Three or four?

It’s a question being hotly debated as House Speaker Nancy Pelosi (D-Calif.) prepares to transmit the articles of impeachment against President Trump to the Senate for trial.

Will it take four Republican senators to buck Majority Leader Mitch McConnell (R-Ky.) and force the Senate to consider additional testimony and documents? Or could the votes of just three Republicans — bolstered by Chief Justice John G. Roberts Jr. — do the trick?

The answer to the question hinges on the role of the chief justice, who the Constitution specifies shall “preside” over the trial.

The practical stakes of the debate are huge. McConnell, who seeks the quickest possible exoneration of Trump, has done an impressive job of corralling his caucus. But at least three Republican senators — Mitt Romney (Utah), Lisa Murkowski (Alaska) and Susan Collins (Maine) — have expressed reservations about stiff-arming testimony from former national security adviser John Bolton and others that would be plainly relevant to the allegations in the articles of impeachment.

Collins on Friday revealed that she is working with a “fairly small group” of senators to ensure that the trial rules allow for witnesses on both sides.

Were these three — or any three — to hold firm to the common-sensical position that the Senate and the American people need to hear the evidence before deciding the case (and were no Democrat to defect, which itself is uncertain), the count would stand at 50-50.

In any other setting besides the trial of the president, a 50-50 Senate tie would be broken by the vice president, who under Senate rules occupies the position of “presiding officer” in an impeachment trial. But the chief justice fills that role in the case of a presidential impeachment, which raises questions about whether he should behave any differently.

Many have argued that the chief justice will play a strictly honorary role at the trial, with no substantive input whatsoever. Under this view, the 50-50 tie would equate to a “no” vote, since the motion failed to gain a majority. Therefore, any effort to add to the evidence would require four maverick Republicans to succeed.

Perhaps no actor in Washington is more eager for Roberts’s role to be strictly honorary than Roberts himself. The trial promises to be an unruly political free-for-all governed by demagoguery and raw will, the polar opposite of the decorous world of reason and precedent that prevails across the street at the Supreme Court.

But Roberts might not have the luxury of that choice. Acknowledging that the sparseness of precedent and the primacy of politics inject an element of uncertainty into all predictions of how the trial will unfold, the idea that he will be a robed dignitary with no substantive role to play is tenuous.

In fact, text, structure and history — all the legal tools of the trade — point strongly toward a substantive role at trial for the chief justice.

The Constitution speaks sparingly to the contours of an impeachment trial but specifies unambiguously that the chief justice must “preside.” The Senate rules, which incorporate this command, make no distinction between the chief justice’s role as presiding officer in this context and the vice president’s in all others. There is no apparent reason the presiding officer’s responsibility would include breaking 50-50 ties in one context but not the others.

A presiding officer presides; that means keeping order and moving proceedings along, at least somewhat analogous to the role of a district court judge. The reason the chief justice and not the vice president plays this role in an impeachment of the president alone is that the vice president would have an automatic conflict of interest. If the presiding officer had no substantive role to play, there would be no conflict. It’s precisely because the presiding officer might make substantive decisions that the chief justice must step in.

Finally, the chief justice played a substantive role in both previous impeachment trials of the president. Most notably, Chief Justice Salmon Chase twice broke ties in the Andrew Johnson trial.

For all these reasons, Harvard Law School professor Laurence Tribe told me he “agree[s] strongly that the role is not solely honorific or purely decorative.”

There is one glaring way in which Roberts’s duties will be different from his accustomed judicial role: His rulings are not final. In the Wild West world of the Senate as trier, a majority of the body can always impose its will. And all political precedent indicates McConnell would do exactly that if he felt it served the president’s purposes.

But by the same token, if Roberts casts the 51st vote in favor of, for example, the issuance of a subpoena to Bolton, there is no judicial recourse. (Trump could always try, of course, but the courts would swiftly rebuff him.) And in that event, it’s hard to see where and how the McConnell camp would secure 51 votes to overrule Roberts, whose vote carries an extra measure of stature and authority.

So as the trial looms, we should all be counting to three and in particular keeping eyes (and pressure) on Collins, Murkowski and Romney. They have it in their power to serve up important decisions to Roberts, which as things are developing may be the best the Democrats can hope for.

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