> I agree that this policy is a good one, but I don't think should be enforced by the school. I'm not an educator, but if I were I don't think I'd be happy about forfeiting my policy control to a government official.

Educators in public schools are government officials.

> How would a law like this even be enforced?

Laws and policies prohibiting objects in schools are common, and typically enforced through confiscation when the offending item is observed; whether after that the item is forefeited, returned to parents, or has some other disposition , and whether there is subsequently legal proceeding or additional penalty, varies considerably but is generally peripheral to primary enforcement.