According to CNN legal analyst & Supreme Court biographer Joan Biskupic, Supreme Court Chief Justice John Roberts is currently facing the defining moment of his career on the bench as he presides over the impeachment trial of Donald Trump and he needs to give serious thought as to how history will treat him if he allows the Republican Party to brush aside the charges against the president.

With the Republican-controlled Senate expected to vote to block attempts to allow witnesses to appear in the trial — or end in a 50-50 deadlock — it will be up to Roberts to decide if he wants to intercede and keep the trial alive.

“Roberts has led the US Supreme Court for 15 years. Now age 65, he may serve another 15 years as chief justice. But Friday, he could face a moment on the elevated Senate dais that significantly shapes his legacy — if it gets to that point,” she wrote. “The chief justice could be pressed to break a tie vote on whether witnesses will be called. And he will almost certainly face further pleas by Democratic House managers to intervene and require a deeper review of the Trump allegations.”

With Sen. Lamar Alexander (R-TN) coming out against allowing witnesses late Thursday night, the reality of a truncated trial withe the public overwhelmingly wanting witnesses to be called — particularly in light of former national security advisor John Bolton’s Ukraine revelations in his upcoming book — Roberts is the only roadblock that stands between a legitimate inquiry and allowing the president to continue to conduct business in the way he has.

“At the high court, Roberts works away from the clicking cameras. More Americans have no doubt seen more of him this month than they have seen of him at least since 2005, when he appeared before the Senate for his confirmation hearings,” she explained. “During the last nine trial days, Roberts has firmly enforced Senate impeachment rules. He appeared to know all senators by name and state as they asked to be recognized for their respective questions.”

“Now, he could be forced into a more difficult dilemma. As a vote over witnesses nears and the Senate may be evenly divided on the question, Democrats especially have argued that Roberts should be able to break a tie vote<‘s she continued. “When the vice president presides over the Senate, he can cast a vote when the Senate is tied, but that power is specified in the Constitution. For the trial of a President, the Constitution states that chief justice shall preside but does not detail his power.”

Noting that scholars are conflicted on whether Roberts can intercede, Biskupic suggests he could — but may choose not to.

“If presented with a 50-50 split, Roberts could assume voting authority,” she wrote. “Yet, based on Roberts’ trademark caution and use of Rehnquist as a model, he may shun any opportunity to make a real difference in this trial. Roberts would also be mindful that however he responds, his actions would color public regard not only for his stature but that of the federal judiciary.”

“Roberts has worn the heavy mantle of public expectations in his role at the middle of an ideologically divided bench. Through the years, he has disappointed conservatives who wanted the Republican George W. Bush appointee to vote consistently for their side. Roberts has equally frustrated liberals seeking regular replays of his 2012 decisive vote, with the four liberal justices, to uphold the Barack Obama-sponsored Affordable Care Act,” she added, before stating that he has yet to provide a clue how he night rule in the event of a tie.

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