charles P. Pierce of Esquire argues yes. “They are lying to you, Chief,” he wrote. “Be the umpire. Call them out.” This seems like the slipperiest of slopes. The chief justice is going to interrupt the trial to question the veracity of arguments being made by the president’s lawyers? Where would this stop? If it started, wouldn’t the chief justice open himself — and, by extension, the court — to claims, in this trial or, heaven forbid, the next, that he is putting his thumb on the scale for one side or the other? There is a difference between enforcing standards of decorum and opining on matters of substance.

Senators are perfectly capable of judging the veracity of these statements for themselves. The House managers can call Cipollone out. But the chief justice? This would be an aggressive move for a trial court judge in an ordinary case, much less the chief justice presiding over an impeachment trial.

And while the chief justice is a judge, he is not a judge in this situation, nor is it an ordinary trial. As University of North Carolina law professor Michael J. Gerhardt wrote recently in The Post, “The constitutional directive that the chief justice ‘shall preside’ does not mean that he will be a presiding judge. ‘Preside’ must be understood in the context of an impeachment trial, not a trial in a court of law. And impeachment trials are not legal proceedings; they are political proceedings with senators as the ultimate decision-makers.” Gerhardt is no Trump apologist: In testimony before the House Judiciary Committee, he described Trump’s actions as “worse than the misconduct of any prior president."

Those who would like the chief justice to behave more like one of his predecessors, Salmon P. Chase, in the 1868 impeachment trial of Andrew Johnson, would do well to read their history. Chase entertained Johnson at a reception the day before he swore the oath to administer impartial justice at the impeachment trial. And Chase was scheming to run — again — for president even as he presided over the Senate trial; his backers were raising money for his presidential bid. He had a personal interest in seeing Johnson acquitted. He should serve as a caution for Roberts, not an inspiration.

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