Editorial: No, you can’t have a serious Trump impeachment trial without witnesses

In a rebuke of historic proportions, the House of Representatives on Wednesday transmitted to the Senate two articles of impeachment, both arising from President Trump’s outrageous attempt to strong-arm Ukraine into investigating former Vice President Joe Biden. Trump is only the third president to be impeached.

Now it falls to the Senate to fulfill its constitutional obligations and ensure that the president receives a full and fair trial. That means putting partisanship aside, taking the allegations against the president seriously and following the facts where they lead.

But for that to occur, some Republican senators will have to strike profiles in courage and demand that witnesses be called as part of the trial. Only four Republican senators need to join the Senate’s Democrats to make that happen without a tie-breaking vote by the chief justice. Four GOP votes would provide a majority sufficient to ensure that subpoenas go out to former national security advisor John Bolton, acting White House Chief of Staff Mick Mulvaney and others with first-hand knowledge of the events in question.

So far, though, only three Republicans have indicated an openness to hearing witness testimony, and even they will be under enormous pressure to fall into line with the White House’s desire for a quick trial ending in acquittal.

If even a few Republicans resist the notion of a trial without witnesses, Senate Majority Leader Mitch McConnell (R-Ky.) will have to do the right thing and treat the allegations against Trump with the seriousness they deserve.

A Republican talking point is that it’s not the Senate’s job to summon witnesses or explore unaddressed lines of inquiry. That, the argument goes, was the House’s job. But that ignores the fact that the White House ordered potential witnesses not to cooperate with House investigators and withheld documents.

Even so, thanks to current and former officials who defied the directive and testified anyway, the House was able to construct a compelling case that Trump perverted U.S. foreign and defense policy for narrow personal and political ends.

Additional testimony at the trial stage is entirely appropriate. Bolton and Mulvaney potentially could offer crucial testimony about whether Trump explicitly tied the announcement by Ukraine of an investigation of Biden to the release of hundreds of millions of dollars in aid to help Ukraine resist Russian aggression.

The conventional wisdom is that the Senate won’t conduct a serious trial, because even Republican senators who are appalled by Trump’s conduct are terrified of alienating the president’s excitable supporters. A few Republican senators can upend that depressing expectation by being true to their oath to do “impartial justice according to the Constitution and laws: So help me God.”