Homicide: Legal Aspects

The central theme of the law of homicide is the unique value of human life. While danger to life is an element of many other crimes as well, the law of homicide focuses on it directly, by declaring criminal a wide range of conduct that actually causes a death. Because life is valued so highly, such conduct is prohibited much more generally than conduct causing other kinds of harm. Whereas the criminal law for the most part is concerned with intentional harms, criminal homicide includes not only intentional killing but also a broad range of conduct from which death results unintentionally.

Homicide is the killing of a human being by another human being. (Suicide, insofar as the criminal law deals with it, is treated separately.) A question occasionally arises whether a death satisfies this definition, either because it is not clear whether the victim was a "human being" for this purpose or because it is not clear whether another person's conduct caused the death. Most often, the fact of homicide is not an issue. The difficult questions are whether the homicide is criminal or noncriminal and, if the first, in which category of criminal homicide it belongs.

The victim a human being. When homicide is the issue, the law makes no distinctions among human beings as victims. It is human life as such that is protected, and none of the criteria of worth by which we may classify persons for other purposes is material. Death is the more or less remote end for us all, but it is no less homicide that the life cut short would soon have ended anyway, because of age, ill health, or any other reason.

No question has arisen in any adjudicated case as to whether a living creature who is the victim of a homicide was a human being or belonged to some other species. A problem of definition sometimes arises because it is necessary to determine when, in the process of prenatal or postnatal development, life as a separate human being begins or when, in the process of dying, life as a human being ends. The usual rule is that the victim of a homicide must have been "born alive." The older law required that the fetus have been fully separated from the mother and have a separate existence, including an independent circulatory system; it was sometimes also required that the umbilical cord have been cut. There has been some modification of the requirement of full separation, probably in recognition of the easier and safer conditions of ordinary childbirth. It is still generally the law that the victim must have been born alive, which means that there were signs of separate existence and that the birth was far enough advanced so that it would ordinarily have been completed successfully. The destruction of a fetus before it has reached this stage of development is covered by statutes dealing specifically with abortion or the killing of a fetus.

At the other end of a life, the availability of heroic medical techniques to sustain some of the body's vital functions, including circulation and respiration, after other functions have stopped has raised the question of when life ends. The question may be critical if an organ transplant is contemplated, because it is homicide if a human being, however near death, is killed; a successful transplant requires that the organ be removed before necrosis of tissue sets in. There is scant law to answer the question. In ordinary cases, death is deemed to have occurred when there is absence of a heartbeat and respiration. It has also been urged that irreversible coma or cortical brain death, which involves destruction of the cognitive faculties, is enough to constitute legal death, even if circulatory and respiratory action continue.

Action causing death. If someone acts with the intention to kill another person and the death occurs as he intended, there is no difficulty in establishing that his conduct is the cause of death. If he acts without intending to kill or if he has such intent but the death occurs in an unanticipated way, it may not be obvious whether his conduct or some other contributing factor for which someone else or no one else is criminally responsible should be regarded as the cause of death. Efforts to define more precisely the element of causation in homicide have not taken the law beyond what the concept of causation itself conveys. The matter is left to the trier of fact, who must decide on the basis of common sense and ordinary experience whether to attribute causal responsibility.

Since homicide is constituted by a result rather than a particular kind of action, one can commit homicide by an omission or failure to act, if the omission is the cause of death. In many situations, more than one person has an opportunity to take action that would avert death; it would be an extravagant extension of the notion of causation to say that the failure of each caused the death. Furthermore, the criminal law does not generally impose a duty to aid another, even if aid would avoid serious injury to the other and could easily and safely be given. Accordingly, criminal liability for homicide based on an omission is limited to failure to perform an act that one is otherwise legally required to perform. Liability is not based only on a moral obligation, however plain, arising from the danger to life or any other circumstance.

