Justice and injustice in To Kill a Mockingbird?

Atticus Finch is the symbol of justice. He is literally an anti-racist. He's a lawyer who defends Tom Robinson, a black man, in a time of great racism. He is a huge hero.

Racism is injustice. Bob Ewell is the main antagonist. He accuses Robinson of something that he knows Robinson did not do; therefore, he is just lying. He later tries to kill Atticus' kids, Jem and Scout, but does not succeed in doing so, even though Jem gets a broken arm.