I think it is REALLY hard to overstate how dangerously naive a view of the american justice system that is
I don't understand what you mean. I would expect them to make the obviously correct decision, though I'm fully aware that they very often don't.
It depends on the definition of 'expect'. You should expect it of them, as in consider it unethical if they don't. You shouldn't expect them to live up to this standard, as in, if you were to bet on it, you'd likely lose.