Informed consent is a process for getting permission before conducting a healthcare intervention on a person. A health care provider may ask a patient to consent to receive therapy before providing it, or a clinical researcher may ask a research participant before enrolling that person into a clinical trial. Informed consent is collected according to guidelines from the fields of medical ethics and research ethics.
An informed consent can be said to have been given based upon a clear appreciation and understanding of the facts, implications, and future consequences of an action. In order to give informed consent, the individual concerned must have adequate reasoning faculties and be in possession of all relevant facts at the time consent is given. Impairments to reasoning and judgment which may make it impossible for someone to give informed consent include such factors as basic intellectual or emotional immaturity, high levels of stress such as PTSD or as severe mental retardation, severe mental illness, intoxication, severe sleep deprivation, Alzheimer's disease, or being in a coma. This term was first used in a 1957 medical malpractice case by Paul G. Gebhard.
Some acts can take place because of a lack of informed consent. In cases where an individual is considered unable to give informed consent, another person is generally authorized to give consent on his behalf, e.g., parents or legal guardians of a child (though in this circumstance the child may be required to provide informed assent) and conservators for the mentally ill.
In cases where an individual is provided insufficient information to form a reasoned decision, serious ethical issues arise. Such cases in a clinical trial in medical research are anticipated and prevented by an ethics committee or Institutional Review Board.
Assessment of consent 
Informed consent can be complex to evaluate, because neither expressions of consent, nor expressions of understanding of implications, necessarily mean that full adult consent was in fact given, nor that full comprehension of relevant issues is internally digested. Consent may be implied within the usual subtleties of human communication, rather than explicitly negotiated verbally or in writing. In some cases consent cannot legally be possible, even if the person protests he does indeed understand and wish. There are also structured instruments for evaluating capacity to give informed consent, although no ideal instrument presently exists.
There is thus always a degree to which informed consent must be assumed or inferred based upon observation, or knowledge, or legal reliance. This especially is the case in sexual or relational issues. In medical or formal circumstances explicit agreement by means of signature which may normally be relied upon legally, regardless of actual consent, is the norm. This is the case with certain procedures, such as a "do not resuscitate" directive signed by a patient prior to their illness.
Brief examples of each of the above:
- A person may verbally agree to something from fear, perceived social pressure, or psychological difficulty in asserting his true feelings. The person requesting the action may honestly be unaware of this and believe the consent is genuine, and rely upon it. Consent is expressed, but not internally given.
- A person may state he understands the implications of some action, as part of his consent, but in fact has failed to appreciate the possible consequences fully and later deny the validity of his consent for this reason. Understanding needed for informed consent is stated to be present but is in fact (through ignorance) not present.
- A person may move from friendship to sexual contact on the basis of body language and apparent receptivity, but very few people on a date that results in sexual contact have explicitly asked the other if his or her consent is informed, if he does in fact fully understand what is implied, and all potential conditions or results. Informed consent is implied (or assumed unless disproved) but not stated explicitly.
- A person below the age of consent may agree to sex, knowing all the consequences, but his or her consent is deemed invalid as he is deemed to be a child unaware of the issues and thus incapable of being informed consent. Individual is barred from legally giving informed consent, despite what they may feel (1)
- In some countries (notably the United Kingdom), individuals may not consent to injuries being inflicted upon them, and so a person practicing sadism and masochism upon a consenting partner may be deemed to have caused actual bodily harm without consent, actual consent notwithstanding. Individual is barred from legally giving informed consent, despite what they may feel (2). See also Spanner case and 'consensual non-consensuality'.
- A person signs a legal release form for a medical procedure, and later feels he did not really consent. Unless he can show actual misinformation, the release is usually persuasive or conclusive in law, in that the clinician may rely legally upon it for consent. In formal circumstances, a written consent will usually legally override later denial of informed consent (unless obtained by misrepresentation)
- A person or institution (e.g., a school or childcare professional) exposes a minor to non-age-appropriate material, in any media format, without the expressed informed consent of the minor's parent or legal guardian. Informed consent in this instance goes to the argument of competency on the part of the minor. An example would be the showing of an R rated movie to a 12-year-old by an educational institution without the informed consent of the parent or legal guardian.
- Informed consent in the U.S. can be overridden in emergency medical situations pursuant to 21CFR50.24, which was first brought to the general public's attention via the controversy surrounding the study of Polyheme.
