Mr. and Mrs. Scriber had differing opinions over whether the Senate was obliged, by law or by custom, to try an impeachment case brought by the House. The bottom line is that the constitution grants the Senate the power to do so but does not command a trial.
Informing that opinion I turned to Lawfare where I found Bob Bauer, former White House Counsel to President Obama, in a January 2019 opinion, asking Can the Senate Decline to Try an Impeachment Case?.
The Constitution does not by its express terms direct the Senate to try an impeachment. In fact, it confers on the Senate "the sole power to try,” which is a conferral of exclusive constitutional authority and not a procedural command. The Constitution couches the power to impeach in the same terms: it is the House’s “sole power.” The House may choose to impeach or not, and one can imagine an argument that the Senate is just as free, in the exercise of its own “sole power,” to decline to try any impeachment that the House elects to vote.
Moreover, Senate Republicans could act procedurally to block a trial. Bauer continues.
The Senate has options for scuttling the impeachment process beyond a simple refusal to heed the House vote. The Constitution does not specify what constitutes a “trial,” and in a 1993 case involving a judicial impeachment, the Supreme Court affirmed that the Senate’s “sole power” to “try” means that it is not subject to any limitations on how it could conduct a proceeding. Senate leadership could engineer an early motion to dismiss and effectively moot the current rule’s call for the president or counsel to appear before the Senate. The rules in place provide at any rate only that “the Senate shall have power to compel the attendance of witnesses”: they do not require that any other than the president be called. Moreover, the Senate could adjourn at any time, terminating the proceedings and declining to take up the House articles. This is what happened in the trial of Andrew Johnson, in which the Senate voted on three articles and then adjourned without holding votes on the remaining eight.
This discussion does not engage in depth with all the parliamentary possibilities and intricacies. But it is sufficient to say for present purposes that, if the House of Representatives were to impeach the president, Senate Republicans would be in a position, if so inclined, to scuttle any trial.
Of course, this might never come to pass. If Trump were to be impeached, the evidence for his removal from office could turn out to be so overwhelming that it would be politically untenable for McConnell to adopt this course or impossible for him to hold his caucus in line. These outcomes are particularly likely if public opinion at the time swings decisively against the president. Or alternatively, one might hope the Republican leader retains institutional instincts that would kick in and lead him to follow Senate rules and precedent.
But he might not. Republicans have laid the groundwork for rejecting the legitimacy of a House impeachment. The president and his party’s leadership and supporters have repeatedly and vociferously characterized the strong Democratic criticisms of Trump as infected to the core by unremitting partisanship, personal hatred, an unrelenting refusal since Election Day to accept the result of the 2016 election and unlawful or unethical conduct by the Department of Justice, the FBI, the special counsel and the press. And whatever evidence eventually surfaces, Senate Republicans have already shrugged off the president’s appearance in a successful criminal prosecution as “Individual 1,” an allegedly active participant in a conspiracy to violate the campaign finance laws. As the debate over impeachment process plays out over 2019, and as the 2020 presidential campaign already underway intensifies, those advancing this case may argue for letting the voters decide.
All of this may seem academic in the extreme when the House has yet to even initiate an impeachment inquiry. But the country could see a rapid move toward an impeachment and, most predictably [now that] the special counsel [has concluded] his investigation, an accelerated process in the House toward that end. It may not be too soon to ask McConnell and his Republican colleagues whether they support the Senate’s duty to try in full a House impeachment of Donald Trump, in conformity with current rules.
The only way a trial might be forced is for an impeachment inquiry to provide public compelling evidence of high crimes and misdemeanors. More and more House Democrats are tilting that way.