From July 10 to July 21, 1925, Bryan participated in the highly publicized Scopes Trial, which tested the Butler Act, a Tennessee law barring the teaching of evolution in public schools.
The defendant, John T. Scopes, had violated the Butler Act while serving as a substitute biology teacher in Dayton, Tennessee.
His defense was funded by the American Civil Liberties Union and led in court by famed lawyer Clarence Darrow.
No one disputed that Scopes had violated the Butler Act, but Darrow argued that the statute violated the Establishment Clause of the First Amendment.
Bryan defended the right of parents to choose what schools teach, argued that Darwinism was merely a "hypothesis," and claimed that Darrow and other intellectuals were trying to invalidate "every moral standard that the Bible gives us."
The defense called Bryan as a witness and asked him about his belief in the literal word of the Bible, though the judge later expunged Bryan's testimony.

Ultimately, the judge instructed the jury to render a verdict of guilty, and Scopes was fined $100 for violating the Butler Act.
The national media reported the trial in great detail, with H. L. Mencken ridiculing Bryan as a symbol of Southern ignorance and anti-intellectualism.
Even many Southern newspapers criticized Bryan's performance in the trial; the Memphis Commercial Appeal reported that "Darrow succeeded in showing that Bryan knows little about the science of the world."
Bryan had not been allowed to deliver a final argument at trial, but he arranged for the publication of the speech he had intended to give.
In that publication, Bryan wrote that "science is a magnificent material force, but it is not a teacher of morals."
From July 10 to July 21, 1925, Bryan participated in the highly publicized Scopes Trial, which tested the Butler Act, a Tennessee law barring the teaching of evolution in public schools. The defendant, John T. Scopes, had violated the Butler Act while serving as a substitute biology teacher in Dayton, Tennessee. His defense was funded by the American Civil Liberties Union and led in court by famed lawyer Clarence Darrow. No one disputed that Scopes had violated the Butler Act, but Darrow argued that the statute violated the Establishment Clause of the First Amendment. Bryan defended the right of parents to choose what schools teach, argued that Darwinism was merely a "hypothesis," and claimed that Darrow and other intellectuals were trying to invalidate "every moral standard that the Bible gives us." The defense called Bryan as a witness and asked him about his belief in the literal word of the Bible, though the judge later expunged Bryan's testimony.
Ultimately, the judge instructed the jury to render a verdict of guilty, and Scopes was fined $100 for violating the Butler Act. The national media reported the trial in great detail, with H. L. Mencken ridiculing Bryan as a symbol of Southern ignorance and anti-intellectualism. Even many Southern newspapers criticized Bryan's performance in the trial; the Memphis Commercial Appeal reported that "Darrow succeeded in showing that Bryan knows little about the science of the world." Bryan had not been allowed to deliver a final argument at trial, but he arranged for the publication of the speech he had intended to give. In that publication, Bryan wrote that "science is a magnificent material force, but it is not a teacher of morals."
William Jennings Bryan