Are Killing and Letting Die Morally Different in Medical Contexts?

On this issue intuitions seem to lead in opposite directions. On the one hand, we confront examples in which killing clearly seems morally differ-ent from letting die: A. A patient with terminal bone cancer and severe emphysema is expected to live at most only one month with severe intractable pain. The patient often fervently expresses a wish for death. A respiratory complication develops, and now it appears that she will die within an hour if we do not put her on a respirator. She will also die immediately if we inject air into her veins. Most of us quickly react: though perhaps we ought to withhold the respirator, we should not kill. Dinello (1975, my paraphrase) provides another example: B. Jones cannot live longer than two hours unless he gets a heart transplant. Smith is dying of an infection in his sole kidney, and without a kidney transplant, he will die in four hours. When Jones dies one of his kidneys can be transplanted to Smith, or Smith can be killed and his heart transplanted to Jones. There are no other hearts or kidneys available. To Dinello (1975, p. 358) "it seems clear that it would, in fact, be wron