Pretty thorough job of developing the contract, although some of the language in places is conflicting. It clearly states slacks for males, and also that any anticipated dress that might violate the rules needs to be cleared in advance by Dr Caroll or Mr Biggs. Seems like that is the place to go with all your supporting documents, and request a specifically written ruling or exception be provided to you and signed by the appropriate deciding authorities on official school or board letterhead---this will be helpful the night of prom if he is allowed to go and there is some other chaperone at the door who might not be aware of his special ruling, as well as usefull if you have to go the legal or media route.

You might want to start to be prepared for disappointment---places who have done this much preparation with a contract for the event have generally done their background work to support their positions, and tend to not be flexible, as flexibility for one opens the door to others to test the limits of that flexibility. I still believe your son should be able to go to the event kilted, just playing devil's advocate should the wall go up fast, high, and thick against you. If not allowed to go to the prom kilted send him in p@nts, then on another night you could always plan some sort of similar but smaller formal gathering of his friends on your own terms---a kilt coming out party of sorts--for graduation or some other celebratory event where he can come kilted, and hey, maybe even his friends could rent kilts for the night. Rent a room at a local restaurant for a nice dinner and DJ'd dancing under parental chaperoning with similar restrictions to the contract for prom. Someone's big back yard with catered hors d'ourves and an outdoor dance floor, or dancing on the driveway. Just a fall back thought should things not go your /his way.

Another thought to further the kilt support might be to have his date/dates wear matching tartan sashes or even tartan dresses as part of their ensemble---shame to let the girls wear tartan but not your son.

Either way we are in your corner in any way we can help. It is a good thing that you are starting now and have lots of time to work through the process and be settled with the outcome either way, well before the event itself.