Robert Delahunty and John Yoo are in good company in thinking that the Constitution forbids the Senate from convicting a former official in an impeachment trial. But I think their argument for that view has two great weaknesses.

The first is that they wrongly take the other side of the debate to “concede. . . on the constitutional text” — by which they seem to mean that we acknowledge that the text of the Constitution confines impeachment to currently serving officials. That premise makes their argumentative work easier: To refute the other side as they present that side, they need establish …