Informed consent is a term used in the medical field to describe the process of obtaining permission before performing any healthcare intervention on an individual. Informed consent can be said to have been given when the person demonstrates a clear appreciation and understanding of the situation, regardless of whether that person can speak.
However, in order to give informed consent, a patient must have sufficient reasoning facilities and be in possession of all relevant facts. Certain states are said to preclude informed consent, including Alzheimer's disease, being in a coma, intellectual disability, intoxication, or severe mental illness. Often, when an individual is unable to provide informed consent, there is usually a designated person authorized to provide the consent, such as parents, guardians, or conservators of the mentally ill.
In order to give informed consent, there must be three components present. First, investigators must ensure that the patient has adequate comprehension of the provided information. Second, the patient must both understand the information and be able to form a reasonable judgment of the potential consequences of that decision. Third, this decision must be voluntary; that is, freely given without coercion, manipulation, or undue influence. However, there is always some degree of assumption of informed consent based upon the observation of the questioner.