Clarence Darrow was a famous American civil rights attorney of the 19th and 20th century. His most famous case with the "Scopes Monkey Trial", but he was involved in other high profile trials. This case was for a black family that moved into a white neighborhood and were attacked by a white mob. Henry Sweet of the family fired back in self-defense, killing a member of the mob. Partially on Darrow's closing arguments, Henry Sweet was acquitted under self-defense. Charges against the rest of the family were also dropped.
Darrow's speech is well ahead of its time, especially for a white man. He doesn't shy away from things like asking the all white jury to consider its own prejudice. In the hundred years since this speech, many Americans still are resistant to confronting their own prejudices.