I'm going to challenge you here. (shocker). Years at the coal face of social work has taught me that children absolutely do try and stab people.... in London, that often means each other - but they do also often attempt to stab other people too.

In the instance of describing her as a child this is absolutely correct. US citizens are not adults until they are 18 in most States. Whatever else you may believe about the matter - shooting a child is rarely the best outcome any reasonable person would advocate for. I see the distinction you're trying to make between 'children' and 'proto-adults' as teenagers often are - but such a distinction isn't legally sound - nor does it take into account the complexity of being teenagers - who have far more in common with toddlers than with adults in terms of emotional regulation.

Teenagers are irrational, unpredictable and prone to lapses in judgment because of their brain chemistry. If any adult, let alone a police officer, can't improvise a better solution than shooting them during an amygdala hijack - then US society needs to be more introspective. Such introspection includes how police officers are trained and when 'reasonable force' is needed.