 When a patient is decisionally impaired or incapacitated, ethical dilemmas concerning medical decision-making arise: Should the patient be included in decision-making in a limited way, to the best of her abilities, or should paternalistic decision-making take over? Should a proxy decision-maker make choices on the basis of the patient's best interest, or by simulating as best she can the autonomous decision that the patient would have made, had she been in a position to make one? Such issues are familiar in the context of end of life care and care for children and the cognitively impaired.