“1 The principles (5) 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) Before the act is done, or the decision is made, regard must be had to whether the purpose for which it is needed can be as effectively achieved in a way that is less restrictive of the person's rights and freedom of action. 4 Best interests (1) In determining for the purposes of this Act what is in a person's best interests, the person making the determination 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. (2) The person making the determination must consider all the relevant circumstances and, in particular, take the following steps. (3) He must consider– (a) whether it is likely that the person will at some time have capacity in relation to the matter in question, and (b) if it appears likely that he will, when that is likely to be. (4) He 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. … (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) He must 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 … as to what would be in the person's best interests and, in particular, as to the matters mentioned in subsection (6). … (10) “Life-sustaining treatment” means treatment which in the view of a person providing health care for the person concerned is necessary to sustain life. (11) "Relevant circumstances" are those— (a) of which the person making the determination is aware, and (b) which it would be reasonable to regard as relevant.”
“I venture, however, to add the following observations: (i) First, P's wishes and feelings will always be a significant factor to which the court must pay close regard: see Re MM; Local Authority X v MM (by the Official Solicitor) and KM[2007] EWHC 2003 (Fam) ,[2009] 1 FLR 443 , at paras [121]-[124]. (ii) Secondly, the weight to be attached to P's wishes and feelings will always be case-specific and fact-specific. In some cases, in some situations, they may carry much, even, on occasions, preponderant, weight. In other cases, in other situations, and even where the circumstances may have some superficial similarity, they may carry very little weight. One cannot, as it were, attribute any particular a priori weight or importance to P's wishes and feelings; it all depends, it must depend, upon the individual circumstances of the particular case. And even if one is dealing with a particular individual, the weight to be attached to their wishes and feelings must depend upon the particular context; in relation to one topic P's wishes and feelings may carry great weight whilst at the same time carrying much less weight in relation to another topic. Just as the test of incapacity under the 2005 Act is, as under the common law, 'issue specific', so in a similar way the weight to be attached to P's wishes and feelings will likewise be issue specific. (iii) Thirdly, in considering the weight and importance to be attached to P's wishes and feelings the court must of course, and as required by section 4(2) of the 2005 Act, have regard to all the relevant circumstances. In this context the relevant circumstances will include, though I emphasise that they are by no means limited to, such matters as: a) the degree of P's incapacity, for the nearer to the borderline the more weight must in principle be attached to P's wishes and feelings: Re MM; Local Authority X v MM (by the Official Solicitor) and KM at para [124]; b) the strength and consistency of the views being expressed by P; c) the possible impact on P of knowledge that her wishes and feelings are not being given effect to: see again Re MM; Local Authority X v MM (by the Official Solicitor) and KM, at para [124]; d) the extent to which P's 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 P's wishes and feelings, if given effect to, can properly be accommodated within the court's overall assessment of what is in her best interests”