 For the most part, such questions did not clamor for public attention until well into the twentieth century. (For historical background, see Pernick 1999 and Capron 1999, 120–124.) Sufficient destruction of the brain, including the brainstem, ensured respiratory failure leading quickly to terminal cardiac arrest. Conversely, prolonged cardiopulmonary failure inevitably led to total, irreversible loss of brain function. With the invention of mechanical respirators in the 1950s, however, it became possible for a previously lethal extent of brain damage to coexist with continued cardiopulmonary functioning, sustaining the functioning of other organs. Was such a patient alive or dead? The widespread dissemination in the 1960s of such technologies as mechanical respirators and defibrillators to restore cardiac function highlighted the possibility of separating cardiopulmonary and neurological functioning. Quite rapidly the questions of what constituted human death and how we could determine its occurrence had emerged as issues both philosophically rich and urgent.