Never bring a knife to a gunfight!
First of all, remember that if somebody pulls a knife on you and they're standing 21 feet or closer to your body and you DON'T aready have a gun in your hand, if you attempt to draw, you will likely die. That's the oft mentioned 21 foot rule. It means that within 21 feet an attacker can reach you and stab at least twice in 1.5 seconds.
Originally Posted by Dingle1911
Can you draw that fast and be accurate? "EYEBALL" accurate? Every time? Even police officers who already have their guns in hand often have to retreat and fire AND move out of the way as the attacker advances with his knife.
Regarding "If one shot is justified, are more..."
As a retired prosecutor, I'd say that in the courtroom what they'll be looking at is whether you stopped shooting when the threat evaporated. The right to use deadly force ends when the threat ends.