Zero Tolerance has to do with bringing weapons and drugs, and sexual harassment. Sometimes, threats and intimidation are listed as Zero Tolerance "offenses".
I worked 7 years in my neighborhood middle school and rarely saw a kid expelled under Zero Tolerance. Kids brought knoves to school, but the system is already so backlogged, they only expel the most serious situations.
And while some of you see it as "the man" trying to keep you down, I see it as trying to make schools safer for children. If you had any kids, you might see it that way, too.
Dumb enough to bring a knife on campus? You deserve some kind of consequence, dumbass. Hide that shit in the bushes and do your thang in the street, off-campus.