The principle of patient autonomy requires that physicians respect a competent patient's decision to forgo any medical treatment. This principle is not altered when the likely result of withholding or withdrawing a treatment is hastening the patient's death.
Opinion 2.20, "Withholding or Withdrawing Life-Sustaining Medical Treatment"
The social commitment of the physician is to sustain life and relieve suffering. Where the performance of one duty conflicts with the other, the preferences of the patient should prevail. The principle of patient autonomy requires that physicians respect the decision to forego life-sustaining treatment of a patient who possesses decision-making capacity...There is no ethical distinction between withdrawing and withholding life-sustaining treatment. A competent, adult patient may, in advance, formulate and provide a valid consent to the withholding or withdrawal of life-support systems in the event that injury or illness renders that individual incompetent to make such a decision. A patient may also appoint a surrogate decision maker in accordance with state law. If the patient receiving life-sustaining treatment is incompetent, a surrogate decision maker should be identified...Though the surrogate's decision for the incompetent patient should almost always be accepted by the physician, there are...situations that may require either institutional or judicial review and/or intervention in the decision-making process...When there are disputes among family members or between family and health care providers, the use of ethics committees specifically designed to facilitate sound decision making is recommended before resorting to the courts...Even if the patient is not terminally ill or permanently unconscious, it is not unethical to discontinue all means of life-sustaining medical treatment in accordance with a proper substituted judgment or best interests analysis.
Decisions to forgo life-sustaining treatment, which so profoundly affect a patient's well-being, cannot be made independent of a patient's subjective preferences and values. Many types of life-sustaining treatments are burdensome and invasive, so that the choice for the patient is not simply a choice between life and death. When a patient is dying of cancer, for example, a decision may have to be made whether to use a regimen of chemotherapy that might prolong life for several additional months but also would be painful and debilitating. Patients, however, are no longer required to choose between aggressive life-sustaining or life-prolonging treatment and no treatment; medical professionals are becoming increasingly aware of the value of palliative care.
There is no ethical distinction between withdrawing and withholding life-sustaining treatment. A patient's right to refuse treatment is independent of whether treatment has begun.
In summary, according to the principle of respect for patient autonomy, patients who possess decision-making capacity have the right to forgo any life-sustaining treatment. Physicians must respect these patient decisions, and they must ensure that patients are well-informed about their prognoses and treatment options and understand that comfort and dignity will be top priorities whether or not they decide to forgo life support.