Capacity vs. Competence: How to Tell Them Apart
Capacity and competence are often used interchangeably in conversation, but on the USMLE they are distinct concepts that both address a patient's ability to make decisions about their care and affairs. The core axis that separates them is WHO makes the determination and HOW broad it is: capacity is a clinical, decision-specific assessment performed by a physician at the bedside, whereas competence is a broad legal determination about managing one's affairs, made by a court.
How to tell them apart
| Feature | Capacity | Competence |
|---|---|---|
| Definition | Clinical assessment of the ability to make THIS specific decision | Legal determination of the ability to manage one's affairs |
| Who determines | The physician (assessed at the bedside) | The court (legal proceeding) |
| Nature of the judgment | Clinical judgment | Legal judgment |
| Scope | Decision-specific — it applies to a particular choice, not to the person globally | Global — pertains to the person's overall ability to manage their affairs |
| Setting | Made in the clinical encounter, often urgently (e.g., a patient refusing catheterization) | Made through the legal system / court process |
| How it is established | Demonstrated through the four components: understanding, appreciation, reasoning, and expression of a choice | Adjudicated by a court determining the person's legal status |
The reasoning
Anchor on two questions: who is making the determination, and how broad is it? If a physician is deciding whether a patient can understand, appreciate, reason about, and express a choice for a particular treatment, you are dealing with capacity — and capacity is decision-specific. If a court is deciding whether a person can manage their affairs generally, you are dealing with competence. When a case describes a physician assessing a bedside decision, choose capacity; when it describes a legal or court determination of overall status, choose competence. Remember that a patient's disagreement with the physician's recommendation does NOT equal lack of capacity: a calm, oriented adult who understands the risks and refuses treatment consistent with their values retains capacity, and their informed refusal must be respected.
Key tests
- Four-component capacity assessment (understanding, appreciation, reasoning, expression): the physician uses this bedside evaluation to establish CAPACITY for a specific decision; it is not the tool used to establish competence, which is decided in court.
- Determining WHO is evaluating: if a physician is judging ability to make a medical decision, the question is capacity; if a court is adjudicating overall ability to manage affairs, the question is competence.
- Psychiatric evaluation: indicated only when there is concern that a psychiatric illness is impairing capacity for a decision (not triggered by disagreement or religious belief alone); it informs the clinical capacity assessment, not the legal competence determination.
What they share
- Both address a person's ability to make decisions about their own health and affairs
- Both are prerequisites underlying valid, informed, autonomous decision-making
- Both can support a patient's right to accept or refuse treatment, including lifesaving treatment
Pitfalls
- Using the terms interchangeably: they are related but distinct — capacity is clinical and decision-specific, competence is legal and global.
- Assuming that refusal of recommended treatment means the patient lacks capacity — disagreement with the physician does not equal incapacity.
- Contacting a judge to override a capacitated adult's own medical decision: a court/competence determination is not the appropriate step for a competent adult refusing treatment for themselves.
- Ordering psychiatric evaluation reflexively: capacity is not questioned on the basis of religious belief alone, only when psychiatric illness may be impairing the decision.
- Treating capacity as all-or-nothing: a patient may have capacity for one decision but not another because capacity is specific to the decision at hand.
Practice this the way the exam tests it — on branching cases where your decisions shape the patient.