In 8-1 decision, court finds school violated First Amendment by punishing student for using a vulgar word in social media.

The Supreme Court extended its protection of student speech to social media on Wednesday, by an 8-1 ruling that a Pennsylvania school district overstepped its authority by punishing a high-school cheerleader who used a vulgar word on Snapchat when she didn’t make the varsity cheerleading team.

“America’s public schools are the nurseries of democracy,” Justice Breyer wrote, something that requires a free exchange of ideas that ultimately shape public policy. “Putting aside the vulgar language” Ms. Levy used, he wrote, “the listener would hear criticism, of the team, the team’s coaches, and the school—in a word or two, criticism of the rules of a community of which [she] forms a part.” Justice Clarence Thomas alone dissented. He argued that schools historically held expansive power over student expression, citing an 1859 decision by the Vermont Supreme Court against a student who called his teacher “old.” Such insubordination tended to “bring the master’s authority into contempt,” that court said. Likewise, Justice Thomas wrote, Ms. Levy’s Snap served to “subvert the [cheerleading coach’s] authority.”

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