Kevin O’Connor, a presidential physician during the Biden-Harris years, recently infuriated Congress by repeatedly invoking both the Fifth Amendment protection against self-incrimination and the tradition of physician-client privilege, when being grilled by a House committee about his care of patient Joseph R. Biden, and the question of when it became clear to all concerned that Biden was incapacitated. A current historical anniversary crystallizes the difference in how we treat this issue: Forty years ago this week, President Ronald Reagan was in the hospital recovering from colon surgery. He had gone under general anesthesia for an operation on July 13, before...