Is it unlawful to kill in a motor vehicle accident?

killing is unlawful either when one commits a misdemeanor or infraction (an unlawful act, not amounting to a felony) or when one commits a negligent act (a lawful act in an unlawful manner)." People v. Thompson, 79 Cal. App.4th 40, 53 (2000).

However, even if the prosecution "fails to prove that the defendant committed a Vehicle Code violation (i.e., unlawful act), the jury may still convict the defendant of gross vehicular manslaughter 'if it finds that the defendant drove in a grossly negligent manner and, that this conduct was the proximate cause of death." Id. "[T]he distinction between an 'unlawful act' and a 'lawful act' done in an 'unlawful manner' tends to disappear in the context of vehicular manslaughter.... The act or neglect of duty which satisfies the actus reus element of the offense may in some situations also constitute gross negligence, satisfying that element as well. It is, however, established that the fact that a defendant drives a motor vehicle while under the influence of alcohol and violates a traffic law is insufficient to constitute gross negligence." People v. Hansen, 10 Cal.App.4th 1065, 1075 (1992).