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The practice of organ transplantation has been wedded to the concept of brain death for most of its history. The bond between them has been the "dead-donor rule," which requires that patients be declared dead before the removal of any life-sustaining organs (such as the heart, the entire liver, or both kidneys) ( 1). Yet the declaration of death, necessary for application of the dead-donor rule, has recently been described as an issue that is "at once well settled and persistently unresolved" ( 2).

The "well settled" aspect is reflected in the enormously successful and largely uncontroversial organ transplantation programs that recover organs from brain-dead patients and save the lives of those dying from organ failure on a daily basis. The "persistently unresolved" features pertain to nagging concerns that the concept of brain death is incoherent in that it fails to correspond to any biological or philosophical understanding of death.

Were no alternatives available, we believe a rational utilitarian argument could be made for ignoring these persistently unresolved issues in the interests of preserving the transplantation enterprise. We believe, however, that the ethical foundations of organ recovery need not rest on the problematic determination of death. We instead propose that the ethics of organ donation be based on the ethical principles of nonmaleficence and respect for persons rather than on brain death and the dead-donor rule. These provide a straightforward, ethically transparent, and potentially practical method for guiding the practices surrounding organ donation.

The dead-donor rule depends on a coherent definition of death, yet that definition has proved elusive. Before the development of mechanical ventilation and modern intensive care, the definition of death was relatively straightforward-patients were dead when they ceased to have evidence of circulation, respiration, and neurologic functioning ( 3). Typically, all three of these functions are lost over a very short period of time, with the loss of any one of them quickly leading to the loss of the other two. With the development of mechanical ventilation and cardiac support devices, however, it became possible to have the continuation of respiration and circulation in the absence of any detectable neurologic functioning. Although patients in this state are comatose (unreceptive and unresponsive), they retain most of the characteristics of living beings (Table 1); there is even a spirited debate among anesthesiologists about whether they should receive anesthesia for organ procurement procedures ( 4-7). Development of the ability to sustain patients in this state has had two important consequences-it has created the possibility of procuring transplantable organs from patients while the organs are still being perfused by a beating heart, and it has made the question "when is a person dead?" much more complicated.

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In an attempt to bring clarity to these issues, in 1981 a presidential commission articulated the Uniform Determination of Death Act, which states that "An individual who has sustained either 1) irreversible cessation of circulatory and respiratory functions, or 2) irreversible cessation of all functions of the entire brain, including the brain stem, is dead" ( 8, 9). This standard, or closely related variants, has become the accepted standard for determining death and suitability for organ donation throughout the United States and much of the world ( 10).

Out of these developments, brain death was created as a new medical diagnosis. But what reasons are there for believing that the constellation of clinical findings that constitutes brain death actually represents the death of the individual? Although the notion that we are dead when our brains are dead may seem almost intuitively obvious, the conclusion turns out to be surprisingly problematic when examined more closely.

To begin with, even firm supporters of the concept of whole-brain death now acknowledge that many patients currently diagnosed as brain dead do not in fact have (as required by the Uniform Determination of Death Act) "irreversible cessation of all functions of the entire brain." It is widely recognized, for example, that many of these patients retain function of the posterior pituitary and other brain functions ( 11-14). Although acknowledging that the concept of whole-brain death is only "an approximation" ( 15), supporters have insisted that these residual functions can be ignored because they are not significant. However, this begs the question of which physiologic responses are to be considered "significant": it is hard to understand why we place great emphasis on the pupillary light and corneal reflexes (neurologic functions of minimal physiologic significance) and ignore the neurologic regulation of salt and water homeostasis (neurologic functions of critical physiologic significance).

One of the early reasons used to defend this particular set of clinical findings as diagnostic of death was the belief that patients with these findings inevitably had a cardiac arrest within a short period of time (usually within 1 or 2 wks), regardless of the intensity of life support that they received ( 16, 17). The inevitability of an imminent cardiac arrest was taken as evidence that these patients were already dead. The logical problem with this rationale is obvious-it confuses the fact that a person is dying with the claim that he or she is already dead; that is, it confuses a prognosis with a diagnosis.

Another popular justification for assuming that brain-dead patients are dead is based on the fact that these patients have become permanently unconscious. Indeed, this is true-there are no documented instances of a patient who met the criteria for brain death who ever regained any degree of consciousness ( 18). The problem with this rationale is not with the claim itself but with the implications that arise from this claim. Patients who are in a permanent vegetative state are also widely believed to be permanently unconscious, yet they differ from brain-dead patients in that many of them breathe adequately on their own and survive for many years, being fed through a gastrostomy tube and receiving basic nursing care ( 19, 20). If brain-dead patients are dead because they are permanently unconscious, then patients in a permanent vegetative state must also be dead. This conclusion is logically unavoidable, given the premise. However, the fact that few would be willing to treat these individuals as if they were dead (for example, by burying them) indicates that being permanently unconscious is not by itself a sufficient criterion for regarding a person as dead.

The most compelling justification for regarding brain-dead patients as being dead is based on the idea that death is the loss of the functioning of the organism "as a whole" ( 15, 21-23). The argument here is that the brain is the central organizer for the body and that when the brain can no longer provide the necessary organizational influence, the body is no longer able to oppose the entropic forces favoring disintegration. This rationale emerges from the observation noted above, that patients diagnosed as brain dead usually experience a cardiac arrest within a short period of time, and this cardiac arrest is taken to be a manifestation of the body's disintegration.

The problem with this justification is that, even if it was once true, it clearly is no longer true. Admittedly, most patients diagnosed as brain dead do experience an imminent cardiac arrest, but this is because almost all either become organ donors or have life-support withdrawn. Imminent death for these patients has thus become a self-fulfilling prophesy. But, as Shewmon ( 24) has clearly shown, if brain-dead patients are provided with life-support through the acute phase of their neurologic deterioration, cardiac arrest is now neither necessarily imminent nor certain. At the extreme, Shewmon has carefully documented prolonged somatic "survival" for >14 yrs in a patient with a clearly established diagnosis of brain death. These counterexamples indicate that even if a certain level of neurologic function is necessary to maintain the functioning of the organism as a whole, then brain-dead patients are not necessarily below that threshold. Indeed, the notion that complex systems require centralized organization is itself suspect-trees and other plants are but some examples of complex life forms that lack any type of brain or central organizer ( 25).

Furthermore, the uncertainty inherent in the diagnosis of death is fundamentally distinct from uncertainty related to other diagnoses. For all medical diagnoses except death, we believe that greater scientific knowledge will bring increasing clarity about how to make the diagnoses with ever higher levels of precision. In the case of death, however, our uncertainty is not related to the state of our scientific knowledge, but rather to different and incompatible understandings about the meaning of death. As noted above, a wide range of definitions of death have been proposed, from the permanent loss of consciousness to the loss of circulation and respiration, and each has its strengths and weaknesses depending on the medical and social context. But it is clear that we will never be able to choose between these on the basis of scientific knowledge alone.

The nature of this uncertainty means that the moment of death cannot be discovered by any scientific or logical process but must be chosen by societal consensus. The constellation of signs and symptoms that constitute brain death are clearly diagnostic of severe and irreversible brain injury but diagnostic of death only by stipulation ( 26). (cont'd)