Bertram Cates is the defendant in the trial. He is loosely based on John Thomas Scopes of the famous Scopes Monkey Trial, though his characteristics are largely invented for the play. In Inherit the Wind, Bert is portrayed as a somewhat timid schoolteacher who, despite his firm belief in evolution, has trouble standing up for and explaining his beliefs in his extremely religious community. He is brave enough to want to continue the trial even when Rachel asks him to quit and simply admit that he is wrong, but he is scared of how his beliefs will be twisted during the trial. When he is given the opportunity to deliver a statement before he is sentenced, he overcomes his timidity to assert that the law as it stands is unjust. 

At the end of the play, despite being unsure of what his future will hold, he vows to keep fighting and take his case to the Supreme Court. His character serves to demonstrate The Value of Critical Thinking and the duty that people have to defend intellectual freedom. He and Rachel leave Hillsboro to make a life together, having come to a better understanding of their respective beliefs about evolution. Bert is satisfied that though Rachel does not agree with him about evolution, they are both able to think for themselves rather than blindly believing figures of authority.