Cruzan v. Director, Missouri Department of Health recognized that a competent person has a constitutionally protected liberty interest in refusing unwanted medical treatment. The case also permitted a state to require clear and convincing evidence of an incapacitated patient's wishes before withdrawing life-sustaining treatment. That distinction reflects both sides of the problem: the patient's liberty matters, and the state may protect life and guard against an erroneous or unauthorized decision. A rule governing proof is not the same as a rule forcing treatment on every competent person.

Procedure often determines whether the decision is reliable. Notice, an opportunity to present medical evidence, a neutral decision maker, and review of capacity can reduce the risk of error. A claimant may also argue that government may not impose the treatment even after a flawless hearing. The first objection is procedural; the second is substantive. Available relief might require a new hearing, recognition of a valid directive, or an order against unwanted treatment, depending on the right, record, and authority established.

Federal doctrine supplies a constitutional floor, not a complete health-law code. Advance-directive statutes, informed-consent rules, professional duties, and state constitutions may protect autonomy more specifically or more broadly. A private physician's conduct also requires a source that reaches private medical care rather than an automatic Fourteenth Amendment claim. On an exam, ask who acted, what decision is at issue, whether the person is competent, which source applies, and whether the dispute concerns proof and procedure or the government's power to override the choice.

Video lesson: Due process and the right to privacy | AP US Government & Politics | Khan Academy