Elements of valid informed consent 
- While Disclosure requires the researcher to supply the subject with the information necessary to make an autonomous decision, the investigators must ensure that subjects have adequate comprehension of the information provided. This latter requirement implies that the consent form be written in lay language suited for the apprehension skills of subject population, as well as assessing the level of understanding during the meeting.
- Capacity pertains to the ability of the subject to both understand the information provided and form a reasonable judgment based on the potential consequences of his/her decision.
- Voluntariness refers to the subject’s right to freely exercise his/her decision making without being subjected to external pressure such as coercion, manipulation, or undue influence.
Waiver of informed consent requirement 
Waiver of the consent requirement may be applied in certain circumstances where no foreseeable harm is expected to result from the study or when permitted by law, federal regulations, or if an ethical review committee has approved the non-disclosure of certain information.
Besides studies with minimal risk, waivers of consent may be obtained in a military setting. According to 10 USC 980, the United States Code for the Armed Forces, Limitations on the Use of Humans as Experimental Subjects, a waiver of advanced informed consent may be granted by the Secretary of Defense if a research project would:
- Directly benefit subjects.
- Advance the development of a medical product necessary to the military.
- Be carried out under all laws and regulations (i.e., Emergency Research Consent Waiver) including those pertinent to the FDA.
"Informed consent" is a technical term with a modern meaning. In tracing its history, some scholars have suggested tracing the history of checking for any of these practices::54
- a patient agrees to a health intervention based on an understanding of it
- the patient has multiple choices and is not compelled to choose a particular one
- the consent includes giving permission
These practices are all part of what constitutes informed consent and their history is the history of informed consent.:60 They combined to form the modern concept of informed consent rose in response to particular problems which happened in modern research.:60 Whereas various cultures in various places practiced informed consent, the modern concept of informed consent was developed by people who drew influence from Western tradition.:60
Medical history 
Historians cite a series of medical guidelines to trace the history of informed consent in medical practice.
The Hippocratic Oath, a 500 B.C.E. Greek text, was the first set of Western writings giving guidelines for the conduct of medical professionals. It advises that physicians should conceal most information from patients in order to give the patients the best care.:61 The rationale is a beneficence model for care; the doctor knows better than the patient and therefore should direct the patient's care because the patient is not likely to have ideas which would be better than the doctor's.:61
Henri de Mondeville was a French surgeon who in the 1300s wrote about medical practice. He traced his ideas to the Hippocratic Oath.:63 Among his recommendations were that doctors "promise a cure to every patient" in hopes that the good prognosis would inspire a good outcome to treatment.:63 Mondeville never mentioned getting consent, but did emphasize the need for the patient to have confidence in the doctor.:63 He also advised that when deciding therapeutically unimportant details the doctor should meet the patients' requests "so far as they do not interfere with treatment".
Benjamin Rush was an 18th century United States physician who was influenced by the Age of Enlightenment cultural movement.:65 Because of this, he advised that doctors ought to share as much information as possible with patients. He recommended that doctors educate the public and respect a patient's informed decision to accept therapy.:65 There is no evidence that he supported seeking a consent from patients.:65 In a lecture titled "On the duties of patients to their physicians", he stated that patients should be strictly obedient to the physician's orders; this was representative of much of his writings.:65 John Gregory, Rush's teacher, wrote similar views that a doctor could best practice beneficence by making decisions for the patients without their consent.:66
Thomas Percival was a British physician who published a book called Medical Ethics in 1803.:68 Percival was a student of the works of Gregory and various earlier Hippocratic physicians.:68 Like all previous works, Percival's Medical Ethics makes no mention of soliciting for the consent of patients or respecting their decisions.:68 Percival said that patients have a right to truth, but when the physician could provide better treatment by lying or withholding information, he advised that the physician do as he thought best.:68
When the American Medical Association was founded they in 1847 produced a work called the first edition of the American Medical Association Code of Medical Ethics.:69 Many sections of this book are verbatim copies of passages from Percival's Medical Ethics.:69 A new concept in this book was the idea that physicians should fully disclose all patient details truthfully when talking to other physicians, but the text does not also apply this idea to disclosing information to patients.:70 Through this text, Percival's ideas became pervasive guidelines throughout the United States as other texts were derived from them.:70
Worthington Hooker was an American physician who in 1849 published Physician and Patient.:70 This medical ethics book was radical demonstrating understanding of the AMA's guidelines and Percival's philosophy and soundly rejecting all directives that a doctor should lie to patients.:70 In Hooker's view, benevolent deception is not fair to the patient, and he lectured widely on this topic.:70 Hooker's ideas were not broadly influential.:70
Research history 
Historians cite a series of Human subject research experiments to trace the history of informed consent in research.
