The legal principles apply to withdrawing and withholding life-prolonging treatment as apply to any other medical intervention. The gravity and sensitivity of decisions concerning life-prolonging treatment are that the assessment of capacity and of best interests are particularly important. A competent adult therefore has the right to consent to or refuse treatment even where refusal may result in harm to themselves or in their own death. Where adults lack capacity to decide for themselves about life-prolonging treatment, health professionals must apply the Mental Capacity Act 2005. The use of artificial nutrition and hydration constitutes medical treatment. Decisions about the proposed withholding or withdrawal of artificial nutrition and hydration from a patient in a permanent vegetative state should be referred to court. The decision to withdraw or withhold life-sustaining treatment must be made in the best interests of the child. A person with parental responsibility for a child or young person can consent to treatment on their behalf.