“An adult person of sound mind is entitled to decide which, if any, of the available forms of treatment to undergo, and her consent must be obtained before treatment interfering with her bodily integrity is undertaken. The doctor is therefore under a duty to take reasonable care to ensure that the patient is aware of any material risks involved in any recommended treatment, and of any reasonable alternative or variant treatments. The test of materiality is whether, in the circumstances of the particular case, a reasonable person in the patient’s position would be likely to attach significance to the risk, or the doctor is or should reasonably be aware that the particular patient would be likely to attach significance to it”.
A Comment in the [Australian] High Court’s decision in Rogers v Whitaker (1992) 175 CLR 479.
This judgement and form of words was repeated in the UK Supreme Court decision in Montgomery -v- Lanarkshire Health Board 2015.