The prospect that Roy Moore will be elected the next senator from Alabama despite an increasing number of allegations that he sexually assaulted and “dated” teenagers while he was in his 30s is rightly terrifying. As a result, some Senate Republicans are saying that Moore should be expelled immediately from the chamber if he wins the election so he can be replaced by an alternate. But that prospect is also potentially terrifying: It could hand the White House a way to shut down special counsel Robert S. Mueller III’s investigation. For good.

That possibility arises as the result of the intersection of several somewhat arcane provisions of the Constitution. Begin with the Senate’s power to bar Moore. The Constitution provides that each house of Congress has the power to judge the qualifications of its members. But for good reason, the Supreme Court has said that those qualifications are “fixed” by the Constitution itself: To be in the Senate, Article I, Section 3 says that you have to be 30 years old, a U.S. citizen for nine years and from the state in which you were elected. If the Senate finds that a senator-elect does not meet those qualifications, it can exclude him or her by simple majority vote.

But our founders didn’t want to give members of Congress the power to block duly elected folks for nefarious reasons. (Most poignantly, in the case of former Democratic congressman Adam Clayton Powell of New York, the Supreme Court evidently feared that the attempt to bar him from taking his seat was a plot by white Beltway operatives to undermine the wishes of his Harlem district.) So while the Senate and the House can refuse to seat a member by simple majority vote, they can only do so for reasons laid out in the Constitution: if that person was not duly elected or if he or she fails to meet the qualifications for the chamber to which he was elected.

If Moore does win next month’s special election in Alabama, the Senate has another way to get rid of him: expulsion. Article I, Section 5 says that each house can “with the concurrence of two-thirds, expel a member.” That supermajority requirement is in there for good reason: Again, the founders wanted to avoid self-dealing by folks in Congress.

And some of the scenarios reportedly under consideration in Washington and in Birmingham make clear that this sort of self-dealing could, indeed, be very dangerous. If Moore wins and then is expelled or resigns, the 17th Amendment kicks in, giving Alabama Gov. Kay Ivey (R) the power to appoint an interim senator. Alabama law allows that senator to serve until a special election takes place; the governor decides when the special election takes place, but she can wait as long as she wants before calling one. So if Moore is gone, Ivey can appoint someone to fill the seat for a while.

One of the leading candidates to replace Moore, should it come to that, would have to be none other than the person who was last elected to that very seat: Jefferson Beauregard Sessions III. Sessions, of course, is performing another job right now as attorney general of the United States. And while he has taken a wrecking ball to many of the most time-honored principles of the department, it is what he is not doing (and indeed is unable to do) that raises the biggest concern around his possible return to his old job. Sessions recused himself from the Justice Department’s investigation into Russian attempts to interfere in last year’s presidential campaign and handed the matter over to his deputy, Rod J. Rosenstein, after it came out that Sessions had given inaccurate testimony to the Senate about his meetings with Russian Foreign Minister Sergey Kislyak. Rosenstein, in turn, despite a very shaky start at the department, appointed Mueller to lead the Russia investigation, including whether President Trump’s campaign colluded with Russian operatives, and has since allowed that investigation to proceed independently.

If Sessions returns to the Senate, however, Trump will nominate another attorney general. And you can imagine what kind of litmus test he’d have for his new choice: Trump would want someone willing to shut down the Russia investigation. The president himself has said that he wouldn’t have made Sessions attorney general if he knew that Sessions would recuse from the Russia investigation.

Notably, a new attorney general would not even need to fire Mueller. Mueller serves under regulations that govern the appointment of a special counsel. I had the privilege of drafting those regulations nearly 20 years ago. We all knew at the time that they were the creation of the attorney general, and could therefore be revoked by the attorney general, too. So a new attorney general could simply repeal the regulations. Mueller would go poof, and his investigation would cease. Any facts, prosecutions, and investigative material that Mueller had uncovered would then lie under the supervision of the new appointee, selected by a president who’s been vocal about his objections to Sessions’s recusal. And if you think firing Mueller or repealing the regulations is too much, consider this: the new attorney general could simply say that he doesn’t have the same conflict of interest as Sessions did and assert that he can do Mueller’s job himself. (Of course, the paradigmatic case for a special counsel’s appointment, as we all understood during the drafting, is the presidentially nominated attorney general being asked to investigate the president.  But that understanding won’t stop a willful attorney general.)

"I believe the women," who accused Alabama Senate candidate Roy Moore of sexual misconduct, Senate Majority Leader Mitch McConnell (R-Ky.) said on Nov. 13. (The Washington Post)

These are the perverse stakes in the Moore case. This counterintuitive result may be why some, reportedly including White House officials, have been whispering about the possibility of trading Moore for Sessions. But for the strategy to succeed, it does require a confirmed attorney general (or at least a recess-appointed one). And that requires at least 50 votes in the Senate, something that might be hard to garner when there are only 52 Republican senators, several of whom have voiced public support for the Mueller investigation. One might think that senators such as Bob Corker (Tenn.) or Jeff Flake and John McCain (Ariz.) could extract a promise at a confirmation hearing for any nominee not to mess with Mueller or the regulations governing his work. But once confirmed, no attorney general would necessarily be bound by such a promise; he or she could point to any number of changed circumstances that required a different answer.

Our founders believed three things simultaneously: that elections would tend to produce statesmen; that no one was an angel; and that checks and balances were necessary to guard against abuse of power. Since seating Moore is unthinkable, maybe the best precaution would be for the Senate to commit before any hearings for a new attorney general to hiring Mueller as its own investigator if the Trump administration has him removed. Everything about Moore suggests he is not a statesman, let alone an angel. But in our zeal to protect government from this man, our other elected representatives must take care to ensure that our system of checks and balances does not suffer.

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