Despite Tom Robinson's obvious innocence, he is convicted of rape as it is his word versus a white woman's. The social hierarchy must be maintained at all cost. If a "breach" in the system should allow a black man to contest the testimony of a white woman and win, then what might happen next?
Upon hearing the verdict, Jem goes out of the courtroom and cries. He has lost all faith in the citizens of Maycomb, in the sense of justice within the legal system, and in people in general. Jem's loss of innocence goes hand in hand with his increased understanding of just how powerful the pressure of social conformity can be.
Tom Robinson is a black accused of raping a white woman. In Maycomb, there is no way he will get a fair trial. Atticus knows this, but Jem still believes in justice. Throughout the entire trial, Jem believes that Tom will be found innocent.
Atticus does his job in proving there was no way that Tom was guilty. Jem is sitting in the balcony with the other black people, waiting for the jury to come back. Scout is there with him as well. When the jury comes back, the judge starts polling them. One after the other repeats "guilty". Jem is stunned. He slumps in his seat. He never thought Tom would be found guilty. He runs out of the courtroom and cries.
What is interesting about his reaction, is that, it is the culmination of everything Jem believed to be true, and he is now finding out they are not true. In a way, Jem has lost a very important innocence of his childhood. He will never again look at his town the same way. He won't ever think of his neighbor's in the same way either. Jem was so sure his father was going to win. Jem now has lost the gift of ignorance about social issues. Atticus wanted so badly to protect his children from the ugliness this trial was going to bring. In the end, however, he is unable to do this. Jem and Scout have forever been changed and shaped by these unfortunate events. Harper Lee had such a way of showing us how ugly people can truly be.
Tom is obviously innocent, but because of the harsh town and the racist prejudices they have put up, Tom was sentenced to prison. Atticus put an amazing case forth, yet because of the jury stuck in that mindset, Atticus could not save him. however, one person on the jury voted to save Tom and Atticus remarked that this is a great step forward. Jem was upset because even after all of this debate, Tom was wrongfully sentenced.
Jem is a very emotional person. Throughout the entire trial of Tom Robinson, he is sure that the jury will not convict Tom. But when the verdict comes back as guilty, he feels as though he is being physically attacked.
“Judge Taylor was polling the jury: ‘Guilty... guilty... guilty... guilty...’ I peeked at Jem: his hands were white from gripping the balcony rail, and his shoulders jerked as if each ‘guilty’ was a separate stab between them. (Chapter 21 pg. 349)