Determining death for deceased organ donation

Darshak Sanghavi, writing a while ago in the NY Times Sunday Magazine, discusses When Does Death Start?

"Organ transplantation must abide by the so-called dead-donor rule: a person has to be declared dead before any vital organs can be removed. Yet organs have to be alive if there is any hope of successful transfer to a recipient. Medical professionals have handled this paradoxical situation — finding a dead body with live organs — by fashioning a category of people with beating hearts who are said to be brain-dead, usually after a traumatic head injury, and who are considered just as dead as if they had rigor mortis.
To diagnose brain death, doctors typically go through a checklist of about a dozen items, including assessing reflexes like blinking, coughing and breathing, which are all controlled by the brainstem. The criteria are extremely strict, and only a tiny fraction of severely brain-injured people meet them."

Before brain death, the traditional definition of death involved irreversible cessation of heart beat, and you can also donate after cardiac death (DCD), but things have to move fast, since once circulation stops the organs begin to die. "D.C.D. requires doctors to confront the shadowy question of exactly when somebody dies after the heart stops."

In the U.S., we seem to be converging on a 5-minute rule.