We may defend another against an unjust aggressor because we can assume that the attacked person communicates to us the use of his own coactive right. If the aggressor is our own father, mother, son, or daughter, or in general any one to whom charity obliges us more than to the person attacked, we are not permitted to kill our own kin because charity does not oblige us to prefer the good of an alien to the good of one of our blood. Ordinarily we are not obliged in justice or charity to defend another at the risk of our own life. We may kill an unjust aggressor, _servatis servandis_, in defence of good equivalent in value to life: for example, to prevent life imprisonment, the loss of reason, a mutilation which would render us useless, the loss of a woman's chastity. There are cases of _accidental_ homicide, in medicine and elsewhere, which have an element of guilt in them. If a death follows accidentally upon an act which in itself is licit, and the agent uses all proper precautions, he is not morally guilty in case of an accidental death following his act. This is true even if the agent foresaw a probable death but did not intend it. If, however, the agent's primary act is illicit in itself, and an accidental death follows from this act, the agent may be guilty of homicide, provided the first act in itself is naturally likely to cause homicide. Should the first act be always dangerous, such that death commonly follows from it, like rocking a row-boat, aiming a supposedly unloaded gun at a person and pulling the trigger, striking a pregnant woman, drinking whiskey and then overlying an infant in the bed, throwing building material from a roof to a street, racing an automobile through a crowded thoroughfare, sending a crew out in a rotten ship, and so on, the accidental homicide that follows is imputable to the agent no matter how much precaution he may say he has used to avert such a death. Suppose, secondly, the original act of the agent is illicit but such that accidental death rarely follows from it; then if he takes due precaution he is not ordinarily guilty of homicide. He has, say, stolen an automobile, and is going along the street leisurely, when a careless child runs off the sidewalk under the machine and is killed. 1. No person, then, may hasten his own death or permit any one else to hasten it. 2. No physician may in any possible condition kill a patient merely to effect euthanasia. 3. The state has no more right than the physician to permit the killing of patients to bring about euthanasia.