Synopsis
Assess whether a person can make one defined decision at the required time after all practicable support, apply the correct jurisdiction's legal test, and distinguish incapacity from diagnosis, detention, communication difficulty or an unwise choice.
- Define the exact decision, available options, material benefits and harms, consequences of no action and the time by which it must be made.
- Presume capacity and take all practicable steps to support the decision through timing, treatment of reversible factors, interpreter, sensory aids, simple language and communication technology.
- In England and Wales, identify an impairment or disturbance of mind or brain and ask whether, because of it, the person cannot understand, retain, use or weigh, or communicate relevant information.
- Short retention can be enough; communication can use speech, sign, writing, gesture, eye gaze or assistive technology.
- Ask the person to explain choices, consequences and reasoning in their own words; record actual responses rather than a conclusory capacity present or absent statement.
- An unwise, risky or values-based choice can be capacitous. The test concerns the decision process, not agreement with professional advice.
- If capacity fluctuates and the decision can safely wait, reassess at the person's optimal time; urgent harm may require a proportionate temporary decision process.
- If capacity is absent, check valid advance refusals, health-and-welfare attorney or deputy powers, court orders and the correct best-interests or jurisdiction-specific pathway.
- Mental-health detention does not itself remove capacity, and ordinary physical treatment unrelated to mental disorder still needs its own consent or capacity authority.
Key red flags
Age, diagnosis, psychosis, detention, intoxication, learning disability, communication impairment or an apparently irrational outcome cannot alone establish lack of capacity.
In England and Wales, inability must result from an impairment or disturbance in functioning of mind or brain; functional difficulty without the causal link does not complete the statutory test.
A person may lack capacity for one complex treatment decision while retaining capacity for another choice, and capacity may recover after delirium, intoxication or acute distress improves.
Failure to provide interpreter, hearing aids, accessible information, pain relief, time or a suitable communication method can create a false incapacity conclusion.
Capacity law is not identical across the UK: do not transpose Mental Capacity Act forms or terminology into Scotland or Northern Ireland without current local verification.
Investigation priorities
Specify the actual options, benefits, harms, no-action consequence and decision deadline.
Management branches
There is a genuine reason to doubt ability for a specific healthcare or welfare choice.
- Define the decision, material information and urgency and identify the applicable UK jurisdiction and possible impairment.
- Provide practicable communication and clinical support, then ask the person to explain and compare options and communicate a choice.
- Record each functional ability, causal reasoning where required, actual responses, support, conclusion and when reassessment is needed.