 The origins of our contemporary concept of decisional capacity lie in a varied configuration of historical developments in health care law and ethics that accompany the rise of the doctrine of informed consent. According to the most well developed and widely accepted account of this doctrine, the moral purpose of requiring informed consent in certain contexts is to promote and protect the autonomy of patients and research subjects (Faden &amp; Beauchamp 1986). It is commonly observed that respect for autonomy 