You got me curious, so I’ve been thinking about it under Canadian criminal law. What follows is me just noodling around with the hypothetical, and is not legal advice.
Our version of manslaughter is often called “unlawful act” manslaughter. What that means is that there must have been an underlying unlawful act that contributed to the death, even in the absence of an intent to kill.
The Criminal Code also allows the use of reasonable force to protect one’s life. We don’t have a castle doctrine (at least not in the US sense; our castle doctrine relates to search warrants), but if you’re trapped in your house by an armed intruder, and can’t retreat, reasonable force can be used to protect yourself.
So let’s say that’s what happened. You used reasonable force, the intruder is out cold and bleeding out. Self-defence, so no underlying unlawful act, so it’s okay if he dies while you dither about calling 911?
Except, we also have an offence called the duty to provide necessaries of life. It generally applies to family members in your care, but there is also a more general version:
What does “under his charge” mean? I’ve not researched it, and I don’t know if the issue has ever come up, but if you’ve incapacitated someone to the point where they are detained or otherwise unable to withdraw, I can certainly see an argument that the person is under your charge, and that failure to call 911 would be a failure to provide necessities of life.
If you were to do that, and the person dies, that could potentially qualify as the unlawful act that is necessary to support a manslaughter charge.
You wouldn’t be liable for the initial self-defence, but the failure to provide necessaries (ie the 911 call), might be sufficient.
All of which is not legal advice, but just thinking about the possible legal implications of the hypothetical.