You apparently are missing something, because the movie is exactly the opposite of that. Have you seen it?
The 12 angry men are members of a jury led by Henry Fonda, who turns out to be more of a defense attorney for the accused rather than a jurist, complete with inventing excuses and theories that were never even presented by the defense. At one point, they really go over the edge by claiming the one eyewitness, a woman, who claimed she saw the whole incident from her apartment window, had red marks on the side of her nose which HAD to indicate that she wears glasses, therefore she probably wasn't wearing her glasses because it was early in the morning and she was awakened from sleep, so therefore she really is not a reliable witness.
Then there was another scene where they actually tried to act out a dreamed up scenario, I think it was about how long it would take to get from one point to another, etc.
He even went so far as to blame society - oh, it was sickening.