If you breach a duty, causing harm (in this case death), you are entering the world of negligence. If a reasonable person should have known that the action could cause harm, and it does, that is negligence. Negligence can be criminal. Note that this is dependent on a duty to aid. There is no duty to aid total strangers in American law. However, if you give a person a ride in your car, you have taken on a duty. If you seclude people from the aid of others, you also have a duty to provide the aid you have prevented others from offering. In addition, there IS an implied duty to aid family members.
However, the theory of negligence does not imply any real intent to harm – negligent is the lowest “culpable mental state” out there (some disagree that it should be the basis of a crime). Usually, people in this situation are merely “criminally stupid.” People whose children overheat and die in cars usually fall into this category.
If your action exceeds negligence – for example if you knew that those temperatures could kill, but did it anyway – then you reach the mental state of Recklessness. Recklessness also does not require any purpose to kill a person, but you do have to evince an understanding that your actions could result in death. Depending on state law, Reckless Indifference to Human Life is a serious charge. In New York State, under the “Extreme Reckless (Depraved) Indifference to Human Life” theory it can go as high as 2nd Degree Murder.
What if she gets out of the car in order to throw a tantrum or stomp around or otherwise prove a point in a juvenile way, and then you drive away?
Also, what if there’s no snowstorm, no immediately threatening environmental condition, except that you’re just like way out in the boonies? Say, the cornfield where James Stewart got buzzed by the cropduster. There’s no phone, her purse is in the car, basically she’s walking, but more or less physically safe, and you just abandon her.
Also: is the situation different if it’s not your spouse, but your child?
She went there, under the assumption that she would be going back via car! Taking away her ability to safely return is unethical at the least. I am leaning more towards it being manslaughter though, if the person driving away knows that the weather/terrain is hazardous enough that death is very possible. If anything bad happens to her, the husband is culpable.
I did this to my wife back when we were 16 (except it was a warm summer day, not a freezing night or a blizzard). I did something that made her mad while I was driving us home from Kmart and she smacked me, so I pulled over and told her to get out of the car because it was unsafe to be hitting the driver and blah blah blah. She got out and her sister in the back seat went too. I turned around at the next place I could, a couple miles down the road, and went back to get them … but they were gone. Nowhere to be found. I circled around between two exits on the highway for about 45 minutes before I gave up and went home, freaking out and sure they had been kidnapped by a serial killer.
Turned out a friend had seen them walking along the freeway and picked them up about two minutes after I drove off. Phew. But I learned not to kick people out of the car.
I wonder … if they’d been hit by a car and killed, would I have been legally responsible for their deaths?* It’s not like leaving somebody to die in a freezing blizzard, but it’s not totally unforeseeable, either…
*Aside from the fact that I probably would have killed myself if that happened, I mean.