Juror 6 comes into the bathroom and tells 8 that he thinks they should be done for the day already. "You're wasting your time. You ought to wrap it up," 6 says. 8 replies, "Supposing you're the one who was on trial."
8 goes back to the table and they discuss the downstairs-neighbor witness, an old man who said he heard what was happening upstairs because his window was open, and the woman across the street, who claims to have seen the stabbing. When 8 tries to make a claim about the issue, he notices men playing tic tac toe at the end of the table and goes and grabs their paper.
The men get more upset. "Has anybody any idea, how fast it takes an elevated train going at medium speed to pass a given point?" 8 asks the men. 5 guesses 10 to 12 seconds and 8 tells them that it does indeed take 10 seconds for a train to pass a given point, and asks the men if any of them have ever lived near the El tracks. "I just finished painting an apartment that overlooked an El line," 6 says, and 8 says that he once lived next to an elevated train, and that it is very loud. He suggests that the downstairs neighbor could not possibly have heard clearly if the train was passing by at the moment of the murder.
5 turns to 6 and expresses the fact that he doesn't believe the neighbor could have accurately heard. "Why would he lie, what's he got to gain?" 3 asks, when 9 chimes in: "Attention, maybe." When 3 snaps at 9, 6 scolds him for speaking so disrespectfully to an old man.
They ask 9 why he doesn't think the neighbor is telling the truth and he tells them, "The seam of his jacket was split, under the shoulder...I mean, to come to court like that. He was a very old man in a torn jacket and he walked very slowly to the stand. He was dragging his left leg and trying to hide it, because he was ashamed. I think I know this man better than anyone here. This is a quiet, frightened, insignificant old man who has been nothing all his life. Who has never had recognition or his name in the newspapers. Nobody knows him. Nobody quotes him. Nobody seeks his advice after 75 years. Gentlemen, that's a very sad thing to mean nothing."
Juror 10 is skeptical of this interpretation, and 9 shakes his head defeatedly. 2 goes to his coat to get a cough drop and offers them to the men, and 8 accepts one. 8 then brings up the fact that even if the neighbor heard the boy say he was going to kill his father, that is not the most unusual thing to say, and could have just been a heated exchange.
8 thinks that there is no way the boy would have yelled that, since he seems too bright, to which 9 replies, "He's a common ignorant slob. He don't even speak good English." In the middle of this, 5 tells the foreman that he'd like to change his vote to "not guilty."
7 stands up, frustrated, and argues that they shouldn't be reopening the case, since the boy already had a lawyer fight his case. 8 points out that the lawyer was court-appointed, which could mean that he wasn't very motivated to fight on the defendant's behalf. Suddenly, Juror 11 stands to read some notes he has written. He says that 8 has made some good points, and wonders why the boy would have come back home 3 hours after the murder if he had actually murdered his father. The other men suggest that the boy came back to get his knife, but 11 wonders why he wouldn't have just taken it in the first place.
Another juror suggests he panicked and ran away, but 11 wonders why—if he was panicked—he would have bothered to wipe away the fingerprints, but not take the knife. He elaborates, saying that the woman across the street testified that she screamed immediately after witnessing the murder, which the boy would have certainly heard. Based on this, 11 alleges, the boy isn't likely to have returned to the apartment, if he thinks he was seen.
Juror 9 get frustrated, reminding everyone that the downstairs neighbor saw the boy running out of the house at 12:10. "He says he did," 11 says, and 10 begins yelling in frustration. 8 interrupts him to call for another vote, and they all sit down yet again to vote on the verdict. Still, only the 3 jurors raise their hands for "not guilty," but then at the last minute, Juror 11 votes "not guilty" also.
"What is this? 'Love Your Underprivileged Brother' Week or something?" bellows 3, angrily. He demands that 11 stand and tell him why he changed his vote. "There is a reasonable doubt in my mind," 11 says.
7 asks what they are supposed to make of the downstairs neighbor, and 5 stands and tries to remember if the old man said he ran. 6 tells him that the downstairs neighbor did say he ran, and 8 asks to see a diagram of the neighbor's apartment. He is skeptical that the downstairs neighbor, who limps from a stroke the previous year, could have possibly gotten to his front door in 15 seconds.
They pull out the diagram of the apartment, and 8 suggests that the neighbor would have had to walk 12 feet to the door of his room and then 43 feet down the hallway in 15 seconds to see who was coming down the stairs. 8 wants to test how long it would have taken, and sets up chairs to measure how long it would have taken.
The film follows a rather straightforward premise and structure, that of one man standing up to the group and trying to use the law in the most thorough way possible, rather than take anything for granted. This structure is such that we consistently see 8 standing up to his fellow jurors, and them trying to intimidate or ignore him until he sees things his way. Thus, it is a fairly straightforward back-and-forth between two factions that vigorously disagree about how the role of the jury ought to unfold, resulting in the titular scenario, that of twelve angry men.
The precise dynamic between the jurors changes—though it remains quite angry—as they begin to listen to some of Juror 8's points. When he makes an argument for the fact that the downstairs neighbor cannot feasibly have identified the voice of the attacker while the elevated train was passing, he convinces some of the men. They, in turn, begin to come to the defense of the more vulnerable members of the jury, who are suffering abuse from the more bullish jurors. Juror 6 stands up for the elderly and kindhearted Juror 9, when Juror 3, the most aggressive of the bunch, speaks disrespectfully towards him, and a strange sort of society forms.
In this section, we are given a glimpse into the interior life of Juror 9, who agrees with Juror 3 that the old man could not have possibly heard clearly, and even provides a likely psychological portrait of the old man, who wants to have his voice heard in the trial. He believes that the old man is likely to have lied because he has felt insignificant for his whole life and wants to have a way of feeling like his voice is heard. The camera zooms in on 9, who is himself an older gentleman, as he explains the mental state of the aging—the fear of irrelevance. His words ring true because they seem heartfelt, and seem to narrate his own experience of his quest for relevance.
Every time the men talk about the case again, another detail comes to light that complicates their perceptions. In this way, they begin to see that the case is not nearly so straightforward as it had seemed. Slowly, 8 begins to get his fellow to jurors to look more closely at these details, which sows the seeds of doubt. They begin to question their own conclusions about what exactly happened, and think about the case more thoroughly, rather than simply taking the facts for granted and letting their initial prejudices get in the way.
The viewer is pulled in many different directions throughout the film. At many points, it seems as though 8 is just trying to belabor the deliberation process, as his fellow jurors suggest. He brings up details seemingly out of nowhere, does not have a strong argument for why the boy did not do it. 8 is bolstered only by his conviction that there is enough ambiguity in the case that they cannot be sure that the boy committed the murder. He follows his smallest suspicions and questions as a way of ensuring that they are giving the boy his due.