Since the novel is written from Steve's point of view, the question really is if Steve thinks he received a fair trial. At one point, he recalls a dream that seems to sum up his feelings.
The dream took place in the courtroom. I was trying to ask questions and nobody could hear me. I was shouting and shouting but everyone went about their business as if I wasn't there.
Steve and his lawyer know that, because of his race, he will have to work even harder for the court listen to his point of view. As his lawyer, Miss O'Brien, states:
“My job is to make sure the law works for you as well as against you, and to make you a human being in the eyes of the jury.”
The reader has to presume they do listen, and, therefore, he does receive a fair trial, because they find him not guilty. There is, however, a sense that he is actually quite lucky to get away. After the trial his father rejects him:
My [Steve's] father is no longer sure of who I am. He doesn't understand me even knowing people like King or Bobo or Osvaldo. He wonders what else he doesn't know."
His lawyer also finds it difficult to look into his eyes.
When Miss O'Brien looked at me... what did she see that caused her to turn away? What did she see?