Capacity vs competence is one of those ethics concepts that feels “obvious” until a vignette forces you to pick between five plausible-sounding answer choices. On exams (and on the wards), the key is knowing who decides what, when, and using which standard—and then spotting the distractors that misuse those roles.
Tag: Ethics > Medical Ethics & Law
The Big Idea (Exam-Ready)
- Capacity = a clinical determination about a patient’s ability to make a specific medical decision at a specific time.
- Determined by the treating clinician (often the primary team; psychiatry may assist but usually doesn’t “own” the call).
- Decision-specific and fluctuates (delirium, intoxication, hypoxia, pain, meds).
- Competence = a legal determination about a person’s global ability to make decisions.
- Determined by a judge/court.
- Typically broader and more durable than capacity.
High-yield phrasing:
All competent people are presumed to have capacity, but a patient may lack capacity temporarily despite being legally competent.
Clinical Vignette (Q-Bank Style)
A 68-year-old man with diabetes and COPD is admitted with pneumonia. He is febrile, tachypneic, and intermittently confused. The team recommends IV antibiotics and supplemental oxygen. He says, “No hospitals, no needles,” and tries to leave. When asked to explain the risks of leaving, he says, “I’m fine, I just need to go home because the TV is watching me.” His daughter arrives and insists he always refuses medical care and that the team must respect his choice.
Question: What is the most appropriate next step?
Answer choices
A. Respect his refusal because adults have the right to refuse treatment
B. Determine whether he has capacity to refuse treatment for pneumonia
C. Obtain a psychiatry consult to determine whether he is competent
D. Ask the daughter to consent because next of kin is the default decision-maker
E. Seek a court order to declare him incompetent before providing treatment
Correct Answer: B. Determine whether he has capacity to refuse treatment for pneumonia
This patient is demonstrating possible delirium/psychosis-like thinking in the context of acute illness (infection, hypoxia), with disorganized reasoning (“TV is watching me”) that interferes with decision-making. Before honoring refusal or overriding it, you must assess capacity for this specific decision right now.
The 4 abilities model (high-yield capacity framework)
A patient has capacity if they can:
- Communicate a choice (consistent, stable enough to act on)
- Understand relevant information (diagnosis, proposed treatment, risks/benefits)
- Appreciate how that information applies to their situation (insight—not “this doesn’t apply to me”)
- Reason about options (compare risks/benefits rationally, explain thought process)
In the vignette, he likely fails appreciation and reasoning due to paranoia/delirium.
What you do after the capacity assessment
- If he has capacity: respect his refusal, even if it seems unwise.
- If he lacks capacity:
- Treat urgent, reversible causes (oxygen, antibiotics, fluids) under implied consent if delay risks serious harm.
- Identify a surrogate (healthcare proxy/POA first; then spouse/adult children depending on state law).
- Use substituted judgment (what he would choose) or best interest standard if preferences unknown.
Why Each Distractor Is Wrong (and Why It’s Tempting)
A. “Respect his refusal because adults have the right to refuse treatment”
Why it’s tempting: Autonomy is a core principle; Step questions love “patients can refuse.”
Why it’s wrong: The right to refuse requires capacity. Autonomy applies to informed decisions made by someone who can understand/appreciate/reason. The vignette is screaming impaired decision-making (acute confusion + paranoid belief).
Exam pearl:
- Refusal ≠ capacity. A patient can refuse while lacking capacity, especially in delirium/intoxication.
C. “Obtain a psychiatry consult to determine whether he is competent”
Why it’s tempting: Psychiatry is associated with “capacity” in students’ minds.
Why it’s wrong (two ways):
- Competence is legal, not psychiatric. Only a court declares incompetence.
- Capacity is usually determined by the treating clinician. Psych can help in difficult cases, but the team shouldn’t offload a straightforward delirium-capacity question.
High-yield nuance:
- Psych consult may be appropriate if capacity is unclear, there’s suspected severe mental illness, or you need help with documentation/risk assessment—but the concept being tested is that capacity is clinical, not legal.
D. “Ask the daughter to consent because next of kin is the default decision-maker”
Why it’s tempting: Family shows up; we want “someone to sign.”
Why it’s wrong: You can’t jump to surrogate consent until you establish the patient lacks capacity. Adults are presumed to have capacity unless proven otherwise for that decision.
Also, “next of kin” is not always the first decision-maker:
- First priority is typically appointed healthcare proxy/POA (if documented)
- Then a state-specific hierarchy (often spouse → adult children → parents → siblings, etc.)
