The 1960s were a time to question everything, and in medicine, this included the definition of death. “From ancient times down to the recent past it was clear that, when the respiration and heart stopped, the brain would die in a few minutes,” wrote anesthesiologist and medical ethicist Henry Beecher in 1968. But by the time of his writing, things had become much less clear. 

Beecher, who practiced at Massachusetts General Hospital, had gained the national spotlight for his 1966 paper “Ethics and Clinical Research.” It outlined almost two dozen cases in which subjects of medical experiments had been put in grave danger.  The paper became a landmark and led to the creation of review boards that would oversee all human experiments. 

The task facing Beecher in 1968 was, if possible, even more fraught. Recent advances had dramatically changed the possibilities at then end of life. Improvements in supportive care—especially mechanical ventilation—meant that patients could have their hearts beat indefinitely, “alive” in some new sense of the word, even when their brains were catastrophically damaged. 

Making the issue more pressing, organ transplantation capabilities were improving, with the first heart transplant performed a year earlier in South Africa. While physicians were careful not to conflate the two frontiers, a clear indication of when patients had no hope of brain recovery—or were “hopelessly unconscious”—might allow harvesting their organs in an ethical way for patients in need.  

To define a permanently nonfunctioning brain, an ad hoc group of men, most with affiliations at Harvard University, was assembled. The group included several neurologists and a transplant physician as well as a lawyer, an ethicist and a public health scholar. Their “Harvard Criteria” outlined the medical characteristics of so-called brain death. Although mental unresponsiveness was a controversial way to define death at the time, public and legal opinion gradually shifted to accept it. This was cemented in 1981 with the Uniform Determination of Death Act, which established that brain death was accepted as legal death throughout the country.

This statute has held firm, although ethical debates have continued, and one state, New Jersey, allows religious exemptions in defining death. It remains to be seen what will happen as new medical frontiers blur once-established lines.

This past summer, a team at Yale University was able to initiate activity in the brain, heart and kidney cells of a pig an hour after the animal had died. Because of the profound ethical implications of reversing brain death, the researchers used nerve blockers to forestall the possibility. But as medicine progresses, it is perhaps only a matter of time before the lines between life and death must once again be redrawn.