Under the Senate’s current rules, senators would start an impeachment trial by taking an oath pledging to do “impartial justice.” But Senate majority leader Mitch McConnell has already said he won’t be an “impartial juror,” and senators in both parties have tipped their hands about their likely votes in ways that we would never tolerate from jurors in advance of regular trials. The senators are also not selected using the mechanisms we use to try to find impartial jurors.
So should the oath be junked? The Constitution requires that there be one. And it’s a good thing to remind the senators that they have a duty to do right by the Constitution, not just by their party.
Either the oath should be changed, then, or “impartial justice” needs to be interpreted in a very different way from usual given the highly political context of an impeachment trial. This is another way in which thinking about impeachment by analogy to criminal law clouds rather than clarifies the constitutional stakes.
Update: I fixed a mistake–the oath talks about “impartial justice,” not “impartial jurors” as I originally misquoted it–brought to my attention by a tweeter.