Answer:
12 Angry Men is such a good movie! While I forget some of the details, I am going to have to go with that justice was served. Here are some of the reasons:
1. Because of Juror 8, the rest of the jurors were forced to view things logically and look at the facts of the case rather than making an immediate decision based on emotion. Remember, the rest of the jurors were willing to condemn the defendant for murder almost immediately, which points to the fact that they were all making illogical assumptions based on their emotion. This is especially seen in Juror 3, who was the last to vote 'not guilty.'
2. Juror 8 frequently put himself in the perspective of the defendant. This made him realize that the shock of seeing his dead father while being interviewed in the other room of the body would cause the defendant to be flustered, stutter his words, and remain incoherent/inconsistent. I believe it was Juror 10 who made a connection with one of the witnesses, who was an old man; Juror 10 argued that old men always want to appear helpful despite his old age, which could be the reason why the old man may have overemphasized or accidently lied in the process of trying to be helpful.
Justice is a very slow process, and 12 Angry Men shows that deliberations must be strictly logical and factual. Intense emotion when judging, in this case, the life or death of a young man, cannot be tolerated. This is especially seen in Juror 3, whose disproval of his estranged son was discovered to be the primary reason for his resentment of the defendant.