
Except it’s not a booby trap. Booby trapping your property is illegal on the basis that it could hurt someone who’s doing nothing wrong. The case that set the anti-trap precedent was one involving a rigged gun, set to go off if someone broke in the door. That’s obviously a risk to non-burglars who sometimes have to bust in doors, like firemen. There’s no legitimate reason to destroy someone’s mailbox that would make this an illegal booby trap.