Best Interests

The Mental Capacity Act 2005 rules out shortcuts. Section 4 provides that in working out what is in a person's best interests, the decision-maker 'must not make it merely on the basis of — (a) the 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 what might be in his best interests.' Instead, the decision-maker 'must consider all the relevant circumstances' and take a defined set of steps.

Those steps put the person's own voice at the centre of the decision as far as possible. The decision-maker must, 'so far as reasonably practicable, permit and encourage the person to participate, or to improve his ability to participate, as fully as possible in any act done for him and any decision affecting him', and must consider, 'so far as is reasonably ascertainable — (a) the person's past and present wishes and feelings ... (b) the beliefs and values that would be likely to influence his decision if he had capacity, and (c) the other factors that he would be likely to consider if he were able to do so.' Where the decision concerns life-sustaining treatment, the Act adds a specific safeguard: the decision-maker 'must not, in considering whether the treatment is in the best interests of the person concerned, be motivated by a desire to bring about his death.' The same phrase does separate work in children's healthcare decisions: NHS guidance on consent notes that if a parent refuses a particular treatment for their child, 'this decision can be overruled by the courts if treatment is thought to be in the best interests of the child' — the same welfare-first test, applied outside the Mental Capacity Act.