How does the narrator portray injustice through the character of Attacus

Atticus Finch personifies the forces against injustice. He stands up for what is right even in the face of insurmountable odds. Atticus defends Tom Robinson because he needs a defence and it is the right thing to do, "if I didn’t I couldn’t hold up my head in town, I couldn’t represent this county in the legislature ... I could never ask you to mind me again."