Can someone give me a short summary of why police have to shoot to kill, I know its to avoid lawsuits if you paralyze/cripple someone and you have to totally eliminate the threat or whatever
It has nothing to do with that. Also, they don't shoot to kill but to incapacitate. Shooting an offender is generally either to protect the officer or protect others.
The actual action is pretty much the same, though. It's firing in short bursts at the center/core of the body, i.e. the area where vital organs are clustered. They want to fire enough times to maximize the odds of hitting something that takes the suspect down, but leave enough to fire again if it doesn't. If there are multiple officers doing this, you get the proverbial "hail of bullets."
Then they evaluate the situation after the first volley, whether the suspect is still able to return fire, etc. It's generally only excessive if the suspect is clearly incapacitated and they just keep shooting him or, obviously, do something like walk up to him and shoot him execution style in the head when he's down and unarmed.
If he's incapacitated and unarmed, they'll call for medical care.
It's a subtle distinction because the actual physical actions are pretty much the same, but it's shooting to eliminate the threat. The purpose is not to kill, per se, but it's very, very likely you'll end up dead if you escalate the situation to this point.
You can always tell people have never held or fired a gun if they ask why they didn't shoot them in the leg.
The leg is a small target to begin with & if its in motion (i.e. someone charging at you) it will be damn near impossible to get a disabling shot.
Center mass is a large & relatively stable target, a couple of shots on target will drop just about anyone.
They also have this idea that somehow, shots in the extremities are just harmless things you shake off like you were in a Rambo movie. Hit the femoral artery in the leg and you'll bleed out in seconds just like it was your throat. That or, you can find video of shit like this all over the net, it doesn't even stop the guy.
So even if you hit the target, it not only might not work, but can kill the guy just as fast.
Hit the core and unless it's the fucking Hulk he's probably going down.