In Chapter 20, the scene involving Dolphus Raymond points to the motif of injustice and racial bias in the narrative of To Kill a Mockingbird.
When Dill is sickened by the treatment of Tom Robinson by the prosecuting attorney, Mr. Gilmer, he becomes sick to his stomach. So, Jem and Scout take Dill outside for some fresh air. Mr. Dolphus Raymond, a social outcast in Maycomb because he lives in the black section and has mixed children, calls out to Dill, "...I got something that'll settle your stomach." He offers his paper sack with straws in it that the citizens have often observed. Dill pulls at the straws and takes an ample sip. Mr. Raymond chuckles and Scout warns Dill to "watch out." But Dill tells an astounded Scout, "...it's nothing but Cocoa-Cola." Mr. Raymond laughs and tells the children to not "tell" on him as they have heard rumors of his drunkenness.
Further, he explains that he pretends to be an alcoholic because the citizens then have a reason that they can accept for his behavior; that is, they can rationalize, "He can't help himself, that's why he lives the way he does." This reason is one that the people of Maycomb can better understand than if he were to let them know that he has freely chosen to live in the black community. (After all, this is the Jim Crow South and Mr. Raymond is descended from upper-class people). Almost no one would really understand that he simply prefers to live with the African Americans, so the white people would try to force him to return to the their part of Maycomb and not "shame his people" [relatives].
Like Atticus, Mr. Raymond does not perceive African-Americans as "just Negroes." He feels that they are people with rights and freedoms, too. He tells Scout,
"You haven't even seen this town, but all you gotta do is step back inside the courthouse."
He implies that Scout, Jem, and Dill will witness the injustice that is committed against the African-American population. Certainly, Mr. Raymond feels that he knows what the outcome of the trial will be; therefore, he remains outside.