Assuming I already knew that they had a peanut allergy, and my intention was to hurt them, but not necessarily to kill them.
You don't specify a jurisdiction but taking the US as an example, yes you could be charged with 2nd Degree Murder - you intended to harm them but not specifically to kill them:
A second situation that constitutes second-degree murder is where the perpetrator intends only to cause serious bodily harm but knows that death could result from the act. For example, in the situation above, instead of shooting Bill, Adam grabs a shovel and whacks Bill in the head with all his strength. While Adam didn't specifically intend to kill Bill when he hit him, he did intend to strike him with the shovel knowing that such a blow to the head carried with it a distinct possibility of death. Adam killing Bill in this way would be classified as murder in the second degree.
In English law you'd be facing charges for Voluntary Manslaughter
Whoever causes the death of another human being with intent to kill that person or another...
Since there was no intent to kill, this would not apply. (Whether the prosecutor believes that there was no intent is another story; it wouldn't be surprising to have this be charged.)
It would, however, be felony murder, as battery is one of the crimes which triggers it.
@motosubatsu answered that you could be charged with 2nd degree murder because, as you also said, you "intended to harm them but not specifically to kill them".
But this is not accurate, and you could be charged with 1st degree murder, because what you "wanted" or even "expected" to happen does not equate to your "intention".
Intention is what a reasonable person (which in practice is whatever the jury decides) would expect is likely to happen as a result of the action taken, considering all of the circumstances (including your knowledge of their allergy).
So it would be up to a jury to decide:
- Whether you had knowledge of their allergy, and
- Whether their death was likely to occur as a result of your action
So if the jury decided that you knew about the allergy, and that you threw the peanuts, and that a reasonable person would think their death was likely to occur as a result, then it doesn't matter that you say after the fact that you "only wanted to harm them, not kill them", even if it is the truth, because the jury would have concluded that any reasonable person would have expected them to die as a result of the action, and so would only have taken the action if they wanted the person to die.
Note: This answer assumes that throwing peanuts at someone would likely result in their death to illustrate my understanding of "intention", but as far as I understand allergens, allergens cause the skin that they touch to swell, so allergies only cause death when the allergen is consumed through the mouth, which causes the tongue and throat to swell, which prevents breathing and causes the person to die from anaphylaxis.
It's like shooting someone in the leg which then results in their death, and saying that you only wanted to hurt them and did not expect they would die when you took that action. The point is that it's not about what you expected to happen, it's about what a jury decides a reasonable person would expect to happen in that situation (which could go either way).
It's malice, so it's murder
Malice is a desire to kill, or cause serious bodily harm (without killing them), or have reckless indifference to the danger you create. The problem is, if they actually die, that proves the danger was created and was real. Now you're up the creek; if you protest that you didn't know the danger was real, that demonstrates reckless indifference.
(unless, there was widely believed to be no danger; i.e. if the victim had had peanut allergies five times before and only got red eyes and sniffles, and didn't need further treatment, and was told by the doctor not to bother carrying an epi-pen. Then, it would be a surprise to everyone, and you could defend against a reckless indifference claim.)
This is a doctrine of law called the "eggshell skull". That concept is mainly discussed in civil law, but it applies in criminal law even moreso: If you criminally set into motion a series of events, then your shoulders bear the weight of the entire course of events, all the way to the outcome. And the outcome decides your charge. If a person dies, it's in the manslaughter/murder family.
If you beat somebody up and don't know about a blood condition that prevents healing, that's on you. If you punch someone in the nose who has severe osteoporosis and cave the skull in with a normal blow, your fault. If you roadrage someone and send them careening into a semi and they die, you go down hard. If you DUI and kill someone, it's not DUI, it's manslaughter or murder.
Once you've committed the act, it's out of your control. You ride the consequence train to wherever it goes.
Besides, if it wasn't that way, every defendant would claim to not mean to kill the victim. "I did not realize humans needed oxygen to survive".
Premeditation is separate
Once the basic type of crime is decided, then it may be "enhanced" by the idea of "aforethought", i.e. forming a plan in your mind to do the crime prior to doing it. That's the difference between murder one and murder two, in jurisdictions which call it that.
Note that courts have not set any lower limit to how much time constitutes "aforethought". It doesn't mean months or days of planning; one can develop aforethought in the minute before the crime. Being enraged, and going to the kitchen to grab a peanut could be aforethought, because grabbing the peanut is preparation.
Although you had another location in your mind, I'll cite German law.
There are several kinds of "homicide" law paragraphs, divided by intent.
- If you didn't have any intent of harming, you have "Fahrlässige Tötung (§ 222 StGB)", which roughly translates to "Negligent homicide".
- XY mit Todesfolge (several §§) can apply to several other criminal acts, e. g. rape, battery, etc., where a consequence of your deed is the death of the other person
- "Totschlag" is manslaughter, which is killing by intent
- "Mord" is killing by intent with additional qualifying properties for murder, see Murder in German law in the Wikipedia.
In the case which is described, it would probably qualify as "Körperverletzung mit Todesfolge" (§ 227 StGB): you intended to hurt the oher person, but not to kill them.