A more thorough explanation:

Tinker v. Des Moines Independent Community School Systems (1969) was a Supreme Court case that established the protection of first amendment rights for students in publicly funded schools. The case involved five students who were expelled for wearing black armbands to school as a symbol of their opposition to the Vietnam War. The school district defended its policy against the wearing of the bracelets, fearing that it would lead to violence. The students were not allowed back to school until they removed the bracelets, and their parents sued the school district.

The district court and appellate court both ruled in favor of the school district, citing the need for schools to prevent disruptive conduct. However, the Supreme Court overruled the lower courts, stating that a student's first amendment right to freedom of expression must prevail over the needs of the school, unless there is a legitimate reason to expect disruptive conduct. The Court emphasized that freedom of expression most strongly protects minority views on political matters.

Tinker v. Des Moines became a landmark case that has evolved since the ruling. Cases addressing later school free speech issues have tested the limits of the Supreme Court's opinion in Tinker. Some cases appear to limit the protections in Tinker, while others uphold these protections. Many of the boundaries remain unclear between free speech rights of the student and the rights of administrators to manage school conduct.

• In Morse v. Frederick, the court allowed the expulsion of a student for displaying a sign stating "Bong Hits 4 Jesus" across the street from the school.
• In Mahanoy Area School District v. B.L., the court upheld the protection of a student's right to free speech when she posted a profanity-laced message on Snapchat outside of school hours.

These examples illustrate the evolving nature of free speech rights in schools. While the Supreme Court has established protections for students' first amendment rights, the boundaries of these protections are still being tested in court cases.