Conventional wisdom on the role of the chief justice in the impeachment of the president is that he is bound by Senate rules and maintains almost no independent responsibility to ensure fairness. That hands off view is based largely on Senate tradition and on how William Rehnquist handled his duties in the impeachment of Bill Clinton when there was agreement on the applicable procedures. However, the Senate trial is not simply a battle between the House and the president. Rather, the American people need to be sure that justice is done, and to achieve that, there are certain concrete steps that the chief justice can and should take during the trial.

Under the Constitution, the vice president presides over the Senate. In an impeachment trial of the president, however, that role is assigned to the chief justice. So although there are no written records for that important change, the substitution assures the public that the vice president would not make rulings that seem to favor his boss, or that would influence the trial in a way that might make his ascension to the Oval Office more likely.

An impeachment trial is not a criminal trial, but that does mean that the Senate may utilize procedures that violate due process. To prevent that from happening, the chief justice plays a critical role in ensuring basic fairness for everyone. Suppose the House decided to prove its factual case through live witnesses, and the Senate rules did not permit cross examination. In that case, the chief justice should not allow the rights of the president to be seriously undermined because the Senate rules so provide. The Framers almost certainly chose the chief justice to preside over the trial not just because they wanted a neutral officer who ensures fairness, but also because they did not want him to be, in the words of Brendan Sullivan when he had represented Oliver North, a potted plant.

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The same approach should be applied within the situation more likely to occur in this impeachment. The House wishes to submit testimony from witnesses who did not show before its hearings, but the Senate rules do not provide for that. Because due process is a two way street, the chief justice could properly insist that the Senate must have a good reason for not allowing the House to obtain additional testimony because the trial is not just a contest between the House and the president, but a good faith effort to determine whether Donald Trump Donald John TrumpObama calls on Senate not to fill Ginsburg's vacancy until after election Planned Parenthood: 'The fate of our rights' depends on Ginsburg replacement Progressive group to spend M in ad campaign on Supreme Court vacancy MORE should continue in his office. Indeed, this is a decision that will affect every American in this country.

Then there is the matter of juror bias, either for or against conviction. In one sense there is nothing to be done here since there are no alternates eligible to serve in the Senate. Moreover, the chief justice cannot change the views of those who have already made up their minds. But if perfect justice through impartial jurors is unattainable, at least the appearance of a lack of bias is possible. At the start of the trial, the chief justice should therefore request, surely nothing more, that jurors refrain from making any public statements about the possible outcome of the trial so that the proceedings are not seen as a charade leading to a foregone conclusion.

During this trial, the principal issue is not likely to be what the president actually did, but whether his conduct rises to the level of an impeachable offense. Were this an ordinary federal trial, the judge would instruct the jury on the applicable law, but there are no such instructions applicable here. Nonetheless, it would not be appropriate for the chief justice to lay out his views on the law of impeachment and advise the Senate as such.

Rather, the chief justice should provide time for both the House and the president to provide the Senate their views on the law of impeachment as applied to the facts. In that way, the Senate and the American people can be given what are likely to be two competing visions of the applicable law of impeachment and then make their independent judgments as to the validity of those contentions and, in the end, the decision of the Senate.

The chief justice would almost certainly prefer not to have the formidable assignment of presiding over this impeachment trial, however, that is the command of the Constitution. It means that he should carry out his duties with the goal of providing justice to the president, the House, the Senate, and the American people, not feeling bound by the wishes of the parties.

Alan Morrison is a professor who teaches constitutional law and the Lerner Family Associate Dean of Public Interest at George Washington University.