Morse v Frederick
Joseph Frederick held a banner saying "Bong Hits 4 Jesus" referencing marijuana. Principal Deborah Morse took away the banner and suspended Frederick for 10 days and justified it by citing schools policy on drugs. Frederick sued believing it was allowed under 1st amendment. District courts agreed with Principal Morse and with her qualification of immunity, but when it went to the ninth circuit, they ruled that it was unconstitutional since Frederick was punished for the message rather then a disturbance and that Morse had no immunity qualification. The Supreme court, in a 5-4 decision, the court decided in favor of Morse.
This gave more power to the school and set the standard that schools have the authority to limit freedom of speech. This means that today and in the future that the school has the power, at least in certain cases, to limit freedom of speech.