I am not saying I agree of disagree with the use of the law in this case but the problem that is associated with children having cameras at school could be fear of things like this: http://www.msnbc.msn.com/id/29017808/
Pardon, why does not having the camera at school help here? If they want to they can take the photos at home. In fact, I doubt many such photos would be taken at school even without a camera ban, why risk someone walking in on you?
I've had a lot of experience with schools banning a dependency of something rather than the thing itself, allegedly because they feel that gives them more time to prevent it. If they can take a camera away before students start sexting, then the student never will have started sexting. If they wait until the student starts, then it actually happened.
Of course, that means also banning all the legitimate uses of cameras, implying that the school thinks students' primary use of cameras is sexting, which I find obscenely offensive.