Maybe he thought it was the Hypocritic Oath?

From this great Progress Report:

Bill Frist has been positioning himself in the media as a champion for Schiavo's interests. Yet, much of Schiavo's medical care has been financed by $1,000,000 from two medical malpractice lawsuits Schiavo won after her heart attack 15 years ago. Frist has been leading the charge to limit recovery for people like Schiavo who are severely debilitated. If Frist is successful, people like Schiavo would not be able to recover any punitive damages no matter how severe their injuries.

He's also been positioning himself as a medical expert on a case about which he knows little more than than his colleagues:

In a speech last week on the Senate floor, Frist said that "speaking more as a physician than as a U.S. senator," he believed there was "insufficient information to conclude that Terri Schiavo is in a persistent vegetative state."

Frist — who as a surgeon performed more than 150 heart and lung transplants — said his conclusion was based on a review of footage of the brain-damaged Florida woman whose parents are seeking to reconnect her feeding tube. He said he also consulted court documents and spoke to a neurologist who examined Schiavo two years ago.

Frist's comments raised eyebrows in the medical community.

Although there are no official rules against the practice, ethicists said, it is generally considered unprofessional for a doctor to make or question a diagnosis on the basis of incomplete information.

"In general, physicians would consider it unprofessional for doctors to take clinical stands on issues without adequate clinical data," said Dr. Neil Wenger, head of the ethics committee at UCLA Medical Center.

William J. Winslade, a bioethicist and law professor at the Institute for the Medical Humanities at the University of Texas Medical Branch at Galveston, was more direct. Frist "has no business making a diagnosis from a video," he said.