There is no single federal capacity statute. Instead, a U.S. licensee works within overlapping layers: state statutes on health care decisions, guardianship and mental health; federal rules that apply to hospitals, research and health information; professional ethics codes; and facility policy. Knowing which layer governs a question is half of answering it.

In this lesson, you will be able to

Map the state statutes and federal rules that govern capacity and substitute decisions.
Explain how the 2023 Uniform Health-Care Decisions Act is shaping state law.
Describe how federal hospital, research and privacy rules defer to state law on who may decide.

State law does most of the work

Each state sets its own rules in at least three bodies of law:

Health care decisions statutes. These define incapacity for treatment decisions, say who may determine it, set out advance directive and health care agent rules, and list default surrogates. Many states based their laws on the 1993 Uniform Health-Care Decisions Act; others developed their own models.
Guardianship (and conservatorship) codes. These govern when a court may appoint someone to make personal, medical or financial decisions for an adult, and what alternatives must be considered first.
Mental health codes. These govern emergency evaluation and involuntary psychiatric treatment, under criteria that are deliberately different from treatment incapacity.

Because the rules vary, the safe habit is to know the name of your state's statute in each area, to know where your facility's policy summarizes it, and to know who to call (ethics service, risk management or counsel) when a case does not fit.

The Uniform Health-Care Decisions Act (2023)

In July 2023 the Uniform Law Commission approved a new Uniform Health-Care Decisions Act to replace its 1993 model. States choose whether to adopt it. Delaware enacted it in Senate Bill 309, signed on September 30, 2024, and it took effect one year later, on September 30, 2025. The 2023 model is useful even outside adopting states because it reflects current thinking. According to the American Bar Association's Commission on Law and Aging, it:

defines capacity in terms of functional abilities, including whether the person could decide with support;
widens the range of health professionals who may determine that an adult lacks capacity;
sets out what happens when a patient objects to a finding of incapacity, a gap most older statutes leave open;
broadens the default surrogate list to reflect a wider range of relationships and family structures; and
authorizes advance directives limited to mental health care, including a provision that lets a person restrict their own ability to revoke the directive during an acute mental health crisis.

Check whether your state has adopted it, or is considering it, before relying on any of these features.

Federal rules that defer to state law

Federal source	What it says about substitute decisions	Practical meaning
42 CFR 482.13(b)(2), hospital Conditions of Participation	Informed decisions may be made by the patient or by a representative, but only "as allowed under State law"	The hospital must recognize whoever state law authorizes, not whoever is most insistent
45 CFR 164.502(g), HIPAA Privacy Rule	A person with authority under applicable law to make health care decisions for an adult is treated as that adult's personal representative	A valid agent or guardian can generally access and authorize use of the relevant health information; a relative without authority is not automatically a personal representative
45 CFR 46.102(i), Common Rule	A legally authorized representative is an individual or body authorized under applicable law to consent on behalf of a prospective research subject	Research enrollment of adults lacking capacity depends on state law and institutional policy, not on who happens to be present
42 CFR 489.24, EMTALA	Hospitals must take reasonable steps to obtain a written informed refusal when an individual refuses examination, treatment or transfer	A refusal is only valid if the person (or their representative) can make it; capacity matters in the emergency department

Professional ethics codes

Ethics codes add expectations on top of the law. AMA Code of Medical Ethics Opinion 2.1.2, Decisions for Adult Patients Who Lack Capacity, asks physicians to identify the appropriate surrogate, to involve patients with impaired capacity in decisions to the greatest extent possible, to support the surrogate, to apply substituted judgment and then best interest, and to consult an ethics committee when there is no surrogate, when disagreement persists, or when a surrogate's choice appears to conflict with the patient's known wishes or interests. Nursing, pharmacy, dental and allied codes express similar duties of advocacy and respect for autonomy. A board can treat a serious departure from these expectations as unprofessional conduct even when no statute was broken.

Sorting a question into the right layer

A nurse practitioner in a Delaware clinic asks three questions in one week. "Can my patient with early dementia appoint her daughter as health care agent?" is a state health care decisions question. "Can her daughter see her records?" is a HIPAA personal representative question that turns on the daughter's authority under state law. "Can I enroll her in our memory study?" is a Common Rule and institutional review board question that again turns on state law for who is a legally authorized representative. One patient, three layers, one underlying issue: who has authority, and why.

Apply it

Write down the name of your state's health care decisions statute, its guardianship code and its mental health code. If you cannot, find them today and save the links where you can reach them on shift.

Section 1 · Key points

Capacity and substitute decision rules are mainly state law, spread across health care decisions, guardianship and mental health statutes.
The 2023 Uniform Health-Care Decisions Act modernizes capacity determination, objection rights and surrogate lists; Delaware enacted it in 2024.
Federal hospital, privacy, research and emergency rules defer to state law on who may decide for a patient.
AMA Opinion 2.1.2 and other professional codes add ethical duties that boards can enforce.