“What did the Framers think about impeachment?” This question is everywhere these days, and the answer that follows often references James Madison’s rejection, on September 8, 1787, of the term maladministration in favor of “high crimes and misdemeanors.” The implication is, supposedly, that a president cannot be impeached for mere poor governance. It’s a good story, and one that can be found in accounts as far back as Watergate.

The source of this story is Madison’s notes, his record of the Constitutional Convention, which is today stored in a vault at the Library of Congress. But there’s just one problem: The specific sheet that is the only evidence of the famous impeachment conversation isn’t a solid source. I spent years studying Madison’s manuscript, and this sheet is the oddest one in it. It does not date from 1787, but from the early 1790s. Maybe the conversation happened in 1787 on the floor of the convention, as Madison tells it. Maybe it didn’t. But either way, the uncertainty is itself instructive, a reminder of our distance from the framing generation; historical evidence cannot absolve Americans now of their obligation to interpret the Constitution for today.