The most common example of such liability is the death of a dependent child resulting from a parent's failure to provide the ordinary care required by law. The relationship of marriage also imposes on each spouse a duty to care for the other that will sustain liability for homicide. Other relationships, like the employer-employee relationship or the ship's captain-seaman relationship, may also provide a basis for liability; the increasing impersonality of such relationships makes liability doubtful if there is not also some other basis of liability. A legal duty to act may be prescribed by a statute or regulation or may arise from a specific contractual undertaking or a voluntary undertaking that places the other person in one's care. Even if there was a legal duty to act, a death resulting from an omission is not a criminal homicide unless all the elements of the offense, discussed below, are also present. If a person's omission to perform a legal duty was not intentional or negligent, we should probably not describe it as having caused the death; but in any case, in the absence of the required culpability, the omission would not constitute a crime. Convictions of manslaughter by omission are not as rare as convictions of murder by omission; the latter are not, however, unknown, the most common example being a parent's failure to care for an infant who is intentionally left to die.

When the failure to perform a legal duty manifests the same culpability that establishes liability for an act that causes death, liability for the omission, if death results, is unproblematic. One whose grossly negligent failure to act causes a death is not less guilty than one whose grossly negligent act causes a death. Similarly, if a person's legal duty to act has the effect that no one else will probably act in his place, his deliberate nonperformance with the intent to cause death is not very different from a deliberate act. It may not, however, always be possible to establish a close equivalence between acts and omissions. Doubts of this kind, if they arise, are resolved as part of the requirement that the omission in question be the cause of death.

The notion of causation is usually used disjunctively. Ordinarily, a conclusion that one person has killed another precludes a conclusion that another person's separate conduct has brought about the same death. Provided that the element of causing the death of another is satisfied in each case, there is no rule prohibiting more than one person from being criminally liable for the same death. If both parents of a child, each acting independently, failed to give him adequate care and the child died as a result, they might both be guilty of homicide. Similarly, in theory two persons whose independent acts were each the cause of another's death might both be liable.

Most American jurisdictions have preserved a common law rule that a person cannot be convicted of homicide unless the death occurs within a year and a day after the conduct alleged to have caused the death. The purpose of the rule is to avoid a conviction if the passage of time has rendered the element of causation uncertain. Taking account of advances in medical science, the Model Penal Code and the law of some states have abandoned the rule.

Noncriminal and criminal homicide. Despite the value of life, the law recognizes that in some circumstances other values prevail. The official carrying out of a sentence of death, for example, is a deliberate, carefully planned homicide pursuant to the authority of the state. Killing an enemy in battle during war is another example of justifiable homicide, which the state not only permits but approves. There are in addition a number of situations in which the use of deadly force is permitted even though there is no official purpose to take life. In certain circumstances, deadly force can be used to defend oneself or others against the threat of death or serious injury or to prevent commission of a felony or the escape of a felon. The combination of another strongly supported value and the unavoidable necessity of risking life to protect that value excuses the homicide. If life is not taken intentionally, there is no criminal liability unless the actor's conduct is culpable to the extent specified by the categories of unintentional criminal homicide, the least of which requires substantial negligence. Many unforeseen deaths that can be traced causally to the conduct of a particular person occur simply as accidents for which no one is criminally responsible.

Criminal homicide is everywhere divided into categories that reflect the historical distinction in English law between murder and manslaughter. American statutory formulations have varied the terminology and the precise classifications; many statutes create more than two forms of criminal homicide, for purposes of definition and/or punishment. These variations notwithstanding, it is usually possible to discern a category that corresponds to the common law crime of murder, the paradigm of which is a deliberate killing without legal justification or excuse, and a category that corresponds to the common law crime of manslaughter and comprises killings that either are committed in circumstances which substantially mitigate their intentional aspect or are not intentional. In common speech as well as in the law, murder refers to the most serious criminal homicides, and manslaughter to those that may be serious crimes for which a substantial penalty is imposed but lack the special gravity of murder.