3. Mens rea: There must be an accompanying mental state. This mental state is often called “malice aforethought.”
a. “Malice aforethought” is term of art: However, for the defendant to have “malice aforethought,” it is not necessary either that he have “malice” towards his victim, in the usual sense of that word, or that he have thought about the killing before committing it. Instead, the phrase is a term of art, and can be satisfied by a number of quite distinct mental states. These states, discussed in sequence below, include (depending on the jurisdiction): (1) intent to kill; (2) intent to commit grievous bodily injury; (3) reckless indifference to the value of human life; and (4) intent to commit any of certain non-homicide felonies.
4. Proximate cause: There must also be a causal relationship between the defendant’s act and the victim’s death. The defendant’s conduct must be both the “cause in fact” of the death and also its “proximate” cause. The existence of the necessary causal relationship is determined in substantially the same way in murder cases as in other sorts of criminal cases; see the chapter on Causation, supra, p. 55.
a. Year-and-a-day rule: One special rule of proximate cause that applies only in murder cases is the requirement, still imposed in many jurisdictions, that the victim die within a year and a day of the defendant’s conduct. This rule dates back to a time when the quality of medical care was so poor and the usual life expectancy so short, that if the victim lived more than a year and a day from the attack, it could not be said with reasonable certainty that intervening causes (e.g., some unrelated disease) were not more to blame for the death than the defendant. Although the rule is often condemned as being obsolete, it continues on the books of most states. See L, p. 660.
C. Intent-to-kill murder: The most common state of mind that will suffice for murder is the intent to kill. The requisite intent exists, of course, when one has the desire to bring about the death of another.
1. Substantial certainty of death: But the requisite intent also probably exists where one does not actively desire to bring about another’s death, but knows that death is substantially certain to occur.
Example: D, who is in financial straits, owns a famous painting. He has a fake version of the painting made up, and he sends it as cargo on a commercial plane. In order to collect on his insurance, he puts a bomb aboard the plane and detonates it, killing all passengers. Even if D can show that he did not desire to kill any of the passengers, he will be guilty of their murder; he knew that, if his plan was successful, they were all substantially certain to die.
2. Ill will not needed: It follows from the above example that the requisite intent to kill may exist even where D does not bear any ill will towards his victim. For another illustration, consider the case of mercy killing, set out in the next example.