Who's fault do they think that is?
Zero tolerance came out of schools and principals protecting themselves from lawsuits over discretionary decisions that parents and others felt were wrong and hurt their children. Parents who refuse to take responsiblity for their children dump them on the schools, and then the parents sue the schools when they blame them for their children's behavior.
The schools' response was to take decisions away from the principals (and therefore the litigations) by enacting zero-tolerance policies that spelled out exactly what was to happen under any circumstance. Since the schools can't foresee everything that could happen, they simply broaden the definition of things to include absolutely anything.
That's why kids are being expelled these days for pointing fingers and going "bang."
-PJ