What should be the standard of proof in a Senate impeachment trial?

This goes with what we were discussing a couple weeks ago, in that removing an elected President is disenfranchising the states. So if we are to weigh potential outcomes here, there are four:
[ul][li]Impeach and convict a guilty president, and justly disenfranchise the states[/li][li]Impeach and convict an innocent president, and unjustly disenfranchise the states[/li][li]Acquit or fail to press charges against a guilty president, abandoning justice[/li][li]Acquit or fail to press charges against an innocent president, which is just[/ul][/li]If we strike out the positive outcomes to look at the worst case scenarios, one the one hand we disenfranchise the states, and on the other we let a criminal run the government. A standard of proof has to strike some sort of balance between these two undesirable ends of a spectrum, and the question is how much we prefer one outcome over the other.

It is my opinion that I would rather have a criminal run the government than (unjustly) disenfranchise the states, most if not all of the time. Just because the President is criminal doesn’t mean our nation ceases to function. There are checks and balances, which I trust, including impeachment for more overt acts or patterns that may arise in the future. But disenfranchising the states is like a penultimate evil; second only to disenfranchisement of the people or perhaps mass murders.

Consider this: a conviction for treason requires a very, very high bar. The framers could have written in an exception, to say that treason has a lower bar for impeachment. They didn’t do that. You need two witnesses to an overt act of treason, there can’t be any doubt as to the treasonous nature of the act. Something like assembling a force of men with the intention of overthrowing the government, or actually joining the ranks of an enemy on an actual battlefield, or knowingly providing material aid such as a car and travel documents to an known spy. If a President does all of that, but you don’t find two witnesses, you can’t impeach him for treason. If there is a credible accusation that the President literally joined the Nazis in the fields of Europe, but you don’t find two witnesses, you can’t impeach him for treason. Let that sink in. That’s the burden of proof.

~Max