Physicians can ethically withhold information in situations where full disclosure of a diagnosis or treatment would cause great psychological harm to the patient.
The history of the AMA's policy on anencephalic newborns as organ donors is a living example of what medical science can do sometimes conflicts with society's support or nonsupport of those possibilities.
Physicians need to understand when it may be appropriate to let patients get involved in medical decision-making and when it may be necessary to provide their personal medical judgment.