House Speaker Nancy Pelosi (D-Calif.) is holding up a Senate trial until Democrats feel it will be fair.

Senate Majority Leader Mitch McConnell (R-Ky.) isn’t promising what Democrats would call a fair trial, but he’s saying he plans to follow precedent from President Bill Clinton’s impeachment trial about how to decide whether there should be witnesses.

This battle over how to conduct President Trump’s impeachment trial is going into its third week. Here’s how to argue about it like the politicians, with the facts.

If you think the Senate should hear from Trump’s top aides on Ukraine during the trial, point out that:

  • The Clinton impeachment trial featured witnesses.
  • It featured witnesses, even though senators already knew what these witnesses were likely to say because they had been interviewed under oath as part of a two-year special investigation. By contrast, Trump’s former national security adviser John Bolton has indicated he has more to share about Trump and Ukraine than what the House impeachment investigation uncovered.
  • The reason the House didn’t get to talk to Bolton, acting White House chief of staff Mick Mulvaney and two White House aides key to holding up military assistance to Ukraine was because Trump prohibited them from talking. Some of these people even ignored congressional subpoenas. “They are in possession of information that’s directly relevant to the allegations in the articles of impeachment,” a memo from Senate Democrats says.
  • And newly released White House emails further tied Trump’s freeze on Ukraine military assistance to his requests that Ukraine announce investigations into Democrats. The emails came from some of the very White House aides who might be trial witnesses.
  • Hearing from witnesses is the one thing about impeachment on which Americans can agree. A majority of Americans (71 percent), including nearly 64 percent of Republicans, think Trump should allow his top aides to testify, according to a December Washington Post-ABC News poll.

If you don’t think the Senate needs to hear from witnesses, point out:

  • There are no rules that say the Senate has to hear from witnesses. The Constitution says only that the Senate shall conduct a trial. The Senate rules about how to do an impeachment passed in the 1980s don’t mention witnesses — they leave it to the current Senate to decide.
  • McConnell isn’t explicitly ruling out witnesses, though that’s his unstated goal. Instead, the Senate Republican plan technically follows the precedent set by Clinton’s impeachment trial: Senators will vote on the general parameters of a trial to get it started. After opening arguments and written questions by senators, they’ll vote on whether to lengthen the trial and hear witnesses. Senators in the Clinton trial ultimately voted for witnesses, but the vote was along party lines, with Democrats trying to protect their president. Why shouldn’t Republicans be able to do the same?
  • It’s unreasonable to expect Senate Republicans to dig into allegations against the president by inviting new, potentially damaging evidence against him. That’s just not the way politics operates. If Democrats really wanted to talk to these witnesses, they could have held off impeachment for months until the courts forced them to talk. “Due process is not supposed to be easy,” McConnell said on the Senate floor recently.

In fact, a 2000 book about the Clinton impeachment trial revealed that some Senate Democrats and Clinton were constantly talking with each other during his Senate trial. (Though this point requires additional context. The trial was largely seen as a bipartisan effort to be as fair as possible, and Democrats weren’t the ones in control of the process — Republicans were.)

  • Senators take an oath of impartiality at the beginning, but there’s no way to enforce that because it’s a subjective measure. The Senate is a political body. If the Founders wanted this to be completely impartial, they would have required that the judicial system decide the president’s fate. “We all know how this is going to end,” McConnell said on “Fox and Friends” during the holiday break.

That might sound cynical, but it’s the main thrust of McConnell’s argument about how to conduct a Senate trial. Everyone knows Trump is going to be acquitted anyway by the Republican-controlled Senate, so why bother?

Whatever you argue, be wary of saying history is on your side.

The “this is the way it’s done” argument is flimsy because we’ve only had one Senate impeachment trial in the modern era. (The other, for Andrew Johnson, was more than 150 years ago.)

The Fix’s bottom line

McConnell is setting up the Senate trial to leave out any new information about Trump and Ukraine. It’s very difficult for Democrats to expect him to pick up the investigatory work, especially when it could be damaging to Trump.