Tinker V. Des Moines Independent Community School District (1969)

Facts:
Des Moines school district students, John Tinker, his sister Mary Beth Tinker and Christopher Echardt, decided along with their parents to protest the Vietnam War by wearing black armbands to school during the Christmas holiday season. The principal of Des Moines School District, upon learning of their intentions, warned all students wearing armbands to remove them or be suspended from school. Regardless of the principal's request, the Tinker siblings and Christopher wore their armbands to school, and they were asked to remove them. When they refused, they were suspended until after New Year's Day.
Decision:
When the petitioners were wearing armbands at school they remained quiet and passive. They were not disruptive, and did not impinge upon the rights of others. In these circumstances, their conduct was within the protection of the Free Speech Clause of the First Amendment and the Due Process Clause of the Fourteenth. Further, First Amendment rights are available to teachers and students, subject to application in light of the special characteristics of the school environment. In addition, a prohibition against expression of opinion, without any evidence that the rule is necessary to avoid substantial interference with school discipline or the rights of others, is not permissible under the First and Fourteenth Amendments.
Conclusion:
In this case, the wearing of armbands was "closely akin to 'pure speech'" and protected by the First Amendment. In the school environment, it is implied that there are limitations to free speech, but in this case the principal lacked reasoning for imposing the limitation. The principal had failed to show that the conduct of the students would substantially interfere with appropriate school discipline.
Source: http://www.associatedcontent.com/article/2499583/case_brief_tinker_v_des_moines_independent.html?cat=17