People are convicted on metadata. If not that, than motive. If neither of those are present, physical evidence is nearly meaningless. 

The legal process is meant to prevent not simply criminal corruption, but simpler forms, such as padding crime stats, or innate bias, both of which can be manipulated. To some degree, the founding fathers were aware of them, and so are judges. The entire legal system is crafted based upon multiple perspectives of how society functions, although it is quickly changing to one where the legal system is that of a perspective of he who receives orders.

I posited a question once to someone, "What if you were the Nazi?"

All I got was, "I don't understand."

"Where does responsibility end, the person who sets the policy, the person who writes the policy, the person who interprets the policy, the person who gives orders, the person who carries it out?"

*silence*

All I could prove is I have potential and it is being stymied in some way.

How does one prove a counterfactual to people who just aren't hearing it?

Or to put it another way, how can millions of card carrying party members ever be wrong?