"What the patient would have decided": a fundamental problem with the substituted judgment standard.

Decision making for incompetent patients is a much-discussed topic in bioethics. According to one influential decision making standard, the substituted judgment standard, the decision that ought to be made for the incompetent patient is the decision the patient would have made, had he or she been competent. Although the merits of this standard have been extensively debated, some important issues have not been sufficiently explored.