A multitude of reasons were presented to support this definition including: uniformity of standards in law for establishing death; consumption of a familys fiscal resources for artificial life support; and legal establishment for equating brain death with death in order to proceed with organ donation.Aside from the issue of support of or dispute against brain death, there is another inherent problem in this categorical definition: the variability of its application in medical practice. In 1995, the American Academy of Neurology (AAN), established a set of criteria that became the medical standard for diagnosing neurologic death. At that time, three clinical features had to be satisfied in order to determine "irreversible cessation" of the total brain including: coma with clear etiology, cessation of breathing, and lack of brainstem reflexes. This set of criteria was then updated again most recently in 2010, but substantial discrepancies still remain across hospitals and medical specialties.The problem of defining death is especially imperative as it pertains to the dead donor rule, which could be understood as one of the following interpretations of the rule: there must be an official declaration of death in a person before starting organ procurement or that organ procurement cannot result in death of the donor. A great deal of controversy has surrounded the definition of death and the dead donor rule. Advocates of the rule believe the rule is legitimate in protecting organ donors while also countering against any moral or legal objection to organ procurement.
Critics, on the other hand, believe that the rule does not uphold the best interests of the donors and that the rule does not effectively promote organ donation. Signs
Signs of death or strong indications that a warm-blooded animal is no longer alive are:

Respiratory arrest (no breathing)
Cardiac arrest (no pulse)
Brain death (no neuronal activity)The stages that follow after death are:

Pallor mortis, paleness which happens in 15–120 minutes after death
Algor mortis, the reduction in body temperature following death. This is generally a steady decline until matching ambient temperature
Rigor mortis, the limbs of the corpse become stiff (Latin rigor) and difficult to move or manipulate
Livor mortis, a settling of the blood in the lower (dependent) portion of the body
Putrefaction, the beginning signs of decomposition
Decomposition, the reduction into simpler forms of matter, accompanied by a strong, unpleasant odor. Skeletonization, the end of decomposition, where all soft tissues have decomposed, leaving only the skeleton. Fossilization, the natural preservation of the skeletal remains formed over a very long period

Legal
The death of a person has legal consequences that may vary between different jurisdictions. A death certificate is issued in most jurisdictions, either by a doctor, or by an administrative office upon presentation of a doctors declaration of death. Misdiagnosed
There are many anecdotal references to people being declared dead by physicians and then "coming back to life", sometimes days later in their own coffin, or when embalming procedures are about to begin.