It was easy to adhere to those standards at first. "We didn't perceive any shortage of organs back in the day," says Dr. Nicholas Tilney, the Francis D. Moore professor of surgery at Harvard Medical School and one of the nation's premier kidney-transplant surgeons. "If a patient had to wait a few weeks for a kidney, that seemed long. We never foresaw the kind of situation we have today."

Conditions began to change in the 90's. Seat-belt use was more common by then, and fewer Americans were dying of head injuries, depriving transplantation of its most reliable sources of pristine organs. At the same time, the demand for transplants was growing. Surgeons had little choice but to start looking to alternative sources for organs. On April 28, 2004, William Beed Jr. complained to his mother that he was feeling sick. "He couldn't swallow," his mother, Judy, a practical nurse, recalled when I spoke with her earlier this year. They decided he should go to an emergency room, she said, and the doctors there examined him and sent him home with medication, saying he was dehydrated. By that evening, he was drooling, throwing up, shaking and still having difficulty swallowing. His fever was rising. He started vomiting blood. His father drove him to another E.R.

Diagnosis is often a matter of context. Because of doctor-patient confidentiality rules, doctors involved with this case would not talk about it on the record, but a few did say that had Beed not had cocaine in his blood, the E.R. doctors might have investigated his symptoms more aggressively instead of assuming he had overdosed. (Because no autopsy was done, doctors have not been able to establish whether the rabies or the drugs actually killed him.)

Soon after, Beed fell into a coma and was put on a ventilator. After a few days, his mother said, the doctors told her and her family that their son was brain-dead. Transplant surgeons use organs from brain-dead patients because they still have a heartbeat, and if the patients are placed on a ventilator, their organs continue to get oxygen. Without oxygen, the organs degrade within minutes.

According to Judy Beed, a transplant coordinator approached her and asked whether she would be willing to donate her son's organs. She agreed, and in the middle of the night on May 4, the parents of Joshua Hightower received a phone call offering them William Beed's kidney.

Joshua Hightower, who lived in Gilmer, Tex., had had kidney problems since he was 2. They had grown progressively worse over the years. "When he was 16, things got really bad," said his mother, Jennifer Hightower, a special education assistant in the public schools, when I met with her in February. "He was pale and droopy. He weighed 112 pounds. He was sleeping all the time." His teachers at Gilmer High School walked him up and down the halls between classes to help him stay awake. A doctor urged his parents to get him on the waiting list for a kidney. In the meantime, Joshua began daily dialysis at home. The process, which purified his blood of toxins, required that he be home every evening by 10. Once there, he was tethered to the dialysis machine for between 9 and 16 hours. When the Hightowers received the call from the hospital, they jumped at the opportunity.

It is impossible to know now when the first less-than-pristine organ was retrieved and transplanted. But over the course of the 90's, according to surgeons I spoke with, many barriers fell. Age was almost certainly the first to go. Instead of accepting donors 45 and younger, some transplant centers began, gradually, to take those who were 48, 49, 50 and then up from there. "I wrote a paper for The Journal of the American Medical Association back in 1989," Dr. Lewis Teperman, director of transplantation at New York University Medical Center, told me when I talked to him earlier in the spring. "It was looking at the outcomes of using older donors. By older donors, we meant someone over 60. That was considered really, really old." Recently, N.Y.U. transplanted a liver from a deceased 80-year-old. A couple of years ago, a Canadian hospital used a 93-year-old liver from a deceased donor.