Let us first look at the House’s January 13 resolution:

Now let’s read the relevant text of the Constitution:

Some commentators, such as Alan Dershowitz, have attacked this second impeachment of Donald Trump as unconstitutional because it departs from our time-honored values of due process, having been undertaken with no hearings, no witnesses, no testimony and all within the space of a couple of hours on the floor of the House, resembling Dickens’s portrayal of the revolutionary tribunal that condemned Charles Darnay in A Tale of Two Cities. That argument is sound and should be applauded.

True, there are unresolved constitutional questions as to whether the Senate may try an individual who is no longer in office, or whether a disqualification to holding future office may be divorced from removal from office. Some have argued that, with respect to President Trump, the scheduling of the Senate trial after President Joe Biden’s inauguration effectively stopped the process in its tracks, rendering this week’s trial illegitimate.

One need not even raise those questions, however. The critical defect in the Senate’s proceeding with the trial is the absence of the Chief Justice of the United States. We are informed that Senate Majority Leader Chuck Schumer invited Chief Justice John Roberts to preside, but Roberts declined to participate. That decision and the reason for it should settle the issue.

There is an unavoidable either/or here, and the Senate needs to face up to it. Either the impeachment resolution and the subsequent trial are aimed at Donald Trump as president, or it is an impeachment of Donald Trump as a private citizen. These proceedings are obviously the former, since the resolution holds Trump to have violated the presidential oath of office. The argument that “the President” in Article I, Section 3, Clause 6 means only the sitting president does not change that fact. The text clearly refers to the subject of the impeachment at the time of the impeachment. The plain language of the text and the subject of the impeachment resolution indicate that “the President” in question was/is Donald Trump as president, acting as president. And if that is the case, the Constitution makes clear, the Chief Justice must be the one to preside over this impeachment trial.

The general principles behind the complex issue of impeachment require the Chief Justice’s presence as a constitutional prerequisite in a presidential impeachment. No less an authority than Alexander Hamilton, in the 65th essay of The Federalist, makes just this argument. He writes that the difficulty of structuring presidential impeachments so as to be more likely to result in just outcomes acceptable to the American people is mitigated, if not solved, by the Constitution’s making the Chief Justice the “president of the court of impeachments.” That arrangement, he writes, is “perhaps the prudent mean.” Why? Impeachment of the president pits one branch of the government against another; it is Congress versus the president. The only way this can be done consistent with the principles of separation of powers and checks and balances is to have the arbiter of this process be the head of the third and least politically invested branch of government, the Chief Justice. Surely the Constitution’s framers would be shocked to see a fierce partisan of the party opposite that of the impeached president calling balls and strikes—precisely the outcome they intended to avoid by choosing the Chief Justice to preside over presidential impeachments.

Finally, it should be understood, but often is not: constitutional opposition to this impeachment does not imply approval of the speech and actions of Donald Trump up to and including his address to the crowd on the national mall on January 6th. There are constitutional means by which Congress can express disapproval of President Trump’s behavior, including a congressional investigation and a bicameral, bipartisan resolution and censure. What Congress may not do, however, is engage in an illegitimate process that violates the plain language and delicate institutional balance provided by our governing constitutional charter.

Jeffrey J. Poelvoorde is Associate Professor of Politics at Converse College. Bradford P. Wilson is Executive Director of the James Madison Program in American Ideals and Institutions at Princeton University.

The views expressed in this article are the writers’ own.