Those who crave seeing President Trump convicted by the Senate, or who even hope for the semblance of a serious impeachment trial, now find themselves tempted to indulge in romance-novel-level fantasies about the role of the chief justice. In this imaginary version of impeachment, Chief Justice John G. Roberts Jr. will exercise authority to call witnesses and otherwise insist on a proceeding whose outcome is not a foregone conclusion.

I regret to inform you: This is a delusion, if a pleasant one. The chief justice is not going to arrive on a white steed to save the country from Trump. Indeed, a minimalist approach on Roberts’s part is not only the all-but-certain outcome — it is also the wiser course, better for the court and the country.

In the case of a presidential impeachment, the chief justice plays the role of a constitutionally designated stand-in. The Constitution assigned this role to the chief justice in part, as Yale Law School professor Akhil Reed Amar has noted, to “mark these impeachments as hugely distinct from all others, calling for special solemnity.” But the more fundamental reason is that the vice president, who presides over other impeachment trials, suffers from an obvious conflict of interest in overseeing any trial whose outcome could elevate him to the presidency.

As Justice Joseph Story explained in 1833, the choice of chief justice was “not founded on any supposition, that the chief justice would be superior in confidence, and firmness, and impartiality . . . but on the necessity of excluding the vice president from the chair.” The chief justice does only what the vice president would do in the case of a lesser impeachment.

Which is to say: not that much. The Senate’s standing rules on impeachment provide that the presiding officer “shall direct all the forms of proceedings” during an impeachment trial. Specifically, the presiding officer has power to “rule on all questions of evidence including, but not limited to, questions of relevancy, materiality, and redundancy of evidence.” This sounds like a lot, except when you get to later in the relevant sentence: “ . . . which ruling shall stand as the judgment of the Senate, unless some Member of the Senate shall ask that a formal vote be taken.”

In other words, any evidentiary ruling by the chief justice is subject to review by the Senate — and subject to override by a majority of senators. Not only that, but the chief justice can punt from the start: “he may at his option, in the first instance, submit any such question to a vote of the Members of the Senate.” As University of Missouri law professor Frank Bowman has noted, “Unlike in an ordinary trial, there is no higher court to which such a senatorial judgment can be appealed.” Instead, this is a trial with 100 judges, who get to decide for themselves all kinds of issues ranging from the burden of proof to what constitutes a high crime or misdemeanor.

One potential wrinkle involves whether the chief justice, as presiding officer, can break a tie if the Senate were to split 50-50 on some question. Imagine, for example, the Senate dividing on the question of whether to subpoena former national security adviser John Bolton — or whether the president could assert executive privilege to block Bolton’s testimony. Precedent suggests that Roberts could — but does not have to — break the tie.

Chief Justice Salmon P. Chase, presiding over the trial of President Andrew Johnson in 1868, demanded the authority to rule on issues relating to the admissibility of evidence and to cast tie-breaking votes; he ended up doing so twice. Then again, Chase is hardly the best role model for an impartial presiding officer. As historian Brenda Wineapple recounts, Chase “feverishly sought the presidency” himself even while conducting the impeachment trial and had made his disdain for the articles of impeachment clear.

Chief Justice William H. Rehnquist, presiding over the trial of President Bill Clinton in 1999, took a far more hands-off approach. The closest Rehnquist came to a substantive ruling was when Iowa Democrat Tom Harkin objected to House managers calling the senators “jurors.” Rehnquist sided with Harkin, concluding that “the Senate is not simply a jury; it is a court in this case.” After the trial had ended, Rehnquist spoke with satisfaction about his limited role. “I did nothing in particular, and I did it very well,” Rehnquist said, citing a favorite line from Gilbert and Sullivan.

Everything in Roberts’s background and worldview suggests he will adopt a similarly restrained approach. Yes, Roberts was moved to rebuke the president after Trump assailed an “Obama judge” for ruling against the administration. But that was in service of Roberts’s goal to keep the federal judiciary from being perceived as just another partisan institution. Injecting himself into the guts of the impeachment would work against that goal.

And there would be dangers in an activist, hands-on chief justice presiding. Imagine if Rehnquist, named to the Supreme Court by one Republican president and elevated to chief justice by another, had ruled repeatedly against a Democratic president. Imagine if Roberts, denounced by Trump during the 2016 campaign as a “disgrace” and a “disaster,” ruled in ways harmful to this president. The Constitution assigns Roberts a role in the impeachment trial, but he would be best advised to play that role in a way that keeps him as much out of the substance — and therefore the muck — of impeachment as possible.

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