John Thomas Scopes, a twenty-four-year-old football coach and general science teacher in Dayton, Tennessee, is the often forgotten figure in the 1925 Scopes “monkey trial,” dominated as it was by the expansive personalities of William Jennings Bryan, Clarence Darrow, and H. L. Mencken. Recruited by local businessmen interested in generating attention for Dayton, Scopes acknowledged using a text – one used by most science teachers in Tennessee – that taught human evolution in contradiction to the biblical account in Genesis, a violation of Tennessee's recently passed Butler Act. Scopes soon found himself in the middle of one of the most closely watched trials in U.S. history. Radio station WGN of Chicago broadcast the trial live each day, and all of the nation's major newspapers sent reporters to Dayton, with many printing verbatim transcripts of the trial. Syndicated columnist H. L. Mencken made daily reports that were published in scores of newspapers.

Scopes’ jury trial in Dayton and his appeal to the Tennessee Supreme Court were dominated by three different debates: one substantive, one procedural, and one concerning the autonomy of teachers in their classrooms. The substantive debate is one familiar to Americans today: How compelling is the scientific evidence for a very old earth, evolution in general, and the evolution of human beings in particular? In addition, if the evidence for evolution were strong, would this contradict the teachings of the Bible? These questions came to the fore when William Jennings Bryan took the stand for four hours and debated questions of biblical interpretation and human origins with defense attorney Clarence Darrow.