Which case established that the government could not interfere with symbolic speech in schools?

The case that established that the government could not interfere with symbolic speech in schools is Tinker v. Des Moines. This landmark Supreme Court decision, decided in 1969, concluded that students do not "shed their constitutional rights to freedom of speech or expression at the schoolhouse gate." The case involved students wearing black armbands to protest the Vietnam War, and the Court ruled that this form of symbolic speech was protected by the First Amendment, provided it did not disrupt the educational process.

This decision underscored the importance of preserving free expression in educational settings, affirming that students have the right to engage in non-disruptive symbolic speech. It set a significant precedent that limits the extent to which schools can regulate student expression based on its content, ensuring a balance between school authority and students' rights.