01Purpose and principlesWhat the treatment does and how it fits into care.
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.
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.
Key points
- Presume capacity and assess the actual decision at the time it must be made, not the person's diagnosis or global cognitive status.
- First-line practice is supported decision making: optimise pain, oxygenation and attention, treat delirium, use hearing aids, interpreter, simple language, visual material and sufficient time.
- In England and Wales, ask whether an impairment or disturbance affects mind or brain and whether it causes inability to understand, retain, use or weigh, or communicate the decision.
- Short retention can be enough; communication may use speech, sign, writing, gesture or assistive technology.
- An unwise decision is not incapacity. Test the reasoning process and grasp of consequences rather than whether the clinician agrees with the outcome.
- If capacity is absent, first check for a valid applicable advance refusal, health-and-welfare attorney, deputy or relevant court order.
- Best interests considers current and past wishes, values, beliefs, consultation, chance of regaining capacity and all relevant circumstances; it is not a family vote or pure medical convenience.
- The gold-standard record connects the impairment, functional evidence, support attempted, legal authority, options, consultation, reasoning and least restrictive outcome.
- England and Wales use the Mental Capacity Act 2005; Scotland uses the Adults with Incapacity (Scotland) Act 2000, and Northern Ireland requires attention to the 2016 Act's current commencement and local framework.
02Indications, selection and cautionsWho may benefit, who needs urgent treatment and important alternatives.
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.
03Assessment before treatmentTests and checks that guide safe selection.
Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.
- 01
First-line decision definitionFirst stepFirst line - Why
- State the exact choice, options, material benefits, burdens, consequences of no action and time by which a decision is required.
- Interpretation and limitations
- A vague assessment of 'general capacity' is invalid; complexity and information should be proportionate to the actual choice.
- 02
Impairment or disturbance assessment - Why
- Identify delirium, dementia, brain injury, mental illness, intoxication or another dysfunction capable of affecting decision making.
- Interpretation and limitations
- Presence of a diagnosis is not enough; under the England-and-Wales test, connect it causally to the demonstrated functional inability.
- 03
Four-ability functional interview - Why
- Test understanding, retention, use or weighing and communication after information is presented accessibly.
- Interpretation and limitations
- Record the person's responses and reasoning rather than a conclusory label; inability in any required domain may establish lack of capacity when caused by impairment.
- 04
Reversible-factor and support review - Why
- Assess pain, hypoxia, infection, metabolic disturbance, medicines, fatigue, environment, language, hearing and communication method.
- Interpretation and limitations
- Correcting a barrier may restore decision ability; failure to attempt practicable support undermines the assessment.
- 05
Legal authority search - Why
- Check advance refusal, LPA registration and scope, deputy order, court direction and any jurisdiction-specific welfare proxy.
- Interpretation and limitations
- Authority is decision and time limited; verify life-sustaining powers and do not substitute a finance attorney or informal relative.
- 06
Best-interests evidence map - Why
- Gather current wishes, prior statements, values, beliefs, family and professional evidence, available options, likely outcomes and chance of recovery.
- Interpretation and limitations
- The conclusion should explain why one option best respects the whole person and is the least restrictive effective choice, including dissent.
04Treatment approachPreparation, options, escalation and aftercare.
01Capacity assessmentSupport first, then test the decisionFirst stepThere is a reasonable concern that the patient may not be able to make a specific healthcare decision.+
- 1Define the decision and urgency, identify potential impairment and correct reversible clinical or communication barriers as far as practicable.
- 2Explain material information accessibly and assess understanding, retention, use or weighing and communication, recording the person's actual responses.
- 3If capacity is present, respect the choice; if absent, state the causal reasoning, consider safe delay and identify the lawful next decision process.
02Best interestsChoose through evidence, values and proportionalityThe patient lacks capacity and no valid applicable refusal directly determines the treatment decision.+
- 1Check attorney, deputy and court authority, involve the person as far as possible and collect past and present wishes, values and views from appropriate consultees.
- 2Compare each clinically available option, including no treatment and delayed treatment, for benefit, burden, reversibility and effect on rights and relationships.
- 3EscalationSelect and document the least restrictive option that best serves the person overall, state dissent and arrange review or legal escalation when required.
03Advance refusalTest validity and applicability preciselyA person lacking capacity may have previously refused the treatment now proposed.+
- 1Obtain the original or reliable copy and verify identity, capacity at creation where disputed, absence of withdrawal and any later inconsistent act or proxy appointment.
- 2Match the named treatment and circumstances to the current case and confirm written, signed, witnessed and life-risk wording for England-and-Wales life-sustaining refusal.
- 3Follow the refusal when valid and applicable; if genuine doubt remains, provide only necessary holding care and seek urgent senior or court advice rather than asking family to override it.
04Fluctuation or disputePreserve autonomy and secure reviewCapacity may return or clinicians, proxy and family disagree about authority or best interests.+
- 1Decide whether treatment can safely wait, repeat assessment at an optimal time and use specialist communication, psychiatric, neurological or advocacy support as relevant.
- 2Clarify legal roles, share evidence transparently, hold a best-interests meeting and seek a second clinical opinion or mediation.
- 3Apply statutory safeguards for restraint or liberty restriction and obtain urgent legal or court review for unresolved serious treatment conflict.
05Complications, monitoring and follow-upAdverse effects, response and longer-term review.
- Reassess capacity when the decision, information, impairment or timing changes; do not copy a previous conclusion into a new choice.
- Track and treat delirium, pain, hypoxia, infection, retention, constipation and medicine effects that may alter ability.
- Review best-interests decisions when capacity returns, prognosis changes, a less restrictive option appears or new evidence of wishes emerges.
- Confirm that attorneys and deputies remain authorised for the particular matter and that the correct registered instrument is available.
- Document restraint duration, proportionality and review, and activate deprivation-of-liberty or court safeguards where applicable.
- Audit whether interpreter, advocate and communication support are used equitably for people with disability or limited English.
06Special situationsVariants, exceptions and circumstances that change the usual approach.
Capacity is an ability
The assessment asks whether the person can make this choice, not whether the clinician regards the eventual choice as prudent.
Executive function matters
A person may repeat facts yet be unable to compare or apply consequences because frontal or psychiatric dysfunction impairs weighing.
Brief retention may suffice
The law does not demand long-term recall if the person can hold information long enough to use it for the decision.
Best interests is not substitution
Past preferences are central evidence but the decision also considers current experience, clinical options, relationships, rights and foreseeable consequences.
Serious disputes need process
Time pressure should prompt early senior and legal escalation, not a contest between clinician authority and family insistence at the bedside.
07Common pitfallsFrequent interpretation and management errors.
- 01
Using a cognitive score as the capacity decision.
- 02
Testing capacity before providing hearing, language or communication support.
- 03
Finding incapacity because the patient chooses a risky option.
- 04
Writing that capacity is absent without identifying the functional evidence and causal impairment.
- 05
Asking next of kin to consent despite no relevant legal authority.
- 06
Treating an advance statement as identical to a binding advance refusal.
- 07
Ignoring the extra formalities for refusing life-sustaining treatment in England and Wales.
- 08
Applying England-and-Wales procedures in Scotland or Northern Ireland without local verification.
- 09
Using restraint or covert administration without necessity, proportionality and the relevant safeguards.
- 10
Delaying legal advice until an entrenched dispute reaches the point of emergency.