We do not believe that the rule of double effect can be reduced to the distinction between physical and existential suffering. This distinction is important in applying the proportionality clause in the rule of double effect, but the rule should not be identified with this clause. Nor do we deny that this rule is controversial or that it is sometimes difficult to apply. But like any other moral rule, neither the fact that it can be misapplied nor the fact that it has its origins in religious thought establishes it as invalid. Properly understood, the rule of double effect holds that it is wrong for a clinician to intend to make a patient permanently unconscious as a means of treating his suffering. It does not forbid risking permanent unconsciousness as an unintended side effect of treating suffering occasioned by severe symptoms, such as dyspnea. Nor does it forbid respite sedation, which is intended to reduce consciousness temporarily. A distinction between primary and secondary sedation is an interesting suggestion and deserves further discussion. However, the rule of double effect could still be used to justify benzodiazepine coma for refractory delirium, even if the drugs do not treat the underlying delirium, because the clinician is aiming to eliminate hallucinations and agitation.

The distinction between physical and existential suffering does not rest on any mind–body dualism, archaic or otherwise (1). This distinction is readily acknowledged in the treatment of nonterminal patients (2), and, increasingly, research in palliative medicine has begun to discriminate among different kinds of terminal suffering (3, 4). This research has important and insufficiently appreciated implications for the proper treatment of suffering at the end of life. In particular, there has been a tendency in the medical literature on terminal sedation to view terminal suffering as sui generis. Unlike that of other patients, the suffering of the terminally ill has all too often been presented as an undifferentiated phenomenon. We believe this to be a serious mistake.

Regarding the principle of collaboration and its application to practices such as voluntarily stopping eating and drinking, it is crucial to realize that clinicians are implicated in the decision to inform patients of this option. This means that if it is wrong for a patient to engage in this practice, then it is wrong for a physician to inform the patient of the option. Clinicians do not avoid the moral difficulties associated with voluntarily stopping eating and drinking by claiming that they merely informed the patient of the option and let him or her choose to engage in it.

It is true that terminal sedation and voluntary stopping of eating and drinking can be combined and that this may raise further ethical questions than either practice alone. However, once a patient has been sedated, a further ethical problem does not result from his incapacity to change his mind. As long as the initial decision to sedate is ethically justified (that is, it meets the conditions we defined as sedation of the imminently dying), then the withholding of food and fluids may be permissible. Clinicians are not required to take disproportionately burdensome steps to keep sedated, imminently dying patients alive.