(1) For the purposes of this Act, a person lacks capacity in relation to a matter if at the material time he is unable to make a decision for himself in relation to the matter because of an impairment of, or a disturbance in the functioning of, the mind or brain.

(2) It does not matter whether the impairment or disturbance is permanent or temporary.

(3) A lack of capacity cannot be established merely by reference to--
(a) a person's age or appearance, or
(b) a condition of his, or an aspect of his behaviour, which might lead others to make unjustified assumptions about his capacity.

Mental capacity is the ability to make a decision.
- This includes the ability to make a decision that affects daily life such as when to get up, what to wear or whether to go to the doctor when feeling ill - as well as more serious or significant decisions.
- It also refers to a person's ability to make a decision that may have legal consequences - for them or others. Examples include agreeing to have medical treatment, buying goods or making a will.

Detailing, for each enquiry, whether the adult at risk lacked capacity to make decisions related to the safeguarding enquiry.

The ability of a person to make a decision about their own care, including:

- decisions that affect daily life (for example, when to get up, what to wear or whether to go to the doctor when feeling ill, and more serious or significant decisions)
- decisions that may have legal consequences for them or others (for example, agreeing to have medical treatment, buying goods or making a will).

The Mental Capacity Act 2005 defines a lack of mental capacity as when 'a person lacks capacity in relation to a matter if at the material time he is unable to make a decision for himself in relation to the matter because of an impairment of, or a disturbance in the functioning of, the mind or brain'. Health professionals should follow the Department of Health's advice on consent. If a person does not have capacity to make decisions, health and social care practitioners should follow the code of practice that accompanies the Mental Capacity Act and the supplementary code of practice on deprivation of liberty safeguards.

Capacity is routinely used by professionals to refer to "mental capacity". This will not always be clear to care recipients and their friends/family: care needs to be taken to explain this meaning.

A person's mental capacity may fluctuate over time and may vary depending on the decision to be made. This isn't always understood or recognised by health professionals, although the definitions here are reasonably consistent about it. This can lead to people being inappropriately prevented from making decisions which they do have the capacity to make.

Many of the definitions here don't place enough emphasis on the non-binary nature of capacity ("at the material time" and "in relation to the matter").