As noted by How Stuff Works, the 1950s in America included a wild, paranoid time known as the Red Scare when people were so worried about communist infiltration they were perfectly happy to ruin people’s lives over any appearance of disloyalty. Led by bullying, populist Senator Joe McCarthy, the persecution of people for political beliefs or membership in supposedly subversive groups was known as McCarthyism. In New York State, for example, a law was passed that allowed schools to fire teachers if they joined “subversive organizations.”
According to History, a group of teachers and parents challenged the law. The teachers were all fired, and the group took it all the way to the Supreme Court, which ruled 6-3 in favor of the law on the reasoning that it was well within a state’s rights to protect “immature” minds from “subversive propaganda.” Notably, the teacher’s union, which had encouraged its members to resist the law, vowed to keep fighting to overturn it.
In 1954, Senator McCarthy was censured by the Senate and McCarthyism faded away. A few years later, a professor, Harry Keyishian, refused to cooperate with the law, was fired, and he sued. This time, the Supreme Court ruled 5-4 against the law, describing it as overly vague and infringing on Keyishian’s First Amendment rights, thus overruling the Adler decision.