497 U.S. 261 (1990)
Cruzan v. Director, Missouri Department of Health is the U.S.
Does the Due Process Clause require a state to permit family members to withdraw life-sustaining treatment from an incompetent patient without clear and convincing evidence that the patient herself would have refused such treatment?
The Due Process Clause of the Fourteenth Amendment protects a competent person's liberty interest in refusing unwanted medical treatment. However, when a patient is incompetent and cannot exercise that right personally, a state may require clear and convincing evidence of the patient's prior expressed wishes or intent before authorizing the withdrawal of life-sustaining treatment, including artificial nutrition and hydration.
No. The Constitution does not compel a state to accept substituted judgment by family members absent clear and convincing evidence of the incompetent patient's own wishes. Missouri's requirement of clear and convincing evidence before authorizing the termination of artificial nutrition and hydration is constitutionally permissible.
Cruzan is the Supreme Court's cornerstone right-to-refuse-treatment case. It both recognizes a protected liberty interest in declining unwanted medical care and validates robust state procedural safeguards when surrogates act for incompetent patients. In practice, Cruzan catalyzed widespread adoption of living will statutes, durable powers of attorney for health care, and institutional policies clarifying end-of-life decision-making. It provides the constitutional backdrop for later decisions limiting a claimed right to assisted suicide and continues to guide courts and clinicians on evidentiary standards, surrogate authority, and the legal status of artificial nutrition and hydration. As a pedagogical matter, it teaches students to separate the existence of a substantive liberty interest from the state's power to define and enforce procedures that guard against error and abuse.