This is an explanation of "Informed Consent" which is a patient's Common Law and Constitutional right in South Africa:
Informed consent by a patient is required for any treatment a doctor considers advisable, either for purposes of diagnosis or treatment, except in exceptional cases, such as unconscious accident cases. Patients who have executed the Living Will have, in their right minds, given definite instructions regarding the type of treatment to which they will not consent when dying, thereby exercising their legal prerogative to lay down limits to what may be done to them. This is binding in law, and a doctor who disregards this instruction by a patient, is legally in the wrong.
No matter how sincerely the doctor may believe himself/herself to be acting in the patient's best interests, or according to moral principles, if a patient does not consent to treatment, then, with certain exceptions of which the Living Will is not one, the doctor's act is unlawful, and may render him/her liable to damages. It should be noted that in South African law it is the patient's informed consent, not the doctor's motive, which makes the latter's act lawful.
Professor David McQuoid-Mason, of Natal University Faculty of Law, outlined the patient's legal right and the problem a doctor may face if he/she disregards the Living Will. "It is the duty of medical personnel to obey a patient's wishes if he/she does not want life-sustaining treatment and has signed a Living Will (which must obviously be brought to the doctor's attention). If a doctor then does not obey the patient's wishes he/she has in fact perpetrated an assault against the patient and can be sued".
Professor McQuoid-Mason said the law recognised the patient's right to decide whether he/she wanted to live or die, accept treatment or refuse it.