§ 24.09 HYPNOTIC EVIDENCE

• Jurisdiction: United States

§ 24.09. HYPNOTIC EVIDENCE

In 1897, the California Supreme Court wrote that the "law of the United States does not recognize hypnotism."¹⁶⁸ The issue did not resurface until the 1970s, when the use of hypnosis in criminal cases increased significantly. In 1980, a New York trial court observed: "The past ten years have seen a dramatic rise in the use of hypnotism as an aid in criminal investigations."¹⁶⁹

The principal evidentiary issues concerning hypnotic evidence involve: (1) the admissibility of out-of-court statements made by a person while hypnotized; (2) the admissibility of testimony of a witness whose memory has been "refreshed" by hypnosis; and (3) the admissibility of expert testimony concerning the accused's mental condition when based on an interview in which hypnosis was employed.

[A] Out-of-court Hypnotic Statements

Courts uniformly have rejected the admissibility of statements made by a person while hypnotized. Since these statements are made out of court and are offered for their truth, they are hearsay if offered by the accused. Moreover, "[m]ost experts agree that hypnotic evidence is unreliable because a person under hypnosis can manufacture or invent false statements. A person under a hypnotic trance is also subject to heightened suggestibility."¹⁷⁰ The prosecution's use of such statements raises similar reliability concerns. In Leyra v. Denno,¹⁷¹ the Supreme Court ruled that a confession obtained by a "psychiatrist with considerable knowledge of hypnosis" was involuntary and thus violative of due process.

[B] Hypnotically-refreshed Testimony

Courts are sharply divided over the admissibility of hypnotically-refreshed testimony.¹⁷² Some courts adopt a per se rule of exclusion, albeit with some exceptions. Courts admitting hypnotically-refreshed testimony have taken three different positions: (1) a "credibility" approach, which leaves the reliability issue to the jury, (2) a "discretionary admission" approach, which entrusts the reliability issue to the trial judge, and (3) a "procedural safeguards" approach. In addition, constitutional concerns have played a role in some aspects of these cases.

Per se exclusion. This position is based on the belief that hypnotically-refreshed testimony is unreliable.

Three general characteristics of hypnosis may lead to the introduction of inaccurate memories: the subject becomes "suggestible" and may try to please the hypnotist with answers the subject thinks will be met with approval; the subject is likely to "confabulate," that is, to fill in details from the imagination in order to make an answer more coherent and complete; and, the subject experiences "memory hardening," which gives him great confidence in both true and false memories, making effective cross-examination more difficult.¹⁷³

Courts adopting the per se rule of exclusion, however, carve out an exception for testimony based on prehypnotic memory. For example, in State ex rel. Collins v. Superior Court,¹⁷⁴ several rape victims were...