KIE: A sliding-scale model for assessing patient competency to consent to medical treatments is proposed. The least stringent standard, to be applied in the case of safe and effective treatments, assumes a valid consent if the patient is aware of what is happening and assents to the rational expectations of the physician. The second standard, applicable in the case of less certain treatments, requires that the patient understand the treatment options and have the capacity to choose or reject a treatment based on a weighing of risks and benefits. The third and most stringent standard, reserved for very dangerous treatments, bases competence to consent on an appreciation of the implications of the medical information for the patient's life and on an ability to state the reasons for the decision in terms of the medical issues and the patient's personal values.