[AHerald]

Government school policy is still government policy.

So because a public school operates under governmental authority that makes an individual public school's, or school district's, dress code policy equivalent to government policy? ... Perhaps a legal expert here can explain.

[thoughtomator]

Yes. Any institution run by the government is bound by the same rules the government is bound by. Otherwise, the government could evade any restriction upon it simply by delegating a power to an institution specifically created to abuse it!

Anyway... government schools are bound by the First Amendment. No law against the exercise of free speech is valid - they cannot use the content of the message to determine whether or not it can be displayed/worn.

A private school could do the same thing this public school did, and it would be legal. A public school cannot.