"I never had any idea my bill would make a fuss. I just thought it would become a law and that everybody would abide by it and that we wouldn't hear any more of evolution in Tennessee." (John Washington Butler)

In the early 20th century, Darwin's theory of evolution was still a relative novelty, but it had spurred some Americans to react by preventing it from being taught in schools, including in Tennessee, which passed the Butler Act to prohibit teaching the theory in a state-funded school. This set the stage for proponents of the theory to challenge the law by having a teacher bring up Darwin's theory in a classroom, which is how a little known substitute teacher named John Scopes had his name attached to one of the most famous cases in American history.

While the case was technically challenging a law and proceeded like a normal trial, including an appeal to Tennessee's Supreme Court, the Scopes Monkey Trial was essentially a national debate on theology, science, and each one's place in the classroom. The trial is best known not necessarily for the results but for the rhetorical arguments that were made on each side and for the manner in which Darrow and Bryan squared off. In perhaps the most famous scene of the entire affair, Darrow actually cross-examined Bryan himself.