Prejudice, abuse, justice, or parental influence Essay?

I would recommend that you look at justice. The incidents you could refer to are Scout being 'punished' for being able to read by her new teacher in chapter 2. The ridicuous idea that Scout has been taught wrongly shows how the 'new' system of education does not allow for individual difference.

the treatment of Boo Radley as a young man after he is released into the custody of his father, and perhapd Heck Tate's judgement in chapter 30 of events leading up to Bob Ewell's death. Here he is clearly deciding that justice has already been served, although legally Boo Radley should be called to account.

The third point you could use would be the obvious fact that Tom Robinson is innocent of the charges against him, yet he is still found guilty in chapter 21 by the Maycomb court. Here you could look at how possible it was for justice to be served at this time.