As the evidence is reviewed and discussed, many other weaknesses in the trial system are revealed and explored. What are these weaknesses? Why do they become so important in this case?

There are many weaknesses explored in the text. The first would be prejudice; this is exemplified in a number of different ways. For example: the defendant is from the slums (judged by his socio-economic background); one of the jurors (Juror #3) is having problems with his own son (this is reflected in his immediate belief the boy is guilty). Another weakness would be that the jurors are overly swayed by circumstantial evidence (the majority of the jurors take the word of the old man as gospel).

These weaknesses are so important because they're so difficult to overcome. What happens if you don't have Juror #8 questioning what could really be heard above the noise of the train? What happens if Jurors #5 and 6 don't realize they're actually not thinking logically about the answer to that question? Well, you'd obviously have an inaccurate verdict.