Does hypnosis serve as a forensic tool?

Hypnosis is a powerful forensic tool for memory enhancement of witnesses or victims. This tool has been recognized in the last few decades. Let us learn more about this forensic tool.

In forensic settings, hypnosis has been used:

  • To prosecute someone, arguing that it has been used as a coercive/pathogenic tool.
  • As a defense in terms of automation.
  • As a truth machine.
  • To facilitate memory.

The evidence on hypnosis as a coercive tool and generator of out-of-control automatisms indicates that:

  • Under hypnosis, there is no greater risk of committing illegal, immoral, indecent, or self-injurious acts than outside it. The simulators (of being hypnotized) perform them more than the real hypnotized.
  • The hypnotized person does not lose control or awareness of what he is doing: the alleged criminal acts and humiliations carried out or received under hypnosis are understood more as responses already motivated in the person, to please the hypnotist, due to social pressure and the demands of the situation (demand characteristics) of the situation.
  • Hypnosis has no more coercive power than other forms of social pressure or of motivating people to do something inappropriate: it is social control that matters.


Hypnosis as a truth machine

  • There is no evidence that the hypnotized person is compelled to tell the truth. Hypnotized people often fake certain suggested reactions, such as amnesia or hallucinations.
  • There is no criterion for knowing whether or not a person is hypnotized, so they can even lie saying that they are.
  • Few lies are observed in the clinic because of the rapport established between therapist and patient, but no theoretical or experimental reason indicates that the patient cannot lie under hypnosis if she wishes.
  • Hypnosis as a pathogenic tool: The proven risks of hypnosis are:
  • Stop using other procedures believing that hypnosis is an effective therapy for everything and everyone.
  • The creation of false memories, which depends on:
  • The belief that the hypnotized person cannot lie (hypnosis like the truth machine).
  • The belief that hypnosis can generate hypermnesia and precision in recall (e.g., age regression).
  • The leading questions.


Extract of recommendations on the use of hypnosis to promote memory

McConkey & Sheehan (1995) suggest that in forensic settings, at least the following precautions should be taken:

  • Record the session with written consent.
  • Make a previous evaluation of the client’s memory without hypnosis, simply narrating the events.
  • Apply non-hypnotic techniques to increase recall (e.g., repeated recall).
  • Explain the client’s beliefs about hypnosis and its effects on memory.
  • Indicate to the client that hypnosis may or may not aid memory.
  • Assess hypnotic suggestibility.
  • Evaluate the memory under hypnosis with free narration, with and without suggestions for increased memory or age regression.
  • Asking for specific details without leading questions, explaining that it is valid to say that the question is not known, is not remembered, or is not understood.
  • Allow the person to comment on what he wants.
  • Outside of hypnosis, the person should be allowed to comment what he wishes about the memories of her.
  • Establish the impact of hypnosis perceived by the person on her memory.


Excerpt from Guidelines for the Forensic Use of Hypnosis (McConkey & Sheehan 1995)

  • The use of hypnosis should be consistent with legal and clinical safeguards aimed at ensuring the well-being of the subject and other people involved.
  • Hypnosis should not be used with very young children.
  • First of all, the use of hypnosis helps an investigation to generate additional information that can be investigated. Its use is not to generate material that cannot be corroborated in any way, such as emotions, feelings, opinions, and assumptions. Independent corroboration is defined as the evidence that clearly and unequivocally confirms the fact that the crime in question has been committed, and/or has been committed by the accused.
  • The client of forensic interactions on a matter is, first and foremost, the person who is being hypnotized.
  • The hypnotist should be a licensed and registered physician or psychologist.
  • The hypnotist should have the ultimate right to end the session at any time with the needs of the subject in mind rather than the needs of the investigation.
  • The legal rights and well-being of the person should be the primary factors in whatever decisions the hypnotist makes before, during, or after the hypnosis session.
  • The use of hypnosis should be considered routinely with victims and witnesses; only under exceptional circumstances should it be considered with suspects or defendants.



  • Hypnosis does not guarantee the veracity of what is remembered, confessed, or witnessed.
  • Hypnosis cannot be used as an argument to explain that someone was induced to commit acts that he does not want to do (coercion), or that he would not have done under other circumstances of social control (automatism-involuntariness).
  • Hypnosis does not generate a reliable hypermnesia, nor greater than other more reliable ways of improving memory.

Until further research, hypnosis is only useful as a heuristic tool. In general, it is best not to use hypnosis in the forensic setting.