Educational draft · awaiting clinical reviewThe full textbook explains uncertainty but does not replace live national or local guidance, specialist advice, or current prescribing information.
Assess decision-specific capacity with all practicable support, identify the correct legal authority, apply valid advance refusals, and make transparent best-interests decisions that centre the person's rights, values and least restrictive clinically beneficial option.
Capacity protects autonomy by identifying who decides, not by testing whether a choice appears sensible. In England and Wales, the Mental Capacity Act presumes capacity and requires all practicable support before a person is treated as unable to decide. Assessment is specific: a person may decide where to live but not understand a highly complex operation, or may lack capacity during delirium and regain it tomorrow.
The statutory analysis has a diagnostic and functional relationship. There must be an impairment or disturbance in functioning of mind or brain, and because of it the person cannot understand, retain, use or weigh, or communicate the information relevant to the decision. Record concrete evidence, such as inability to compare the material consequence of each option after repeated explanation. A cognitive screening score neither proves nor disproves capacity.
Timing and support are active clinical duties. Treat pain, hypoxia, infection and medicine toxicity; choose the person's best time of day; provide interpreter, hearing aids, glasses, accessible language and trusted support where appropriate. If a non-urgent decision can safely wait for delirium to improve, delay may preserve autonomy. Urgent care may proceed through best interests only to the extent that delay would cause harm.
The person can explain the material facts and trade-offs consistently even though clinicians regard the selected option as risky or unwise.
Repeated inability to compare consequences or apply information to oneself may show impaired use or weighing when causally linked to mental dysfunction.
Aphasia, hearing loss, language difference or motor disability may mask capacity and requires skilled alternative communication before any conclusion.
Delirium, medication effects, mania or variable consciousness can produce periods of ability and inability, making timing and repeated assessment essential.
The document or statement identifies the refused treatment and applicable circumstances, remains unwithdrawn and satisfies extra life-sustaining formalities where required.
Conflict about validity, proxy powers, restraint or life-sustaining treatment requires senior review and may need urgent legal resolution.
The assessment asks whether the person can make this choice, not whether the clinician regards the eventual choice as prudent.
A person may repeat facts yet be unable to compare or apply consequences because frontal or psychiatric dysfunction impairs weighing.
The law does not demand long-term recall if the person can hold information long enough to use it for the decision.
Past preferences are central evidence but the decision also considers current experience, clinical options, relationships, rights and foreseeable consequences.
Time pressure should prompt early senior and legal escalation, not a contest between clinician authority and family insistence at the bedside.
Using a cognitive score as the capacity decision.
Testing capacity before providing hearing, language or communication support.
Finding incapacity because the patient chooses a risky option.
Writing that capacity is absent without identifying the functional evidence and causal impairment.
Asking next of kin to consent despite no relevant legal authority.
Treating an advance statement as identical to a binding advance refusal.
Ignoring the extra formalities for refusing life-sustaining treatment in England and Wales.
Applying England-and-Wales procedures in Scotland or Northern Ireland without local verification.
Using restraint or covert administration without necessity, proportionality and the relevant safeguards.
Delaying legal advice until an entrenched dispute reaches the point of emergency.
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An adult with renal failure accurately explains that refusing dialysis may cause death, compares alternatives and consistently communicates refusal. Family members call the decision irrational. What should the clinician do?
National guidance is shown before implementation-dependent detail. Apply principles in context and verify current guidance when a decision affects care. Source check completed 27 Aug 2026; clinical approval remains outstanding.
Editorial contact: Doctor’s Passport editorial team. Source-check date is separate from clinical approval. Report a content problem · Content changes
When capacity is absent, identify legal authority in sequence. A valid applicable advance decision to refuse treatment governs in England and Wales. A health-and-welfare lasting power of attorney or court-appointed deputy may decide only within documented scope. Without such authority, the clinician responsible for treatment makes the decision in the person's best interests after consultation. Relatives supply crucial evidence of values but do not acquire power from being named next of kin.
Best interests is a disciplined process. Avoid assumptions based on age, appearance, disability or behaviour; consider all relevant circumstances, encourage participation, identify past and present wishes, consult appropriate people and choose the less restrictive effective option. For serious medical treatment when an unbefriended person in England or Wales has no appropriate consultee, an Independent Mental Capacity Advocate may be required. Major unresolved conflict or exceptional treatment questions may need Court of Protection review.
The devolved frameworks are not interchangeable. Scotland's Adults with Incapacity legislation uses benefit, least-restrictive intervention, wishes and consultation principles and distinct welfare-attorney and medical-treatment provisions. Northern Ireland's 2016 mental-capacity legislation has been commenced in phases alongside local arrangements. In cross-border, contested or life-sustaining cases, obtain jurisdiction-specific advice rather than translating MCA forms by analogy.