Dr. Ezekiel Emanuel, health adviser to President Barack Obama, is under scrutiny. As a bioethicist, he has written extensively about who should get medical care, who should decide, and whose life is worth saving. Dr. Emanuel is part of a school of thought that redefines a physician’s duty, insisting that it includes working for the greater good of society instead of focusing only on a patient’s needs. Many physicians find that view dangerous, and most Americans are likely to agree.

The health...