With thanks to Dr W Jammal for pointing out that the UK Supreme Court has now reviewed the Court of Appeal decision in the matter of Aintree University Hospitals v James. The ultimate decision is reported as Aintree University Hospitals v James  UKSC 67.
The following extract is from the media summary published by the Court:
A patient cannot order a doctor to give a particular form of treatment (although he may refuse it) and the court’s position is no different . However, any treatment which doctors do decide to give must be lawful. Generally it is the patient’s consent which makes invasive medical treatment lawful . If a patient is unable to consent it is lawful to give treatment which is in his best interests . The fundamental question is whether it is in the patient’s best interests, and therefore lawful, to give the treatment, not whether it is lawful to withhold it .
The starting point is the strong presumption that it is in a person’s best interests to stay alive . In considering the best interests of a particular patient at a particular time, decision-makers must look at his welfare in the widest sense, not just medical but social and psychological; they must consider the nature of the medical treatment in question, what it involves and its prospects of success; they must consider what the outcome of that treatment for the patient is likely to be; they must try and put themselves in the place of the individual patient and ask what his attitude is or would be likely to be; and they must consult others who are looking after him or interested in his welfare . The judge was right to consider whether the proposed treatments would be futile in the sense of being ineffective or being of no benefit to the patient. He was right to weigh the burdens of treatment against the benefits of a continued existence, and give great weight to Mr James’ family life, which was “of the closest and most meaningful kind” . He was right to be cautious in circumstances which were fluctuating . A treatment may bring some benefit to a patient even if it has no effect upon the underlying disease or disability . It was not futile if it enabled a patient to resume a quality of life which the patient would regard as worthwhile .
The Court of Appeal had been wrong to reject the judge’s approach. It had also been wrong to suggest that the test of the patient’s wishes and feelings was an objective one, namely what the reasonable patient would think. Insofar as it was possible to ascertain the patient’s wishes and feelings, his beliefs and values or the things which were important to him, these should be taken into account because they were a component in making the choice which was right for him as an individual human being . However, by the time of the appeal there had been such a significant deterioration in Mr James’ condition that the time had indeed come when it was no longer in his best interests to provide the treatments. The prospect of his regaining even his previous quality of life was by then very slim. The Court of Appeal had therefore been correct to allow Aintree’s appeal .