The health care needed by many people, not only by the elderly, is limited for a variety of reasons. Sometimes a person does not want certain medical treatments, and it is often reasonable and morally correct for one to act on such a desire; sometimes others decide not to provide health care for a patient not capable of deciding for himself or herself, because of their judgment that such treatment does not help the patient or harms the patient more than it helps him or her. But sometimes health care is limited, not out of concern for patients' well-being or legitimate desires, but because there are not sufficient resources to provide the needed care. The moral issues raised by these different grounds for limiting health care are distinct, although, as I will suggest, they are sometimes confused. I will be focusing only on limitations based on the scarcity of health care resources.

A scarcity of health care resources can emerge within any social arrangement for providing health care. Perhaps the most obvious situations in which this happens are medical disasters when triage is called for to distribute fairly resources which, in the circumstances, are insufficient to assist all who need them.