Here’s are the key questions—and experts’ best guess at the answers. The short answer is: it’s complicated.

The House managers’ hopes of winning 51 votes in favor of calling witnesses at the Senate impeachment trial of President Donald Trump seem all but dashed.
But what if they eke out a bare 50-50 tie? In that case, they would retain a reed-thin chance of prevailing. But the prospects are uncertain, and some possible scenarios are downright bizarre.
“To be honest, I just don’t know how a tie would play out,” impeachment historian Frank O. Bowman told Newsweek in an email. Bowman, a professor at the University of Missouri School of Law, is the author of High Crimes and Misdemeanors: A History of Impeachment for the Age of Trump.
On a tie vote, the House managers’ last-gasp hope would be for Chief Justice John Roberts, Jr., to cast a tie-breaking vote in their favor. But can he? Would he? And what if he even did?
Here’s are the relevant questionsand experts’ best guess at the answers. The short answer is: it’s complicated.
Can Chief Justice John Roberts, Jr., cast a vote in the event of a tie?
It’s possible. But while some scholarslike Bowman and former Acting Solicitor General Walter Dellingerbelieve he may or even probably has that power, others, like Garrett Epps of the University of Baltimore, doubt that he does. And unless Roberts thinks his role leaves him no choice but to cast such a vote, he seems temperamentally unlikely to thrust himself voluntarily into this partisan mess.
Here’s the ambiguity. What the Constitution says explicitly (Article I, Section 3, Clause 4) is that the vice president, when sitting as president of the Senate, can cast a vote when the chamber is “equally divided.” It also says (Article I, Section 3, Clause 6) that when the Senate is sitting in an impeachment trial concerning the president of the United Statesas opposed to, say, a lesser federal officer or federal judgethe chief justice of the United States “shall preside.” Most people assume the Framers of the Constitution substituted the chief justice for the vice president in that situation because the vice presidentbeing next in line to assume the Presidency if the impeachment is successfulwould have a colossal conflict of interest.
But those sparse sentences leave room for confusion. To some readers, it only stands to reason that the chief justice, when presiding over the Senate, should have the same powers that the vice president can exercise when the Senate sits in legislative session, including the power to cast a tie-breaking vote. But the Constitution never explicitly says that. And since the Constitution also says (Article I, Section 2) that the Senate “shall have the sole power to try all impeachments,” it’s possible that the Framers would not have wanted to give the chief justicewho is not a senatorsuch decisive power. So it’s unresolved.
But didn’t Chief Justice Salmon Chase cast several tie-breaking votes in the impeachment trial of Andrew Johnson in 1868?
He did. So there is that historical precedent, if Chief Justice Roberts chooses to avail himself of it. But, according to Ira Goldman, who has schooled himself in the arcana of Senate Parliamentary rules (he was counsel to former Republican Senator Pete Wilson of California from 1983 to 1991), the Senate itself does not regard the Chase case as an institutional precedent. That’s because no Senator challenged Chase’s votes with a formal “point of order.”
I thought the Senate affirmed Justice Chase’s votes.
It’s complicated. After one of Chase’s tie-breaking votes, his authority to cast such votes was challengedthree timesby certain senators at the Johnson trial. Each effort failed. One senator proposed, for instance, a rule change that would have specified that the chief justice “is not a member of the Senate, and has no authority under the Constitution to vote on any question during the trial.” The proposed amendment was defeated. Nevertheless, the Senate itself does not regard these failed rule-makings as binding precedents, according to Goldman.
In 1974, for instance, in anticipation of the possible impeachment trial of President Richard Nixonone that, because of Nixon’s resignation, never came to passthe Senate Rules committee drafted proposed standing rules for impeachment. At an executive session the specific issue arose of whether the chief justice could vote in tie-break situationsnotwithstanding the Justice Chase precedents of 1868.
A consensus could not be reached. The Senate Parliamentarian at the time, Dr. Floyd Riddick, expressed the view that the Constitution gave the chief justice that right. But Senator Robert Byrd thought the chief justice should vote only on procedural matters (like admissibility of evidence), and not on substantive questions (like whether, upon conviction, to disqualify the impeached officer from ever holding federal office again). Finally, the chairman of the committee, Senator Howard Cannon, insisted that the chief justice should not be permitted to vote “under any circumstances” because he was not a “member of the Senate.”
