Most Jehovah's Witnesses believe human blood is sacred and would not accept transfused blood. In the otherwise competent adult with capacity, courts have ruled that physicians cannot be held liable for complying with a patient's directive and withholding life-saving blood administration after providing specific and detailed informed consent of the consequences of such an omission of treatment. The right of a Jehovah's Witness to refuse a blood transfusion is absolute and has been upheld in legal cases. Clinical providers should be aware that many Jehovah's Witnesses carry a medical alert card that states their wishes regarding transfusion therapies. It is crucial that an open and honest avenue of communication exists between the patient, surgeon, and anesthesiologist in making clinical decisions.

Jehovah's Witnesses will generally refuse transfusion of whole blood, packed red blood cells, white blood cells, plasma, and platelets; however, they may allow the use of cardiopulmonary bypass, dialysis, or similar equipment, as well as intraoperative blood salvage, in which the extracorporeal circulation is uninterrupted. Their religious understanding does not absolutely prohibit albumin, immune globulins, or hemophilia therapies; those products must be decided on an individual basis. They generally accept all nonblood replacements, including nonblood colloids, crystalloids, dextrans, and oxygen-carrying blood substitutes.

An anesthesiologist can refuse to care for any patient when a procedure is elective. In an emergency, legal and ethical requirements apply. The issue of providing blood products becomes clouded when patients are deemed incompetent, are unconscious, or are minors.