I liked the following quote, from a federal court opinion in Massie v. Henry:
With respect to hair, this is no more than a harkening back to the fashion of earlier years. For example, many of the founding fathers, as well as General Grant and General Lee, wore their hair (either real or false) in a style comparable to that adopted by plaintiffs. Although there exists no depiction of Jesus Christ, either reputedly or historically accurate, He has always been shown with hair at least the length of that of plaintiffs. If the validity and enforcement of the regulation in issue is sustained, it follows that none of these persons would have been permitted to attend Tuscola Senior High School.What brought me to it was the story of a 12-year-old student who received detention because of his hair color. He was rewarded for his good grades at home by being allowed to dye his hair in his school's colors - a nice shade of blue. School officials took offense. (It also made me wonder how many school administrators out there might touch up a dash of gray with a little something out of a bottle.) A section from the Massie opinion I liked even more was this one:
So, too, we turn to the sufficiency of proof of state interest and violation of the rights of others in this case which may constitute justification for the regulation. There was no evidence that consideration of health entered into the picture; the only claimed justifications were the need for discipline and considerations of safety. We think the proof of the disruptive effect of some students having long hair was insufficient to justify the regulation and its enforcement. Proof that jest, disgust and amusement were evoked, rendering restoration and preservation of order difficult, and that there were threats of violence was insufficient. Moreover, there was no proof of the ineffectiveness of discipline of disrupters or a showing of any concerted effort to convey the salutary teaching that there is little merit in conformity for the sake of conformity and that one may exercise a personal right in the manner that he chooses so long as he does not run afoul of considerations of safety, cleanliness and decency. In short, we are inclined to think that faculty leadership in promoting and enforcing an attitude of tolerance rather than one of suppression or derision would obviate the relatively minor disruptions which have occurred.The other case referred to, but not named, in the article about the blue-haired pupil wasn't about hair, but rather about three children who wore black armbands to school to protest the war in Vietnam. That case is Tinker v. Des Moines Independent, and a line that frequently is quoted from the opinion in that one is that students do not, "shed their constitutional rights to freedom of speech or expression at the schoolhouse gate."