"Here's an idea: How about school officials get to know the kids, so that they can judge which kids are dangerous with what items, and learn to watch the at-risk or risky-to-other kids more closely, instead of trying to stick to a program that requires zero intelligence to administer?"
O.K., this is just a response to the above quote and certainly not an ad hominem attack. Having done a fairly decent job of raising four children and thereby having dealt with school administrators and school teachers over a span of many years, my observation is that the kind of people who become school administrators and school teachers aren't the kind of people who like to make decisions...particularly decisions with serious consequences.
It's a pity, but my previous post in this thread really does say it all: "Those who can, do; those who can't, teach."
There is, of course, the Elephant in the Room, about which we don't dare talk, and which subject is not p.c. and is, in fact, practically taboo. Were it not for that Elephant in the Room, rules concerning bringing weapons to school wouldn't be necessary.