"An act done, or decision made, under this Act for or on behalf of a person who lacks capacity must be done, or made, in his best interests." "
"(6) He must consider, so far as is reasonably ascertainable – (a) the person's past and present wishes and feelings (and, in particular, any relevant written statement made by him when he had capacity), (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." (7) I must also take into account, if it is practicable and appropriate to consult them, the views of – (a) anyone named by the person as someone to be consulted on the matter in question or on matters of that kind, (b) anyone engaged in caring for the person or interested in his welfare, (c) any donee of a lasting power of attorney granted by the person, and (d) any deputy appointed for the person by the court, as to what would be in the person's best interests and, in particular, as to the matters mentioned in subsection (6)."
"The courts have considered how s4 is to be applied in a number of reported cases. There is consensus that, as matters stand, the following should be borne in mind: i) The decision must be made in DE's best interests not, in the interests of others although the interests of others may indirectly be a factor insofar as they relate to [his] best interests. ii) The court is not tied to any clinical assessment of what is in DE's best interests and should reach its own conclusion on the evidence before it. iii) Best Interests is an objective test. iv) The weight to be attached to the various factors will, inevitably, differ depending upon the individual circumstances of the particular case. A feature or factor which in one case may carry great, possibly even preponderant, weight may in another, superficially similar case, carry much less, or even very little, weight. v) There is no hierarchy in the list of factors in s4 and the weight to be attached to the various factors will depend upon the individual circumstances. vi) There may, in the particular case, be one or more features or factors which, as Thorpe LJ has frequently put it, are of "magnetic importance" in influencing or even determining the outcome. viii) The declaration should not be sought if… disproportionate and not the least restrictive step. Risk management is better than invasive treatment. ix) The decision is for the Judge not the expert. Their roles are distinct and it is for the Judge to make the final decision…"
"… the weight to be attached to their wishes and feelings must depend upon the particular context…"
"… the degree of [the patient's] incapacity, for the nearer to the borderline the more weight must in principle be attached to [his] wishes and feelings… b) the strength and consistency of the views being expressed by [him]; c) the possible impact on [him] of knowledge that [his] wishes and feelings are not being given effect to... d) the extent to which [his] wishes and feelings are, or are not, rational, sensible, responsible and pragmatically capable of sensible implementation in the particular circumstances; and e) crucially, the extent to which [his] wishes and feelings, if given effect to, can properly be accommodated within the court's overall assessment of what is in [his] best interests."