Brain death is in some ways a logical standard for organ donation because it resolves an inherent paradox: The donor must be dead, but the organ itself alive. People who are brain dead generally have no reflexes; with life support, their organs stay healthy up until the moment they’re removed for transplant. A Harvard Medical School committee first proposed the idea of brain death in 1968—in part to resolve controversies about organ transplants— and it slowly gained acceptance. Less than one percent of people who die in hospitals are brain dead.

So in the 1990s, in response to long transplant wait lists, experts began pushing to expand the pool of potential donors. They advocated for the return of DCD, a protocol used in the early 1970s before brain death became widely accepted. In DCD, doctors remove ventilators from patients who have suffered severe brain damage but are not brain dead—like the boy in L.A.—and wait for them stop breathing on their own.

But the clock starts ticking as soon as the ventilator comes out. With every minute, the organs can deteriorate. Hearts and lungs from DCD donors are rarely viable. More resilient organs like kidneys and livers can survive 30 to 60 minutes. If the patient does not stop breathing within that time, the whole organ donation is called off.

The time pressure in DCD is part of the reason why critics have raised ethical concerns in the past. In 2007, a doctor in San Luis Obispo stood trial for attempting to hasten the death of a potential organ donor with morphine. The patient actually took seven hours to die. The doctor was eventually acquitted, but the case was a wake up call for transplant surgeons.

Over time, hospitals have refined their DCD protocols to avoid the appearance of conflict of interest. For example, doctors who care for patients are entirely separate from transplant teams who procure the organs. DCD now accounts for about 9 percent of all transplants in the U.S.

But parts of the protocol still vary hospital to hospital, because some ethical questions do not have clear answers. One issue is how far can doctors go to preserve organs before the DCD donor dies. Can they give heparin, a blood thinner, that aid preservation but does not benefit the patient? Can they stick a catheter into the patient, so their blood begins running through oxygenation machines as soon as possible after their heart stops?

These questions come up because doctors are supposed to act in their patient’s interest. “As long as a patient’s heart is beating they’re considered our patient,” says Jeremy Simon, an emergency doctor and bioethicist at Columbia University. One way to address these concerns, says Simon, is to obtain consent for these interventions from the patient or a surrogate beforehand.

Patients taken off ventilators will often gasp for air. To alleviate the pain from “air hunger,” doctors will administer painkillers, though the medical profession establishes a bright line: The dose cannot be so big as to intentionally kill the patient. (Medical experts said it was difficult to determine whether the dosage was appropriate in the L.A. case based on the few publicly available details.)