There is no element of intent in self defense. There never has been. It simply makes no sense. Intent comes into play when deciding what degree of homicide it was.
You seem to be going by the assumption that everyone involved will agree that it is self defense.
Suppose you kill someone in self defense. It may be justifiable, but maybe the evidence at the scene isn't so clear cut. An overzealous DA decides to prosecute you for murder.
I found the following
definition of first degree murder (emphasis mine):
MURDER, FIRST DEGREE - In order for someone to be found guilty of first degree murder the government must prove that the person killed another person; the person killed the other person with malice aforethought; and the killing was premeditated.
To kill with malice aforethought means to kill either deliberately and intentionally or recklessly with extreme disregard for human life.
Premeditation means with planning or deliberation. The amount of time needed for premeditation of a killing depends on the person and the circumstances. It must be long enough, after forming the intent to kill, for the killer to have been fully conscious of the intent and to have considered the killing.
Do you think that
intent will or will not be a factor in the trial?
Do you think that your statements about "shooting to kill" will be helpful to your defense, considering that the prosecutor will be trying to prove that you intentionally killed another human being?
Leathal force is generally permitted when you are faced with an immediate and otherwise unavoidable threat of death or grave injury. When, faced with such a threat, we employ lethal force to stop that threat.
We shoot to stop. Not to stop the VCA. To stop the threat.
The reason you can't shoot him after he drops his gun is because he no longer presents an imminent deadly threat. It has nothing to do with whether you were shooting to kill in the first place.
If you were shooting to kill in the first place, you would keep shooting untill you had killed him. The fact that you would stop shooting when he drops the gun shows that you are in fact shooting to stop the threat.
Now, the target areas (COM, head) most likely to cause incapacitation, and therefore
stop the threat, just so happen to corespond to a high probablility of the VCA expiring. Oh well. Too bad for him.
But saying that you are "shooting to kill" demonstrates that you had intent to kill, and that you were conscious of that intent before aiming and pulling the trigger. I'm no lawyer, but I would think that your murder 1 defense would go a lot better without that admission.
Thread hijack aside, sometimes a headshot may be the best, or only way, to stop the threat.