The US Supreme Court's 1969 decision in Tinker v. Des Moines established that students can express personal opinions on controversial subjects unless it causes disruption. It involved students suspended for wearing black armbands to protest the Vietnam War. The 1988 case Hazelwood v. Kuhlmeier allowed more censorship of student publications that are school-sponsored. It distinguished between publications for educational purposes versus student expression forums. Courts have generally allowed censorship of obscene or libelous material in student publications, while vulgar language censorship depends on context.