Tearoom Trade is the name of a book by American psychologist Laud Humphreys. In it he describes his research into male homosexual acts. In conducting this research he never sought consent from his research subjects and other researchers raised concerns that he violated the right to privacy for research participants.
The Milgram experiment is the name of a 1961 experiment conducted by American psychologist Stanley Milgram. In the experiment Milgram had an authority figure order research participants to commit a disturbing act of harming another person. After the experiment he would reveal that he had deceived the participants and that they had not hurt anyone, but the research participants were upset at the experience of having participated in the research. The experiment raised broad discussion on the ethics of recruiting participants for research without giving them full information about the nature of the research.
Medical procedures 
The doctrine of informed consent relates to professional negligence and establishes a breach of the duty of care owed to the patient (see duty of care, breach of the duty, and respect for persons). The doctrine of informed consent also has significant implications for medical trials of medications, devices, or procedures.
Requirements of the professional 
In the United Kingdom and countries such as Malaysia and Singapore, informed consent in medical procedures requires proof as to the standard of care to be expected as a recognised standard of acceptable professional practice (the Bolam Test), that is, what risks would a medical professional usually disclose in the circumstances (see Loss of right in English law). Arguably, this is "sufficient consent" rather than "informed consent."
In the United States, Australia, and Canada, a more patient-centered approach is taken and this approach is usually what is meant by the phrase "informed consent." Informed consent in these jurisdictions requires that significant risks be disclosed, as well as risks which would be of particular importance to that patient. This approach combines an objective (the reasonable patient) and subjective (this particular patient) approach.
The doctrine of informed consent should be contrasted with the general doctrine of medical consent, which applies to assault or battery. The consent standard here is only that the person understands, in general terms, the nature of and purpose of the intended intervention. As the higher standard of informed consent applies to negligence, not battery, the other elements of negligence must be made out. Significantly, causation must be shown: That had the individual been made aware of the risk he would not have proceeded with the operation (or perhaps with that surgeon).
Optimal establishment of an informed consent requires adaptation to cultural or other individual factors of the patient. For example, people from Mediterranean and Arab appear to rely more on the context of the delivery of the information, with the information being carried more by who is saying it and where, when, and how it's being said, rather than what is said, which is of relatively more importance in typical "Western" countries.
The informed consent doctrine is generally implemented through good healthcare practice: pre-operation discussions with patients and the use of medical consent forms in hospitals. However, reliance on a signed form should not undermine the basis of the doctrine in giving the patient an opportunity to weigh and respond to the risk. In one British case, a doctor performing routine surgery on a woman noticed that she had cancerous tissue in her womb. He took the initiative to remove the woman's womb; however, as she had not given informed consent for this operation, the doctor was judged by the General Medical Council to have acted negligently. The council stated that the woman should have been informed of her condition, and allowed to make her own decision.
Obtaining informed consents 
To capture and manage informed consents, hospital management systems typically use paper-based consent forms which are scanned and stored in a document handling system after obtaining the necessary signatures. Hospital systems and research organizations are adopting an electronic way of capturing informed consents to enable indexing, to improve comprehension, search and retrieval of consent data, thus enhancing the ability to honor to patient intent and identify willing research participants.
Competency of the patient 
The ability to give informed consent will be governed by a general requirement of competency. In common law jurisdictions, adults are presumed competent to consent. This presumption can be rebutted, for instance, in circumstances of mental illness or other incompetence. This may be prescribed in legislation or based on a common-law standard of inability to understand the nature of the procedure. In cases of incompetent adults, a health care proxy makes medical decisions. In the absence of a proxy, the medical practitioner is expected to act in the patient's best interests until a proxy can be found.
By contrast, 'minors' (which may be defined differently in different jurisdictions) are generally presumed incompetent to consent, but depending on their age and other factors may be required to provide Informed assent. In some jurisdictions (e.g. much of the U.S.), this is a strict standard. In other jurisdictions (e.g. England, Australia, Canada), this presumption may be rebutted through proof that the minor is ‘mature’ (the ‘Gillick standard’). In cases of incompetent minors, informed consent is usually required from the parent (rather than the 'best interests standard') although a parens patriae order may apply, allowing the court to dispense with parental consent in cases of refusal.
