pnichols:
That bear spray is a wonderful idea until the threat is upwind of you in a fair breeze then you shoot yourself in the foot so to speak.
WTP:
It is generally considered that, in optimal conditions, 7 yards or 21 feet is the point at which you have recognized an imminent threat and moved from the alert state to the active state - meaning you are reacting to an identified threat rather then aware of it's existence. 21 feet is the distance a man can cover in the time it takes to draw an unconcealed pistol.
It is generally accepted that most SD shootings take place at 5-7 feet indicating that the 21 foot rule is somewhat accurate. Unfortunately, even without stress, there are people that will miss at that range. Here in Michigan one is expected to put 30 rounds on paper at 12 feet in order to qualify for a Concealed Pistol License. A lady on my course had to leave the range to purchase an additional 50 round box of ammunition in order to qualify. Personally, I would have sent her home and told her to come back when she can hit 30 of 30... But I'm an awful person... ;-)