Dorland's Illustrated Medical Dictionary, 31st Edition, republished on the website of Merck & Co, defined death as (accessed May 11, 2007):
"death (death) (deth) the cessation of life; permanent cessation of all vital bodily functions. For legal and medical purposes, the following definition of death has been proposed-the irreversible cessation of all of the following: (1) total cerebral function, usually assessed by EEG as flat-line (2) spontaneous function of the respiratory system, and (3) spontaneous function of the circulatory system...
brain d[eath]. irreversible brain damage as manifested by absolute unresponsiveness to all stimuli, absence of all spontaneous muscle activity, including respiration, shivering, etc., and an isoelectric electroencephalogram for 30 minutes, all in the absence of hypothermia or intoxication by central nervous system depressants. Called also irreversible coma and cerebral d[eath]."
Robert Kastenbaum, PhD, Professor of Communications at Arizona State University, wrote in a 1989 encyclopedia entry titled "Definitions of Death," published in the Encyclopedia of Death and Dying, that:
"In the past, death has often been defined with a few confident words. For example, the first edition of Encyclopaedia Britannica informed its readership that 'DEATH is generally considered as the separation of the soul and body; in which sense it stands opposed to life, which consists in the union thereof' (1768, v. 2, p. 309). The confidence and concision had dissolved by the time the fifteenth edition appeared in 1973. The entry on death had expanded to more than thirty times the original length. The earlier definition was not mentioned, and the alternative that death is simply the absence of life was dismissed as an empty negative. Readers seeking a clear and accurate definition were met instead with the admission that death 'can only be conjectured' and is 'the supreme puzzle of poets' (1973, v. 5, p. 526).
This shift from confidence to admission of ignorance is extraordinary not only because death is such a familiar term, but also because so much new scientific knowledge has been acquired since the eighteenth century. Actually, the advances in biomedical knowledge and technology have contributed greatly to the complexity that surrounds the concept and therefore the definition of death in the twenty-first century. Furthermore, the definition of death has become a crucial element in family, ethical, religious, legal, economic, and policy-making decisions."
David DeGrazia, PhD, Associate Professor of Philosophy at George Washington University, in a 1998 article entitled "Biology, Consciousness and the Definition of Death," published by the University of Maryland's Institute for Philosophy and Public Policy Quarterly, wrote:
"When does a human life end? This question used to be answered quite easily. According to the traditional standard, which has only recently been questioned, a human being is dead when her heart and lungs have irreversibly ceased to function…
Today, however…a patient may lose consciousness a decade or more before his heart and lungs fail, for example...
Two landmark reports helped to generate a movement away from exclusive reliance on the traditional standard: the 1968 report of the Harvard Medical School Ad Hoc Committee and a 1981 presidential commission report, Defining Death. This second document included what became the Uniform Determination of Death Act (UDDA). Today all fifty states and the District of Columbia follow the UDDA in recognizing whole-brain death - irreversible cessation of all functions of the entire brain - as a legal standard of death… If a patient's entire brain is nonfunctioning, so that breathing and heartbeat are maintained only by artificial life-supports, that patient meets the whole-brain standard of death."
The Uniform Determination of Death Act (UDDA), drafted in 1980 by the National Conference of Commissioners on Uniform State Laws to provide "comprehensive bases for determining death in all situations," determined death by the following criteria:
"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. A determination of death must be made in accordance with accepted medical standards."