Impeachment is different, though. The oath challenges senators to think hard and critically about the difference between what is good for the party and what is good for the country. It suggests that there is a higher duty than winning the next election, something more important than pledging allegiance to one’s own biases. It requires politicians to do something they almost never have to do: be unselfish. Impartiality may be a nearly impossible standard, but there is something to be said for trying to live up to it.
McConnell probably won’t make that attempt. He will take the oath and then immediately violate it — even if, as law professor Lawrence Lessig has suggested, that violation makes him a perjurer. Who, after all, will hold him accountable?
The impeachment trial is meant to judge Trump. But the ramifications go beyond this presidency. History is already starting to render its verdict on the honor of McConnell — the impeachment trial is one more piece of evidence that will find him wanting.