Reb Eliezer,
Where did you get the idea that the era of Rishonim ended in 1400? The Abarbanel is widely viewed as a Rishon and he was born after 1400. The two dates I have seen as the cut-off for Rishonim is the expulsion from Spain in 1492 or the publishing of the Shulchan Aruch in the 1560s.
Klugeryid,
I mean no personal offense but you are writing about things of which you no very little. You are reading the phrase “High Crimes and Misdemeanors” the way someone would read it today, not the way it was understood at the time it was written. (l’havdil, it is like reading the Torah without the Oral Tradition). The writings from the Constitutional convention, the Federalist Papers, and the political nature of impeachment make clear that actual statutory crimes are not necessary. Alan Dershowitz’s argument that the behavior has to be “crime-like” (although he concedes it does not need to be a statutory crime) is plausible.
It should be noted, however, that at the time of ratification, common law crimes still existed. Common law crimes were crimes made up by Judges for actions that they felt should obviously be criminal (like murder or theft). So your scenario is not that far off the actual state of the law at the time the Constitution was written.