The American people expect the Senate to conduct a fair impeachment trial, and rightly so. The responsibility to conduct a trial that could result in the removal of a president from office is among the most important responsibilities the Constitution places in the hands of the members of the Senate and the Chief Justice of the Supreme Court, who presides over the process. Each member and the Chief Justice will soon take an oath to “do impartial justice according to the Constitution and laws.” That is an oath they must take seriously.

Considering the removal of a sitting president has been, and should continue to be, a rare event, though it is not an anti-democratic one. Rather, an impeachment trial is the constitutional process our founders created for addressing abuses of power that threaten our democracy. The framers of the Constitution recognized the value of strong executive powers, and they vested them in a single, elected official: the President of the United States of America. But the framers also feared that an individual elected to that office might use its extraordinary powers for his or her own benefit, such as preserving and perpetuating his or her own political power. By giving Congress a special, constitutional process for terminating a presidency, the founders hoped to prevent the democracy they established from becoming the monarchy they despised.

An impeachment trial is a unique constitutional proceeding that has no equivalent, but it is helpful to think of the Senate as serving two familiar roles: judge and jury. As a jury, the Senate has the ultimate responsibility of determining whether the president committed treason, bribery, or high crimes and misdemeanors, and whether those impeachable acts require the removal of the president (and potentially his or her disqualification from future office). As a judge, the Senate has the responsibility of ensuring that the trial serves to elucidate the answers to these questions in a fair, impartial manner. Critically, these two roles are related: The Senate’s ability to do impartial justice when it acts as a jury depends in part on its ability to manage the trial as a judge.

If the Chief Justice and the members of the Senate uphold their obligation to do impartial justice according to the Constitution and laws, there are simple ways for them to ensure that President Donald Trump’s impeachment trial is serious and fair.

First, the Senate should hear the full case before voting on the president’s removal. That means permitting the House of Representatives to present and establish its case for the president’s removal, including subpoenaing witnesses to testify about the president’s misconduct. Although the Senate can and should hear evidence that the House has already gathered, it can and should also seek testimony from senior administration officials like Office of Management and Budget Director and Acting White House Chief of Staff Mick Mulvaney and former National Security Advisor John Bolton who have first-hand knowledge of the president’s abuses of power. During President Bill Clinton’s impeachment trial, the Senate subpoenaed and received testimony from three witnesses. Disposing of Trump’s case without seeking to ascertain the truth would be a sure sign Senators are not following through on their oath to do impartial justice.

Second, the Senate must ensure that the president’s counsel does not turn the trial into a circus by introducing evidence that is irrelevant or that is calculated to confuse the issues. Although the Senate does not have its own rules of evidence, the Federal Rules of Evidence include an impartial, nonpartisan framework for determining whether evidence should be admitted. In short, evidence or testimony is relevant only if it is probative—meaning it “has any tendency to make a fact more or less probable than it would be without the evidence”—and it is material—“the fact is of consequence in determining the action.” Even if evidence is both probative and material, it can still be excluded if “its probative value is substantially outweighed by a danger of one or more of the following: unfair prejudice, confusing the issues, misleading the jury, undue delay, wasting time, or needlessly presenting cumulative evidence.” Furthermore, the Rules state that “when the relevance of evidence depends on whether a fact exists, proof must be introduced sufficient to support a finding that the fact does exist.”

A judge applying these principles would be unlikely to permit Trump’s counsel to seek open-ended testimony from former Vice President Joe Biden’s son Hunter –a tactic the president has said he might employ. Why? Hunter Biden cannot offer testimony that is material to the abuses of power of which Trump is accused. Hunter Biden has no personal knowledge of Trump’s solicitation of Ukraine’s interference in the 2020 election and or Trump’s direction that the entire executive branch engage in “unprecedented, categorical, and indiscriminate defiance” of congressional subpoena power. Even if Trump wanted to use Biden’s service on the board of Burisma, a Ukrainian gas company, to bolster an affirmative defense that he was engaging in a sincere effort to combat corruption in Ukraine, Trump’s counsel would have to establish a factual predicate for that theory. To date, that claim has not been substantiated. Even then, it is very likely that the probative value of Hunter Biden’s testimony would be outweighed by multiple dangers, including confusing the issues, undue delay, and wasting time.

These principles have been enforced with varying degrees of success in previous impeachment trials. The floor trial proceedings in the impeachment trial of Clinton will no doubt loom large, and it is important to draw the right lesson from that episode. Although the record contains strikingly few evidentiary objections and votes to resolve them, that does not mean that principles of relevance played no role. In reality, there was little need for the Chief Justice and the Senate to resolve evidentiary disputes because both the House managers and the counsel for the president presented arguments that squarely addressed the factual and legal merits of impeachment rather than testing the boundaries of what was relevant. If the parties in Trump’s trial do not act in good faith, the Senate and Chief Justice will have to take a more active role policing evidentiary questions to ensure that the trial will reflect the solemnity of the occasion and help the Senate do impartial justice.

Finally, it is lamentable that something so straightforward needs to be said, but doing impartial justice requires that each senator remains impartial. In recent days, several members of the Senate have made statements promising the opposite. Sen. Lindsey Graham (R-S.C.) told CNN, “I am trying to give a pretty clear signal I have made up my mind. I’m not trying to pretend to be a fair juror here.” Senate Majority Leader Mitch McConnell (R-Ky.) told Fox News that he is in “total coordination” with the White House. “I’m not [an] impartial juror,” McConnell told the press on Tuesday, “I’m not impartial about this at all.”

These statements are a cynical betrayal of the Senate’s solemn responsibility. They are particularly cynical in light of the fact Trump was impeached by the House for doing what the founders most feared—abusing the powers of his office for his personal political gain. Before a citizen is impaneled on a jury, he or she is asked whether he or she is willing to decide the case on the basis of the evidence presented. A senator who cannot abide by the same standard should recuse himself.

A fair trial is never a self-fulfilling prophecy. It demands the good faith of the parties to the process, active management of the case that each side makes, and impartial consideration of the evidence that is heard. The American people deserve an impeachment trial that is fair and serious. The Chief Justice and the members of the Senate should deliver one.

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