If a round severed his spinal cord that would have also caused him to slump over like that. I don't know if the headshot took him down because he did seem to flinch when he was still being hit. Depends where in the head he was hit of course.
I think this was a little excessive. I can see shooting for a whole second or two after the man falls to the ground because it takes a while for the brain to process what just happened and the fear running through their heads was likely so intense that it doesn't help with complicated decision making. But when you are in second 5 and 6 of the shooting it is harder to justify continuing to fire. I was really worried for the people running away in the background. If you ever see a police chase that ends in a crash it would probably be better to hide than watch.
It is hard to judge because even in the video where the man was clearly down, some of the officers might have had compromised views because they were behind cover. What they may have seen or heard could have caused them to believe the individual was still a threat. People sometimes don't realize that dash cam and body cam footage is a great witness but people often forget there is a lot it cannot or doesn't show.
A lot can be learned from the video. Taking cover is the first obvious one, stressing on shot placement is the next on I see.
There are two situations you are trained to identify when taking classes for defensive handgun use: (1) failure to obey and (2) failure to stop after being shot.
He obviously didn't obey.
He obviously didn't stop after being shot.
In this case, you can reasonably and logically assume he may be intoxicated with something interfering with his physical responses to being shot, or he may be wearing body armor -- or both. Any of those situations means he can continue to shoot at you until his body has been injured to a degree that prevents it. So, you keep shooting until he's down and is unable to continue fighting.
How many rounds is "excessive"? When shooting at a person shooting at you and moving around, you don't know if the last 10 shots missed or not, so you keep shooting. There is no "stop at n
or it's excessive" magic number rule. You shoot until the threat is stopped or until you empty your magazine -- and then reload.
Did you see how many Cops were on the scene? I read 9 discharged their weapons. 69 round is what I read was the number of rounds fired. So, the average per officer was 7.666 rounds. In a Glock 17, that's fewer than half of one magazine each.
When you break it down, it's not excessive. It's just a whole lot of Cops all shooting at once to bring down a menace to society who was in a populated area after a lengthy high speed chase. Adrenaline, a perp who refused to give up and the large number of Cops on scene account for the number of rounds. Period.