Atticus embodies Harper Lee's ideas of social justice, showing his respect for disadvantaged individuals throughout the events of To Kill a Mockingbird. Tom Robinson, the Cunninghams, Mayella Ewell, and Boo Radley are all citizens of Maycomb who must live within this society that often treats them unfairly, but Atticus tries his best to treat them well.

Atticus chooses to do the socially just thing by taking the case of Tom Robinson. When he speaks with Jem and Scout about the complexities of racism within their own community, Atticus is carefully to emphasize the importance of empathy and equality. He teaches his children to be curious about the experience of others, especially those who are different from them. Then Atticus takes his teaching one step further by modeling for Jem and Scout the behavior and attitudes he would like them to have. By taking Tom's case, Atticus acts on his own values of fairness and justice, showing the children that his words have true weight.

Atticus also models socially just behavior when he interacts with the Cunninghams. He treats them respectfully and works within their system of payment by accepting goods for his work instead of insisting on money. Similarly, Atticus shows respect to Mayella Ewell during the trial, addressing her with the formal and polite "Miss." These attempts at respect backfire, as Mayella feels patronized, but Atticus refrains from being disrespectful toward her; he continues to address her politely. Respect for all people is ingrained in Atticus; he cannot speak rudely even when the situation might require it.

Lastly, Atticus encourages Jem and Scout to give Boo Radley the space and privacy he clearly desires. This encouragement reflects Atticus's understanding that not all people can be treated the same way; in Boo's case, even friendly and well-meaning attention is unwanted. Atticus shows Jem and Scout that the socially just thing to do is to find out what an individual wants and to act on that knowledge, rather than assuming that everyone wants the same thing.

Social justice is the political and philosophical concept of fair and just relations between the individual and society. Ideas and institutions dedicated to promoting equal rights, distribution of wealth, and opportunities for all individuals are included under the umbrella term of social justice. Throughout the novel To Kill a Mockingbird, Atticus embodies the concept of social justice by defending Tom Robinson in front of a prejudiced jury. Atticus valiantly defends Tom, who is a marginalized, discriminated member of society, in a prejudiced court because he believes that Tom deserves fair and just treatment during his trial. Atticus believes that all citizens deserve a fair trial regardless of race, gender, or religion. Other instances where Atticus's actions and thoughts align with the ideas of social justice include allowing Walter Cunningham to pay him in food and supporting the fact that Bob Ewell collects welfare in order to feed his family. Atticus also supports public education by forcing his daughter to attend school and sympathizes with Walter Jr.'s difficult situation. Overall, Atticus is portrayed as an advocate for social justice by promoting equal rights and social programs that provide opportunities for all citizens. 

In To Kill a Mockingbird, author Harper Lee paints ideas of social justice by showing its antithesis--social injustice. Social injustice is particularly expressed through the theme of racism pertaining to Tom Robinson.

Even before the trial begins, Atticus knows it is unlikely he will be able to convince the jury to acquit Robinson. Atticus first reveals his feelings of hopelessness to Uncle Jack in Chapter 9 when he admits that all he really has is Robinson' word against the Ewells' words. Atticus further implies he knows Robinson will be tried unfairly due to racism because, as he phrases it, "[R]easonable people go stark raving mad when anything involving a Negro comes up."

Social injustice is also revealed when the characters discuss the verdict of the jury. In Chapter 21, Reverend Sykes informs the children that, no matter how much the evidence points to Bob Ewell as the guilty culprit, Reverend Sykes has never once seen a jury rule in favor of a black man over a white man. Plus, Jem points out that the jury did not have to sentence Robinson to death even after determining guilt; they could have sentenced him to 20 years in jail instead. Atticus further points out the injustice of the racial judicial system in the following:

Tom Robinson's a colored man, Jem. No jury in this part of the world's going to say, "We think you're guilty, but not very," on a charge like that. It was either a straight acquittal or nothing. (Ch. 23)

All of these revelations concerning the injustice of the Southern judicial system point to Lee's ideas that social justice can only be built upon ideas of mutual equality and mutual respect for fellow human beings.