17.1 Principles of Bioethics & Decisional Capacity
Key Takeaways
- Primarily ethics is an enumerated subsection of the Miscellaneous blueprint category, and ethics in the elderly is a separate Geriatric Syndromes subsection.
- Capacity requires the ability to communicate a choice, understand relevant information, appreciate the situation and consequences, and reason about options.
- Capacity is decision-specific, so a patient may lack capacity for a complex choice while retaining it for a simpler one.
- A cognitive screening score does not establish or exclude capacity by itself.
- Competence is a legal determination made by a court, whereas capacity is assessed clinically by any physician.
Last updated: August 2026
Medical ethics, clinical decision-making capacity, informed consent, and surrogate decision-making represent core competencies tested extensively on the ABIM Internal Medicine Board Examination. Internists frequently encounter complex scenarios involving treatment refusal, conflicting family wishes, advance directives, and confidentiality dilemmas. Mastery of biomedical ethical frameworks and legal standards is essential for compassionate, legally sound patient care.
1. The Four Core Principles of Biomedical Ethics
Modern clinical biomedical ethics rests upon the principlism framework articulated by Tom Beauchamp and James Childress. When navigating difficult clinical dilemmas, physicians must systematically evaluate and balance four fundamental moral principles.
| Ethical Principle | Definition & Clinical Scope | Clinical Application & Tensions |
|---|---|---|
| Autonomy | Respect for the patient's moral right to self-determination, bodily integrity, and independent choice. Requires voluntary decision-making free from coercion, manipulation, or undue influence. | An adult with decision-making capacity has the absolute right to accept or refuse any proposed medical treatment, even if refusal results in disability or death. Autonomy frequently conflicts with Beneficence. |
| Beneficence | The affirmative duty of healthcare providers to act in the best interest of the patient, promote their physical and psychological well-being, and restore health. | Recommending evidence-based therapies (e.g., primary percutaneous coronary intervention for STEMI). Beneficence must never be pursued through unauthorized paternalism that overrides a competent patient's autonomy. |
| Non-Maleficence | "Primum non nocere" — First, do no harm. Obligates clinicians to avoid inflicting intentional harm, minimize procedural/pharmacologic risks, and ensure that anticipated benefits outweigh potential burdens. | Withholding non-beneficial or futile invasive interventions (e.g., CPR in terminal refractory shock) that inflict suffering without physiological benefit; deprescribing harmful polypharmacy in frail elderly patients. |
| Justice | The obligation to distribute healthcare resources, benefits, risks, and costs fairly, equitably, and non-discriminatorily across all patients and populations. | Distributive justice in allocating scarce resources (e.g., ICU beds, ECMO circuits, deceased-donor solid organs via UNOS criteria); avoiding bias based on race, socioeconomic status, gender identity, or insurance. |
2. Decisional Capacity Assessment in Clinical Practice
A. Capacity vs. Competence: Critical Legal and Clinical Distinction
- Decision-Making Capacity (Clinical): A clinical determination made by any licensed treating physician regarding a patient's ability to make a SPECIFIC medical decision at a SPECIFIC point in time. It is dynamic, decision-specific, and can fluctuate with acute physiological or neuropsychiatric changes.
- Competence (Legal): A global legal status determined solely by a judge/court of law regarding an individual's overall legal qualification to manage property, enter into contracts, or execute legal documents. All adult patients are legally presumed competent until adjudicated incompetent in a formal court hearing.
B. The Four Essential Functional Abilities Required for Capacity
To possess decision-making capacity for a given clinical choice, a patient must simultaneously demonstrate all four of the following functional criteria:
- Understanding: The ability to comprehend and recall the relevant medical facts, including the nature of the illness, proposed diagnostic tests or treatments, the anticipated prognosis, potential risks, expected benefits, and reasonable alternatives (including the consequences of no treatment).
- Bedside Inquiry: "Can you explain in your own words what condition you have and what treatment we are recommending?"
- Appreciation: The ability to apply the medical information to one's own personal situation and acknowledge that one has the illness and that the proposed treatments (or refusals) have direct, real-world consequences for oneself.
- Bedside Inquiry: "Do you believe you have this medical condition? What do you think will happen to your health if you decide not to undergo this procedure?"
- Reasoning: The ability to engage in a logical, rational thought process, compare risks and benefits, manipulate information coherently, and articulate why one choice is preferred over another in accordance with one's own personal values, goals, or beliefs.
- Bedside Inquiry: "How did you weigh the risks versus the benefits in reaching this decision? Why does this choice make the most sense for you?"
- Expressing a Choice: The ability to communicate a clear, definitive, voluntary, and stable choice over time (verbally, in writing, or via reliable non-verbal communication such as blinking, head nodding, or pointing to communication boards).
- Bedside Inquiry: "What is your final decision regarding having this surgery?"
C. The Sliding Scale Model of Capacity (Risk-Sensitive Threshold)
Capacity is not an "all-or-none" phenomenon; it operates on a sliding scale proportional to the stakes of the medical decision:
- Low Stakes / High Benefit Decisions (Low Threshold): Agreeing to a low-risk, highly effective therapy (e.g., accepting oral antibiotics for uncomplicated cellulitis or phlebotomy for routine laboratory work) requires only a basic level of understanding and assent.
- Moderate Stakes Decisions (Moderate Threshold): Deciding between two medically reasonable options with balanced risk profiles (e.g., choosing between elective laparoscopic cholecystectomy versus medical management with observation) requires standard functional understanding and comparative reasoning.
- High Stakes / Grave Consequence Decisions (High Threshold): Refusing a life-saving, low-risk therapy (e.g., refusing emergency surgical repair for a ruptured appendicitis, refusing mechanical ventilation for acute hypercapnic respiratory failure, or refusing antibiotics for bacterial meningitis) requires an exceptionally high and rigorous threshold of demonstrable appreciation, reasoning, and internal consistency.
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