Yes, you do need to shoot center mass. The idea or though that you can shoot someone to wound them sounds great, but it is not feasible. In a high stress, high adrenaline situation, it is just not possible to shoot at the person's arm or leg and wound them. Along with the fact of how fast a person can move their arm or leg, officers are responsible for every round they fire. They are supposed to be aware of their target and what is beyond. The only way to be sure of that is to shoot at the biggest target possible, which is center mass.
As for emptying the magazine, officers are trained to shoot until the threat is stopped. That could be 1 shot or it could be multiple rounds. You'd be surprised at the number of people that can be shot multiple times and still continue to be a threat. I'm not sure what type of round was used by the officer in the Ferguson case, but many departments are going away from the 9mm as it is not effective in stopping someone.
With regards to the case in Amsterdam, power to them. If seven guys want to jump on a guy with a knife, they surely have guts. But, it is way to easy for that subject to easily harm those officers. As for shooting him, I don't know if that would be necessary, but this could have been a prime example of trying to use less-lethal tools like a Taser or beanbag rounds. In both of those cases, you still want someone there with the deadly force option as the subject can still perform serious bodily injury or death. That being said, sometimes you don't have the time to wait for the less-lethal options to arrive before action is needed as in the second St. Louis shooting of the knife-wielding subject.
- Merg