“The medical question for us now is whether the irreversible loss of all brain function is accompanied by the disintegration and loss of unity to which the Pope refers.”

In his “Is Brain Death the Death of the Human Being?,”¹ Professor Robert Spaemann makes a number of criticisms of the practice of diagnosing death by the brain criterion. In the accompanying article² I have offered criticisms of the current practice of diagnosing it by the clinical criteria alone, but have defended the teaching of Pope John Paul II on the issue of death by the brain criterion. To some extent at least, the criticisms that Alan Shewmon has made, to which Spaemann adverts, are also applicable to the current practice in many Western countries, especially the English-speaking ones, but not necessarily the concept itself.

This issue is confusing because there is some fluidity about the terms being used. I understand death by the brain criterion to mean complete and irreversible loss of all function of the brain. That is the way in which it is legally defined in most jurisdictions. I have argued that testing to ensure that there is no blood flow to the brain ensures that the loss of all brain function has occurred. It has not necessarily occurred if the clinical criteria alone are used. Several countries use the blood flow test as the standard, but most English-speaking countries rely on the clinical criteria alone in most instances.

Reliance on the clinical criteria alone allows the diagnosis of death on the basis of the absence of some brainstem reflexes, the history of the trauma, and the absence of circumstances that might mask the brainstem reflexes. In those circumstances the person might still retain some brain function. In fact, as I explained, many patients diagnosed by the brain criterion using the clinical criteria alone will retain some midbrain functions and the evidence for that is the absence of diabetes insipidus in those cases. There are some other brain mediated functions such as control of blood pressure, which may also be maintained in someone who has been diagnosed by the clinical criteria alone.