You don't get any special rights in schools for your lockers, regardless of whether you pay a fee or not. You DO have a right to privacy, however, and in order to usurp that privalege or right, there has to be cause.
In this case I would think that cause was justified for them to search ALL of the lockers assuming that there was proper supervision.
Where I think that the students have cause here for complaint is the lack of parental notification after the fact even, and then you may also have the argument of duress for some that might have accompanied the threat... though most kids would have probably stuck it out just to see the fall out later.
A physical search of a kid, on the other hand, I believe has certain other criteria. We deal with kids a lot, and trust me, you cannot put your hands on them no matter what without absolute cause and searches of kids can go no further than the REQUEST to empty your pockets. Other wise you are dealing with the parents or you turn it over to the police.
Aloha...