In the end, they punted, omitting a reference to the issue in the standing rules. These proposed rules later formed the basis for the current standing rules, which were passed in 1986. They remain silent on that issue.
Don’t the standing rules actually give the Chief Justice the right to subpoena witnesses on his own?
That view was advanced in a New York Times op-ed by a former Acting Solicitor General, a Georgetown Law professor, and a former Republican Congressman. The authors focused on Rule V of the standing rules, which says the presiding officerthe chief justice during a presidential impeachmenthas the power “by himself” to issue “all orders … authorized by these rules or by the Senate.”
Goldman contends that the op-ed authors are misreading the rules. “Rule V is subject to Rule VI,” he says, and Rule VI explains that it’s only “the Senate” that has the power to “compel the attendance of witnesses.” Any other reading makes little sense, he argues. The “presiding officer” in a non-presidential impeachment could be any senator filling in as President of the Senate pro temporeeven a lowly freshman, he observes. The rules could not have contemplated giving that one person, acting on his own, the power to issue subpoenas.
The Senate report for the 1986 standing rules seems to lend some support for Goldman’s view. It says that Rule V simply authorizes the presiding officer “to issue Senate processes and to enforce Senate regulation and orders”making it sound as thought he’d be carrying out the will of the Senate rather than substituting his for theirs.
If Chief Justice does choose to vote, can the Senate overrule him?
Yes, but that’s when things could get really, really strange. That’s because the outcome of the votelikely to be 50-50, againcan depend on how the question is phrased.
“Say the chief justice breaks a tie,” voting for witnesses to be subpoenaed, Goldman says, playing out the first scenario. (Remember, the general rule is that a majority vote is required, so ties lose.) “Someone can make a point of order: ‘[The chief justice] has no right to do that,'” Goldman says. The chief justice rules on the point of order, finding that he does have the right to vote. Someone appeals the chief justice’s ruling to the Senate. The question is then posed: “Shall the ruling of the [chief justice]”i.e., that he has the right to vote”be sustained as the position of the Senate?” On a 50-50 vote, the chief justice’s ruling would not be sustainedi.e., he has no right to cast the voteand so no witnesses would be called.
But under another scenario, with the same 50-50 vote, the witnesses could be called. That scenario plays out this way: When a senator objects to the chief’s casting of a vote, the chief makes no ruling and, instead, immediately submits the appeal to the Senate. “Then the question is: Is the point of order well taken?” Goldman explains. Now, on a 50-50 vote, the point of order fails, so the chief justice’s vote counts.
Theoretically, we could even find ourselves in an infinite regress situation. For instance, in the first scenario, after the Senate votes 50-50 on whether to sustain chief justice Roberts’ ruling on the point of order, what if the chief justice votes to break that tie, toobootstrapping himself into being able to vote? And on it goes. But given what we know of Roberts, that scenario is virtually inconceivable.
Is it absolutely clear that the Vice President has no vote?
This brings up the last scenario, the wackiest of all. It’s not an “absurd” possibility, Goldman says, though it might be “absurdist.”
Remember that during the Andrew Johnson impeachment, there was no sitting vice president. (Johnson had been vice president and ascended to the presidency upon Lincoln’s assassination, leaving the vice presidency vacant.) So this issue did not arise.
As the Bill Clinton impeachment trial approached, Goldman says, Vice President Al Gore raised the possibility of participating in some manner. But Sen. Byrd told him not to.
Still, what if President Trump sent Vice President Pence to the Senate floor? In the case of a 50-50 vote on witnesses, Pence could cast the tie-breaking voteciting Article I, Section 3, Clause 6preempting the possibility of the chief justice casting the critical vote. Then the outcome would depend on whether the chief justice permitted Pence’s vote, and on the phrasing of the ensuing points of orders.
Given the uncertainties in the rules, and the level of partisanship in play, this last scenario would be “wild, but not outrageous,” says Goldman.