Exam pearl:
- Surrogate decision-making is triggered by lack of capacity, not by family presence.
E. “Seek a court order to declare him incompetent before providing treatment”
Why it’s tempting: Sounds legally cautious.
Why it’s wrong: Courts are slow, and emergencies are fast. If the patient lacks capacity and delay risks serious harm, you treat under implied consent. Court involvement is reserved for non-emergent disputes, complex cases, or when there is no appropriate surrogate and ongoing decisions are needed.
High-yield:
- Emergency + no capacity + no time → implied consent.
- Court orders are for competence/guardianship or contentious/ongoing situations, not initial stabilization.
Capacity vs Competence: Quick Comparison Table
| Feature | Capacity | Competence |
|---|---|---|
| Type | Clinical/medical | Legal/judicial |
| Determined by | Treating clinician (psych may assist) | Judge/court |
| Scope | Decision-specific | Global decision-making ability |
| Changes over time? | Yes (fluctuates) | Usually more stable |
| Common Step triggers | Delirium, intoxication, hypoxia, dementia, psychosis | Guardianship, legal rulings, conservatorship |
How USMLE Tests This (Patterns to Recognize)
1) The “psych patient refusing care” trap
- A psychiatric diagnosis does not automatically remove capacity.
- Ask: can they understand, appreciate, reason, communicate about this decision?
2) The “unwise choice” trap
- Patients can make choices you dislike. Capacity is about process, not outcome.
- Refusing transfusion for religious reasons can be a capacitous refusal if the patient meets the criteria.
3) The “delirium is reversible” clue
- Delirium suggests impaired capacity and a need to treat underlying causes (infection, hypoxia, meds).
- Capacity may improve after stabilization—reassess.
4) The “AMA discharge” vignette
Leaving against medical advice requires capacity assessment:
- If they lack capacity and are at serious risk, you can temporarily hold them for evaluation/treatment per hospital policy and state law (often framed as a medical incapacity hold, distinct from psychiatric involuntary hold).
What You Should Document (High-Yield for Real Life and Vignettes)
If the question asks about “next best step” or “best documentation,” include:
- The decision being assessed (e.g., refusing IV antibiotics for pneumonia)
- Patient’s responses showing understanding/appreciation/reasoning
- Evidence of impairment (e.g., delirium, intoxication, disorganized thought)
- The conclusion: has vs lacks capacity
- Plan: treat emergency needs, involve surrogate, reassess capacity
Mini Recap: The One-Liner to Memorize
- Capacity is a clinical, decision-specific, time-specific assessment by the clinician.
- Competence is a legal status decided by a court.
If an answer choice mixes these up, it’s almost always a distractor.
Frequently Asked Questions
What is the difference between capacity and competence?
Capacity is a clinical determination about whether a patient can make a specific medical decision at a specific time, while competence is a legal determination about a person’s global ability to make decisions. Capacity is decided by the treating clinician and can fluctuate with delirium, intoxication, hypoxia, pain, or medications. Competence is decided by a judge or court and is usually broader and more durable.
Who determines whether a patient has capacity to refuse treatment?
The treating clinician determines whether a patient has capacity to refuse treatment. Capacity is usually assessed by the primary team because it is a clinical judgment about a specific decision at a specific time. Psychiatry may assist in difficult or unclear cases, but psychiatry does not determine competence, because competence is a legal decision made only by a court.
How do you assess whether a patient has decision-making capacity?
You assess capacity by checking four abilities: the patient must be able to communicate a choice, understand relevant information, appreciate how that information applies to their own situation, and reason about the options. A patient who is acutely confused, paranoid, or delirious may fail appreciation and reasoning, even if they can still state a choice or insist on leaving.
Do you always have to respect a patient’s refusal of treatment?
No, you respect a refusal only if the patient has capacity for that decision. Adults can refuse treatment, but autonomy applies to informed decisions made by someone who can understand, appreciate, and reason about the situation. A patient may refuse while lacking capacity, especially during delirium or intoxication, so refusal itself does not prove valid decision-making capacity.
When can you treat a patient under implied consent instead of getting a court order?
You can treat under implied consent when a patient lacks capacity and delaying treatment would risk serious harm. In urgent situations, reversible problems such as hypoxia or infection can be treated without waiting for a court order. Court involvement is more appropriate for non-emergent disputes, complex cases, or situations where there is no appropriate surrogate and ongoing decisions are needed.