The second semester senior knew the rules. He and his parents most likely had to sign something that affect. In addition, this second semester senior had already been warned once.
It may be a stupid role and it may be legal. HOWEVER, it is against the rules of this school and the student knew that. Wearing sagging blue jeans and a tank top is also legal. However, if a student continues to violate the school dress code by dressing in sagging blue jeans and a tank top rather than the school’s required uniform, the school has the right to invoke disciplinary actions. If you don’t like the rules, go to a different school.