The trial of Tom Robinson and the guilty verdict that he receives serves as another example of the loss of innocence that Jem and Scout suffer during the chapters of To Kill a Mockingbird. Before the trial begins, Scout has to deal with schoolmates and her cousin, Francis, who refer to Atticus as a "nigger-lover" for his defense of Tom. The children hear gossip about their father on the streets of Maycomb, and they see the support that Tom receives from the black community when they visit his church with Calpurnia. They see first-hand the anger and potential evil of the community when they come to Atticus' rescue from the lynch mob at the jail just before the trial begins.
Sneaking away to attend the trial in person, Scout and Jem witness the evidence presented and decide for themselves that Atticus has made a strong case for Tom's innocence. Yet the jury cannot overlook the fact that Tom is black and that Mayella is white, and they vote to convict him. Scout sees that the jury consisted of
... twelve good men and true... Then Mr. Underwood's meaning became clear. Atticus had used every tool available to free men to save Tom Robinson, but in the secret courts of men's hearts Atticus had no case. Tom was a dead man the minute Mayella Ewell opened her mouth and screamed.
The decision made Jem question the need for juries, and Miss Maudie had to respond to his "fatalistic noises," telling him that there were people in town who supported Atticus and how important he was to the community. Jem and Scout both feared for Atticus' safety after the threats made by Bob Ewell, and it made Jem recognize that there were distinctly different types of people living in Maycomb. Tom's death even made Jem more aware of the value of all living things, evidenced when he chastizes Scout after finding her about to "mash" a doodlebug. The outcome of the trial made both of the children grow up a little more quickly, once exposed to the real world where life isn't always fair and just.