Which is the social injustice for Zach Taylor?

As a black man living in the South, Zach Taylor has numerous disadvantages. This is a deeply racist society which, despite the passing of historic civil rights legislation, still treats African-Americans like second-class citizens. Despite his various challenges, however, Zach is blessed with a generally positive outlook on life. He's a very optimistic young man with hopes and dreams; he wants to become a lawyer one day even though he doesn't actually know any black lawyers in this neck of the woods.
Single-minded, hard-working, and fiercely driven, Zach has what it takes to make a success of his life, even with all the discrimination he encounters. Throughout the course of the book, Zach proves himself capable of overcoming adversity—such as when he's sent to prison—surmounting the many obstacles placed in his way by a society that doesn't believe he even has the right to dream of a better life.