The ACLU’s predecessor was the American Civil Liberties Bureau, founded in opposition to the first world war and protecting under the rubric of free speech those who spoke out against it. At the conclusion of the war, the organization reformed into its now more familiar structure, focusing primarily on issues relating to the freedom of speech — which brought it into unexpected realms.

On this day, January 20, in 1920 the American Civil Liberties Bureau changed itself to “Union,” which marked its founding. It continued its work promoting anti-war speech, adding to it work for civil rights and a campaign against the Comstock Laws that outlawed obscene material distributed through the mail.

Despite vigorous work on all those fronts, the ACLU remained mostly unknown for five more years, until it took part in the Scopes trial in Dayton, Tennessee. Dayton passed a law making the teaching that humans were the product of evolution a misdemeanor, and the ACLU recruited a local teacher to voluntarily and knowingly break the rule so that they can defend him in the subsequent trial. The famous Scopes “Monkey” Trial ended in a conviction of the teacher (later overturned on a technicality), but brought the first real publicity to the group.