U.S. public schools can restrict student speech if the speech could cause a "substantial disruption," is lewd, is school-sponsored or involves illegal drug use.
| Tinker v. Des Moines | 1969 | May restrict student speech if there is a reasonable expectation that it will cause a substantial disruption of, or material interference with, school activities, or that it will impinge on rights of others. |
| Bethel v. Fraser | 1986 | May restrict lewd, indecent, vulgar or plainly offensive speech, even if there is no disruption or impingement of others. |
| Hazelwood v. Kuhlmeier | 1988 | May restrict school-sponsored speech if the restriction is reasonably related to legitimate educational concerns. |
| Morse v. Frederick | 2007 | May restrict speech that a reasonable person could interpret as promoting illegal drug use. Deference given to school administrators on whether the speech at issue promotes such activity. |
