Few expenses have risen more rapidly in recent years than the cost of illness. That may be a source of financial concern to patients and insurance companies, but not to physicians. They and their families generally get their doctoring free or at a discount from fellow physicians, who maintain a tradition known as professional courtesy. "It's just something you expect," says one doctor's wife. "It's like a Mafia —the family takes care of its own."
No one knows for sure how the practice of professional courtesy started. But it may well have begun with the 2,300-year-old Hippocratic oath, which exhorts physicians to...