asked Her Majesty's Government:
What is their policy on the withdrawal or withholding of nutrition and hydration delivered by artificial means from mentally incapacitated patients.
An adult with capacity is able to refuse any form of medical treatment including artificial nutrition and hydration (except in circumstances defined by statute, for example the Mental Health Act 1983). Where the patient is incapacitated and has not made a relevant advance refusal, treatment will be lawful if it is in their best interests. Hence, if the treatment is not in the best interests of the patient it may lawfully be discontinued.
Procedural safeguards can be found in professional guidelines, including the General Medical Council's guidance document, Withholding and Withdrawing Life-Prolonging Treatments: Good Practice in Decision Making (http://www.gmc-uk.org/standards/default.htm). Copies are available in the Library. In cases of difficulty, doubt or disagreement, the matter can be referred to the court for adjudication.