- Notable Flaws of Hypnosis
- Hypnosis of the Accused
- Hypnosis of a Witness
- Case Law and Expert Evidence
Information obtained under hypnosis should always be treated with great caution.
Whilst there is little authority on the admissibility on post-hypnosis evidence, there is a strong likelihood that such evidence will be deemed unreliable and inadmissible of criminal proceedings.
A person who has been hypnotised should only be called as witness in exceptional circumstances.
Notable Flaws of Hypnosis
Confabulation - Giving False Information under Hypnosis
Information obtained under hypnosis may be true or false. The technical term for false information is "confabulation". It is impossible to distinguish between the truth and confabulation, unless there is independent evidence confirming the information.
A person under hypnosis may be subject to "cueing". This means:
- Explicit or implicit suggestion by the hypnotist;
- Something said long before the session;
- Something that the witness just happened to be thinking about;
- A fantasy of the witness.
During hypnosis these can become fixed as facts in the mind of the subject. There is no reliable means of guarding against this happening.
Furthermore, subjects of hypnosis frequently report as being more confident of post-hypnotic memories, regardless of their accuracy.
Hypnosis of the Accused
Any confession obtained by hypnosis is likely to be ruled inadmissible under sections 76 or 78 Police and Criminal Evidence Act 1984.
Under no circumstances should suspects or persons who may be implicated in the commission of an offence be hypnotised.
Hypnosis of a Witness
The police will sometimes arrange for a witness to be hypnotised in the hope that he or she will recall further details under hypnosis
You should advise the police to restrict the use of hypnotism to people who may be able to give them a lead on an investigation but who will not be called as witnesses.
There may be exceptional circumstances where the witness whom the police wish to hypnotise is the victim of the crime and also the sole witness. It is highly desirable to look for corroboration of any evidence obtained under hypnosis before allowing a prosecution to proceed.
A witness who has been hypnotised will often tell a story full of detail which may appear utterly convincing. No expert will be able to tell if it is the truth or confabulation. The story told under hypnosis will become so firmly fixed in the subject’s mind that they may become unshakeable in cross examination.
It is probable that the court will exclude the evidence of a witness who has been hypnotised under section 78 Police and Criminal Evidence Act 1984 on the basis that it would have such an adverse effect upon the fairness of the proceedings that it would be unfair to admit the evidence.
Where there is insufficient evidence to proceed without calling a witness who has been hypnotised, you should exercise great caution before deciding that the evidence of the hypnotised witness will create a realistic prospect of conviction.
Any material associated with the hypnosis of a witness, whether called as a prosecution witness or not, should be treated as unused material.
If you are proposing to rely on a witness who has been hypnotised, you should check if the session was recorded on audio or videotape. Any recording will be disclosable as unused material. See Disclosure Manual, Tape recorded interviews and Video Recorded Evidence (Special Measures) elsewhere in the Legal Guidance.
Even if the session was not recorded, it will always be appropriate to advise the defence of the fact that the witness has been hypnotised and the details of the session
It may prove necessary to call the hypnotist to give evidence. There is no case law as to the extent to which the hypnotist’s evidence may be relevant.
Cases in which a hypnotised witness is to be called will nearly always be of unusual complexity and sensitivity and they should be notified to the Chief Crown Prosecutor or Deputy Chief Crown Prosecutor. See Referral of Cases legal guidance.
Case Law and Expert Evidence
In the case of R v Browning  Crim LR 227 CA, the Court of Appeal stated that the use of hypnosis should be exceptional and that it should not normally be considered in relation to witnesses who might be called to give material evidence.
In the case of R v C  EWCA Crim 231, the prosecution served, as unused material, a statement from a hypnotherapist. The complainant had disclosed to the hypnotherapist, whilst under hypnosis, that the defendant had sexually abused them. The defence instructed an expert who was critical of the hypnotherapist’s methods and sought to admit this evidence as to the dangers of false memory arising under hypnosis. The defence also sought to have the complainant’s evidence excluded under Section 78 PACE1984. The trial judge ruled that the defence expert’s evidence was inadmissible and the defendant was convicted.
On appeal, the Court of Appeal held that the trial judge was right not to exclude the complainant’s evidence under Section 78 PACE 1984. However, they also held that the defence expert’s evidence was admissible to furnish the court with scientific information which was likely to be outside the experience and knowledge of a judge or jury. As a result, the convictions were deemed unsafe and a retrial was ordered.
Whilst the case of Fennell v Jerome Property Maintenance Ltd, The Times, 26 November 1986, QBD is a civil judgment, the following was noted: “evidence produced by the administration of a mechanically or chemically or hypnotically induced test on a witness so as to show the veracity or otherwise of that witness is not admissible in English law.”
When considering novel scientific evidence, Practice Direction 19A.1 of the Criminal Procedure Rules governs the admissibility of expert evidence: “expert opinion evidence is admissible in criminal proceedings at common law if, in summary, it is relevant to a matter in issue in the proceedings, it is needed to provide the court with information likely to be outside the court's own knowledge and experience; and the witness is competent to give that opinion.”
In R v. Dlugosz; R. v. Pickering; R. v. S. (M.D.)  1 Cr.App.R. 32, the Court of Appeal observed: “in determining the issue of admissibility the court must be satisfied that there is a sufficiently reliable scientific basis for the evidence to be admitted. If there is then the court leaves the opposing views to be tested before the jury.”
In Trochym v The Queen, 216 C.C.C. (3d) 225, the Supreme Court of Canada held that a party wishing to rely on novel, scientific evidence must first establish that the underlying science is sufficiently reliable to be admitted in a court of law.
The Privy Council in Lundy v R  UKPC 28 provided further guidance, which should be considered when assessing the admissibility of new or novel scientific techniques.
For a more in-depth look at expert evidence, particularly around novel or new scientific techniques, please see the standalone CPS legal guidance chapter on ‘Expert Evidence’.