in chapter 9: Although Atticus told Scout that he was 'simply defending a negro', what was the evidence that this was not a simple case at all?

Scout feels the pressure of the town. She sees that the white people in Maycomb have already decided that Tom is guilty and that her father defending Tom is a betrayal of the white people. A boy at school, Cecil Jacobs, teases Scout, saying that her father "defends niggers".