For consent to be valid, it must be given voluntarily by an appropriately informed person who has the capacity to consent to the intervention in question (this will be the patient or, for a patient under the age of 18, a person with parental responsibility for the patient, a person authorized to give consent, or a person appointed by the court to make treatment decisions.

Agreement where the person does not know what the intervention entails is not "consent."

See reference for more information.

Reference guide to consent for examination or treatment. 2nd ed. NHS (National Health Service) Department of Health, July 2009. Internet. Accessed on December 27, 2016.