Just because you say so doesn't make it true. Not all crimes with weapons are premeditated a day in advance. If someone brings a knife to school every day, th

Just because you say so doesn't make it true. Not all crimes with weapons are premeditated a day in advance. If someone brings a knife to school every day, they'll almost definitely have that knife available when a fight arises, whereas if they don't habitually bring a knife, they may not. Also, I suspect that such zero-tolerance policies are popular among the majority of parents, to whom the other kid is generally the frightening one, and whose own wouldn't hurt a fly.