People in Maycomb are biased against Tom Robinson simply because he is a black man. It is clear from the beginning of the trial that Tom has committed no offense, and that he has been wrongly accused of raping Mayella Ewell. In fact, it's obvious that Mayella's father was the man who beat her up, and that Tom (who has one stunted arm) is not physically capable of beating Mayella in the way she was...
People in Maycomb are biased against Tom Robinson simply because he is a black man. It is clear from the beginning of the trial that Tom has committed no offense, and that he has been wrongly accused of raping Mayella Ewell. In fact, it's obvious that Mayella's father was the man who beat her up, and that Tom (who has one stunted arm) is not physically capable of beating Mayella in the way she was attacked. Atticus says it best during his closing statement in Chapter 20 when he says "this case should never have come to trial. This case is as simple as black and white" (205).
The bias against Tom is mostly clearly shown when the all white jury finds Tom guilty despite this overwhelming evidence to the contrary. By choosing such an incomprehensible verdict, the jury shows that people in Maycomb believe that Tom is inherently guilty simply because he is black. There is no good reason for this prejudice, other than the fact that racism is a systemic tradition in Maycomb. In this way, Harper Lee illustrates the extreme senselessness behind racial prejudice.