Tom, at this point of time, is a mockingbird, and the people who are killing him are determined to do so because that is how they feel their southern society should run; black people being 3/5ths of a person. Because of these traditions that have been going on for hundreds of years, Atticus is ultimately unable to convince the jury that Tom Robinson is innocent. In this quote, Atticus is explaining how you can kill blue jays because they only cause harm like actual criminals, but killing a mockingbird is like killing someone who is innocent. “Shoot all the Bluejays you want, if you can hit ‘em, but remember, it's a sin to kill a mockingbird.”(119). In this quote, Jem and Scout have just got their rifles, and Atticus is teaching them moral and physical rules. One of the moral rules he teaches prevents Jem from ever killing a mockingbird. This in turn relates to how Atticus informs the jury to do their job, but they do not follow through.
Foreshadowing over the course of the book like the turtle scene, and the discussion about whether it is a sin to kill a mockingbird, shows us that Tom Robinson is innocent. The jury coming to the verdict that Tom is guilty, was completely out of his race, not of what happened. Though there was foreshadowing to Tom's Innocence, there was also foreshadowing of him being charged as guilty. The title itself is telling us that the sinners or people of the jury are openly killing a “mockingbird” all because of the unjust segregation of blacks and