Those guys who did the September 11th thing would have been OK under those rules. The Canadian ones quoted sound a lot more sensible, leaving it open for interpretation, instead of having strict guidelines that could exclude relatively harmless things and allow in lethal ones. (Nothing is completely harmless which is why "zero tolerance" in this context isn't just silly, it's futile.)

The real way to deal with kids killing each other in school isn't this way. What's needed is to try and understand why it happens - issues like bullying and hyper-competitiveness, and disruptions in the community and in the family structure and so forth. Things like that just don't happen in most places and most times. It's not just random, like lightning striking in one place rather than another. More like cholera - there are reasons why it happens in some places and times and not elsewhere and else when; and if they can be identified they can be fixed.