However there are some cases, perhaps many cases, where it will not be obvious to an unqualified layman whether someone is alive or dead. In these cases it is the decision of competent physicians that decides the issue. Prior to about 1960, a person would be declared dead if both their heartbeat and breathing had ceased and could not be re-initiated. But newer technological developments made this definition invalid. Heart pacemakers can keep the heart beating indefinitely long after all other internal systems have wound down.
Respirators can keep the person apparently breathing forever.
That is, there is no major central nervous system activity and there is no detectable electrical activity in the brain's cerebral cortex. At this point, the person may be declared dead in many jurisdictions. The patient may appear to be breathing, as a result of the action of a respirator. The great rise of transplant medicine has, then, been wholly dependent upon organ harvesting from so called ' beating-heart cadavers ', that is, patients who are determined to be dead on the basis of brain death criteria. In almost all cases, an infant is born alive.