Whether its' a crime depends on the defendant's mental state when he did what he did. (I say that word meaning perpetrator, 'alleged perpetrator,' suspect, person who did the bad thing, or as my crim law prof would have said it "Clem" [because it was always Clem in our class hypos].)
When I say mental state, I also say that for lack of a better word, but here, mental state means one of 4 things, all of which have real legal meanings: [cut paste from wiki because I couldn't do a better job]
- Purposefully - the actor has the "conscious object" of engaging in conduct and believes and hopes that the attendant circumstances exist.
- Knowingly - the actor is certain that his conduct will lead to the result.
- Recklessly - the actor is aware that the attendant circumstances exist, but nevertheless engages in the conduct that a "law-abiding person" would have refrained from.
- Negligently - the actor is unaware of the attendant circumstances and the consequences of his conduct, but a "reasonable person" would have been aware
- Strict liability - the actor engaged in conduct and his mental state is irrelevant
All of those mental states will, with the right [or wrong] acts and set of facts get you put in the pokey.
As for negligent homicide, which is the crime you might be talking about if the actor is negligent, meaning
the actor is unaware of the attendant circumstances and the consequences of his conduct, but a "reasonable person" would have been aware, then if that conduct results in the death of another person, yes, that's going to be a crime.
Now, will it result in jail time? Prison? A suspended sentence? That depends on the prosecutor, the judge, the defense lawyer and in rare cases, the jury. Most likely, those folks are going to be looking at how negligent you were, what the state laws say about negligent homicide, or whether you were even negligent in killing someone. Probably, a case where you killed someone while going 55 in a 45 will not be as bad as killing someone by driving an 18-wheeler while on PCP.
ETA: The conclusion should be painfully obvious as to what happens in the areas above negligence, i.e., knowingly, intentionally, recklessly; so I didn't discuss 'em.
Here are two hypos so you can see the difference:
1) Clem is driving, a person runs out into the street right in front of him. Clem had no way to see them coming, they shot out from between two parked cars. Though Clem is obeying all of the traffic laws and being otherwise reasonably prudent, he still runs the person over and they die. Result? Probably no crime.
2) Clem, again, is driving. He's merging into traffic on the interstate. He fails to obey a yield sign. By doing so, he causes a wreck which results in the death of another person. Result? Negligent homicide -- because failure to obey the yield sign amounts to negligence.
This all depends on state law of course. Also, it should be noted that I'm defining terms, not giving legal advice.
Threaded Mode
