* Given that Supreme Court justices, like Presidents, tended in actuality to be men of independent wealth, was Hamilton’s fear that they might be reduced to poverty by a vengeful Congress justified? Was it more or less significant than the fear that removal from office might be a means for Congress to control Supreme Court decisions?
It could be justified. I’m sure there were historical examples, especially at the time when the judges served at the king’s pleasure. Over time, I think we’ve seen that the need to remove judges happens very infrequently. (Iowa not withstanding) Appointing the right judges to begin with seems to be more of a problem. Doing that is a judgment itself and best left to elected politicians, I think.
* Do improvements in medical science allow us to measure the decline in mental facility enough to be able to remove Supreme Court justices on that ground? Or is that prospect also unfeasibly subject to abuse?
Nope science does not. Not only can’t humans be always trusted to create a perfect test, a human can’t always be trusted to objectively interpret a perfect test.
I cannot think of any way to draft a perfect political test, as the honesty of the tester is a GREAT variable.