Mitch McConnell has a problem with the facts. The Senate majority leader is taking the position that the evidence presented in the House impeachment inquiry is all the Senate needs to decide whether Trump should be removed from office, and that further testimony from witnesses in the Senate impeachment trial is unnecessary. He has announced that he is in “total coordination” with the White House on the matter and says he has the votes to launch proceedings in the Senate without the commitment to hear from any witnesses. Though senators like Susan Collins have indicated they want to hear witness testimony, McConnell argues that for Republicans to allow new evidence would be “mutually assured destruction” for GOP lawmakers in tight races this year.

There’s just one issue with McConnell’s preferred approach. Unless Republican senators want to accept the facts laid out by the House leadership and restrict themselves to the legal question of whether those facts demonstrate impeachable conduct, they’re going to need to call witnesses.

As many have explained, the House impeachment investigation was analogous to a grand jury investigation, with the resulting impeachment vote akin to a decision to indict. Republicans are now acting as if the House proceedings were a full trial—meaning that the Senate is now acting as an appellate court that can only consider the closed record developed below. Sen. Marco Rubio recently tweeted that the “testimony & evidence considered in a Senate impeachment trial should be the same testimony & evidence the House relied upon when they passed the Articles of Impeachment.”

But the text of the Constitution, the Senate’s own powers and the weight of history all demonstrate that this is wrong. The impeachment clauses mandate that the Senate must conduct a trial—and while impeachment proceedings are not exactly a trial as would occur before a court, the principles of both criminal and civil law provide useful guidelines for how the Senate should act to fulfill its constitutional responsibility.

The Constitution is clear: The Senate has “the sole Power to try”—not review—“all Impeachments.” Unlike an appeals court, the Senate’s powers are not limited to review and remand; instead, it alone has the power to determine whether an impeached president should be punished by removal from office and disqualification from “any Office of honor, Trust or Profit under the United States.” These are powers reserved for trial, not appellate, courts.

Senate Republicans’ logic implies that the trial has already occurred: In this reasoning, the House found Trump guilty and imposed on him the punishment of impeachment. But that cannot possibly be the case, because the Constitution explicitly reserves to the Senate the ability to punish someone who has been impeached with removal from office and, possibly, disqualification from holding future office. The very fact that the Senate is granted the authority to impose punishment on Trump means that the Senate cannot be an appellate court, which would generally be limited to reviewing and remanding a case back to a trial court—in this case, the House.

What’s more, the two times in history that a presidential impeachment has reached the Senate, the chamber has treated it as a trial. The Senate proceedings in Andrew Johnson’s case included the testimony of 25 witnesses for the prosecution and 16 for the defense. During the impeachment of Bill Clinton, the Senate deposed three witnesses—even after the extended independent counsel investigation that preceded the Senate trial. In fact, the Senate has obtained testimony from witnesses in every impeachment trial held in the past 50 years.

To be sure, there are times when even a trial court can decide to render judgment without hearing all the evidence. Motions to dismiss can be brought in both criminal and civil trials. Additionally, criminal cases sometimes have directed verdicts, while judges can issue summary judgments in civil cases. Unfortunately for Senate Republicans, these are not helpful analogs if they wish to avoid hearing from witnesses in the Trump impeachment.

Directed verdicts occur only after the prosecution has presented all its evidence and witnesses and made all its arguments. At that point, the judge can make a ruling based on the evidence provided by the prosecution after determining that a jury would not reach a different conclusion as to culpability. But this doesn’t apply in the current scenario of Trump’s impeachment, in which the House managers will act as the prosecutors before the Senate. The evidence presented in the House was not all the evidence available: President Trump blocked several witnesses from testifying, and at least one of those witnesses, John Bolton, has indicated his willingness to appear before the Senate. It’s more appropriate, therefore, to have a full trial, in which both sides would be able to call witnesses and provide evidence both included in the House impeachment record and new information that has come to light.

As for summary judgments, courts can grant these before trial “if the movant shows that there is no genuine dispute as to any material fact.” In making a summary judgment determination, the court reviews the record in the light most favorable to the non-moving party—that is, the party that wants to proceed to trial. Here, that would be the House through its managers.

The House proceedings presented abundant evidence that Trump used the power of his office and U.S. aid money to extract a personal political favor from a foreign leader. If the Senate wanted to proceed as if this were a summary judgment matter, it would have to assume that those facts were all true. Senators couldn’t claim, for example, that the investigation was for legitimate reasons, not a personal, political favor. Nor could they claim that the scheme was at the direction of the president’s aides, rather than at his personal direction. The question would have to be whether, as a matter of law, a president can turn foreign policy to his own personal political interests—with Republicans having to argue that this is acceptable behavior.

Similarly, a motion to dismiss also requires the assumption that all the alleged facts are true. In either legal analog, even if the Senate Republicans voted to truncate the trial, Trump would not be vindicated. There would be no opportunity to rebut the House’s contentions.

Yet Trump has stated repeatedly that he wants to be defended on the facts, that his call with the Ukrainian president was “perfect,” that he is not satisfied with a defense of “this was bad but not impeachable.” And during the impeachment process in the House, in committee hearings and on the House floor, Republicans repeatedly insisted that there were genuine disputes of material fact at issue over Trump’s conduct toward Ukraine. They argued that the record was inconclusive when it came to Trump’s motivations, whether Ukraine felt pressured, whether there was a quid pro quo and whether any harm was done.

These arguments don’t just undermine Senate Republicans’ attempts to suggest that there are no material factual disputes for trial. They also undermine McConnell’s efforts to adopt the rules governing the Clinton impeachment trial, under which the Senate agreed to begin the trial and make determinations about witnesses at a later point. When the Senate unanimously adopted the Clinton rules, there was no dispute as to the underlying facts set out in the independent counsel’s report and the House record. President Clinton himself had acknowledged both having an affair and lying about it, and he had apologized publicly for his transgressions. The only question for the Senate was a question of law: Was this impeachable conduct? The White House even offered to stipulate to the House record if no witnesses were called in the Senate trial. Even then, the Senate allowed House managers to obtain video depositions from Monica Lewinsky, Clinton’s friend Vernon Jordan, and his aide Sidney Blumenthal, and viewed excerpts of those depositions during the trial.

The essential choice facing the Senate is this: Concede the facts presented in the articles of impeachment in the House and limit the Senate “trial” to the legal question of whether such conduct should be allowed, or let the House managers call witnesses and present evidence and allow the president’s lawyers to dispute that evidence.

Writing about impeachment in the Federalist Papers, Alexander Hamilton recognized that “there will always be the greatest danger that the decision [of whether to convict or acquit a president] will be regulated more by the comparative strength of parties, than by the real demonstrations of innocence or guilt.” The Founders considered many options for the trial of an impeached public figure, but, as Hamilton described, in the end they determined “the Senate the most fit depositary of this important trust,” reasoning that senators “will be most inclined to allow due weight to the arguments which may be supposed to have produced [the trial].”

If Senate Republicans vote against impeachment without considering evidence or hearing from witnesses, they will be betraying this trust. The Constitution anticipates strong political passions; but those passions ought not eclipse the Constitution and the duty it entrusts to the Senate to conduct a fair trial.