The United States Supreme Court held that a student's right to free speech was not violated when a banner which he displayed at a school event was confiscated by his principal because she reasonably believed that it promoted illegal drug use.
Morse v. Frederick, 127 S. Ct. 2618 (2007).
First Amendment Does Not Require Schools to Tolerate Student Expression That Contributes to the Dangers of Illegal Drug Use: Morse v. Frederick,
Duq. L. Rev.
Available at: https://dsc.duq.edu/dlr/vol46/iss3/7