The killing—At common law life ended with cardiopulmonary arrest the total and permanent cessation of blood circulation and respiration. With advances in medical technology courts have adopted irreversible cessation of all brain function as marking the end of life
of a human being—This element presents the issue of when life begins. At common law a fetus was not a human being. Life began when the fetus passed through the birth canal and took its first breath.
by another human being—at early common law suicide was considered murder. The requirement that the person killed be someone other than the perpetrator excluded suicide from the definition of murder.
with malice aforethought—originally "malice aforethought" carried its everyday meaning—a deliberate and premeditated killing of another motivated by ill will. Murder necessarily required that an appreciable time pass between the formation and execution of the intent to kill. The courts broadened the scope of murder by eliminating the requirement of actual premeditation and deliberation as well as true malice. All that was required for malice aforethought to exist is that the perpetrator act with one of the four states of mind that constitutes "malice".
The four states of mind recognized as constituting "malice" are:
i. Intent to kill
ii. Intent to inflict grievous bodily harm short of death,
iii. Reckless indifference to an unjustifiably high risk to human life (sometimes described as an "abandoned and malignant heart"), or
iv. Intent to commit a dangerous felony (the "felony-murder" doctrine).
Under state of mind (i), intent to kill, the deadly weapon rule applies. Thus, if the defendant intentionally uses a deadly weapon or instrument against the victim, such use authorizes a permissive inference of intent to kill. Examples of deadly weapons and instruments can include but are not limited to guns, knives, deadly toxins or chemicals or gases and even vehicles when intentionally used to strike a victim....