Spot on comments above about the indecision period. So, you see some goof -ball charging at you from at or within the specified distance; are you going to be able to make the correct decision and draw and shoot to stop the threat in time to avoid that knife being used to dump your intestines on the floor or not? Think about it, not everyone headed your way in a hurry is out to do you bodily harm.
In today's litigious society with the armor of qualified immunity and under color of law being stripped away and with the over jealous politically influenced district attorneys charging police right and left for any misstep; I can see the indecision time period increasing with misplaced hesitation. Hesitation being the operative word injecting itself into a kill or be killed choice.
Everything depends on the prosecutor in the county/city that shoot happens unfortunately. The law is written, but the prosecutors proceed with their interpretations sometimes politically which isn't the way law is supposed to be administered.
We see this all the time unfortunately in courts.