Research involving deception is controversial given the requirement for informed consent. Deception typically arises in social psychology, when researching a particular psychological process requires that investigators deceive subjects. For example, in the Milgram experiment, researchers wanted to determine the willingness of participants to obey authority figures despite their personal conscientious objections. They had authority figures demand that participants deliver what they thought was an electric shock to another researcher. For the study to be successful, it was necessary to deceive the participants so they believed that the subject was a peer and that their electric shocks caused the peer actual pain.
Nonetheless, research involving deception prevents the subject/patient from exercising his/her basic right of autonomous informed decision-making and conflicts with the ethical principle of Respect for persons.
It is stated in the Ethical Principles of Psychologists and Code of Conduct set by the American Psychological Association, that psychologists may not conduct research that includes a deceptive compartment unless the act is justified by the value and the importance of the results of such study, provided that this could not be obtained in an alternative way. Moreover, the research should bear no potential harm to the subject as an outcome of deception, be it physical pain or emotional distress. Finally, a debriefing session is required in which the experimenter discloses to the subject the use of deception in the research he/she was part of and provides the subject with the option of withdrawing his/her data.
In some U.S. States, informed consent laws (sometimes called "Right To Know" laws) require that a woman seeking an elective abortion be given factual information by the abortion provider about her legal rights, alternatives to abortion (such as adoption), available public and private assistance, and medical facts (some of which are disputed—see fetal pain), before the abortion is performed (usually 24 hours in advance of the abortion). Other countries with such laws (e.g. Germany) require that the information giver not be affiliated with the abortion provider, to avoid giving an economic incentive for handing out faulty information.
Some informed consent laws have been criticized for allegedly using "loaded language in an apparently deliberate attempt to 'personify' the fetus," but those critics acknowledge that abortion information provided pursuant to informed consent laws "most of the information in the materials about abortion comports with recent scientific findings and the principles of informed consent, some content is either misleading or altogether incorrect."
Except for during clinical trials, there is no Federal requirement in the United States for providing informed consent regarding the administration of vaccines. 
No-victim laws 
It may not be legally possible to give consent to certain activities in certain jurisdictions; see the Operation Spanner case for an example of this in the UK which involved sadomasochistic activities such as branding. There are currently several legal challenges underway to address these issues of legality in several nations.[verification needed]
In medical research, the Nuremberg Code set a base international standard in 1947, which continued to develop, for example in response to the ethical violation in the Tuskegee syphilis experiment. Nowadays, medical research is overseen by an ethics committee that also oversees the informed consent process.
As the medical guidelines established in the Nuremberg Code were imported into the ethical guidelines for the social sciences, informed consent became a common part of the research procedure. However, while informed consent is the default in medical settings, it is not always required in the social science. Here, research often involves low or no risk for participants, unlike in many medical experiments. Second, the mere knowledge that they participate in a study can cause people to alter their behavior, as in the Hawthorne Effect: "In the typical lab experiment, subjects enter an environment in which they are keenly aware that their behavior is being monitored, recorded, and subsequently scrutinized."  In such cases, seeking informed consent directly interferes with the ability to conduct the research, because the very act of revealing that a study is being conducted is likely to alter the behavior studied. List exemplifies the potential dilemma that can result: "if one were interested in exploring whether, and to what extent, race or gender influences the prices that buyers pay for used cars, it would be difficult to measure accurately the degree of discrimination among used car dealers who know that they are taking part in an experiment." In cases where such interference is likely, and after careful consideration, a researcher may forgo the informed consent process. This is commonly done after weighting the risk to study participants versus the benefit to society and whether participants are present in the study out of their own wish and treated fairly. Researchers often consult with an Ethics Committee or institutional review board to render a decision.
See also 
- World Medical Association
- Human experimentation
- International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use
- Declaration of Geneva
- Declaration of Helsinki
- Belmont Report
- Human experimentation in the United States
- Safe, sane and consensual
- Informed consent in sociocratic decision-making
- Consent (BDSM)
- Consent (criminal law)
- Consensual crime
- Parental consent
- Minors and abortion
- Informed refusal
- Informed assent
- Mature minor doctrine
- Patient safety
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