In 12 Angry Men, the jury is deciding the fate of a young man who is being prosecuted for stabbing his father to death. The case is pretty much a slam dunk. There are two eyewitnesses to the murder, the father has been stabbed with the exact kind of knife the son bought a day before, they had just had a fight, and the young man claimed that after the fight he went to see a double feature at the theater, neither movie which he could remember and no one saw him there. He claimed the knife fell through a hole in his pocket on the way to the theater. According to one of the jurors, the case was not fought well by the young man's attorney and so he took it upon himself to change the mind of the other eleven jurors that voted for guilt.
The entirety of the movie is spent with Fonda acting more like Jose Baez than a fellow juror manipulating the others to think more about the case, offering alternative theories to what might have happened like the woman who saw the boy stab his father may not have had her glasses on (but it was not determined if she really needed glasses or what her vision without them would have been), the man who heard the young man say "I'll kill you!" might have been making it up as a train going by at that time might have drowned out anything anyone said ("might" because they never had proof that depending on the walls of the building and how sound carried, he might have been able to hear voices just fine). The boy might have forgotten the films in the trauma of finding out about his father's murder.....and so on. While these are certainly interesting points to bring up and explore, what happened in the movie was each juror changed his verdict just because one piece of evidence was made a bit murky. Emotions ran wild during the discussion and the quick turnarounds showed how little the totality of the evidence was being considered. Just a few hours after entering the jury room to deliberate, eleven men changed their minds and voted "not guilty" along with Fonda, likely letting a killer back out into society.
Now, we have the Bill Cosby brouhaha. Today there is information that he admitted during a civil case to giving quaaludes in the 70s to women he might like to have sex with. Many have gone nuts with this claiming this proves that Cosby is a rapist just like those women said he was. But, they ignore that in the actual civil case, he does not admit to giving women quaaludes without their knowledge and the woman it is said the case is about admits to accepting the drugs willingly.
To date, there is NO proof that Bill Cosby raped anyone. There is pretty good proof he is not so moral and a sleaze as are a number of men in Hollywood - I know because I had been offered candy dishes with a variety of drugs in them and I refused to swallow any. I also refused to sleep with producers or actors to get work, but I know quite a number of women (and men) who did. I saw them take drugs and I saw them cuddle up to men they thought could give them a break in the acting world and I saw them go with them into the back room.
I am not saying that Cosby didn't rape any women and I am not saying these women are lying and I am not saying no woman has ever been given drugs without her knowledge and woken up to find a man raping her. I am simply saying, that if we are going to decide if someone is guilty or innocent, we ought to base our determinations on evidence, not emotions.
This is why the jury system fails. Untrained people often do not understand the evidence or even what evidence is, they often do not understand what the totality of evidence means (and it means that when you put all the evidence together there is not reasonable doubt that the person is guilty; it does not mean that you pick out one piece of evidence, find one very improbable but possible theory to explain it differently and ignore all the other evidence), and they often allow emotions and subjectivity to color their conclusions.