Adult Social Care Glossary, v 0.6

(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.