One of the finer points in the law on evidence is whether a defendant in a criminal case can present hypnotically refreshed testimony as part of his defense.
What is hypnotically refreshed testimony? In layman’s terms, it is testimony on details of an incident that a party or witness is able to recall after undergoing hypnosis under the supervision of an expert.
In the United Sates, the US Supreme Court has categorically ruled on the issue. In Rock vs. Arkansas, 483 U.S. 44 (1987), the petitioner was accused of shooting her husband with a handgun. However, she could not remember whether she actually pulled the trigger or the gun accidentally fired off. As a result, she twice underwent hypnosis by a trained neuropsychologist. Both hypnosis sessions were recorded. Petitioner did not relate any new information during these sessions. After the hypnosis, she was able to remember that, at the time of the incident, she had her thumb on the hammer of the gun, but had not held her finger on the trigger. She also recalled that the gun had discharged when her husband grabbed her arm during the scuffle. Her counsel arranged for a gun expert to examine the handgun. The inspection revealed that the gun was defective and prone to fire, when hit or dropped, without the trigger being pulled.
Using a rule of evidence in Arkansas, the trial court ruled that no hypnotically refreshed testimony would be admitted, and limited petitioner’s testimony to a reiteration of her statements to the doctor prior to hypnosis, as reported in the doctor’s notes.
On appeal, the Supreme Court of Arkansas upheld the trial court, rejecting petitioner’s claim that the limitations on her testimony violated her constitutional right to present her defense. Although the court acknowledged that “a defendant’s right to testify is fundamental,” it concluded that “the dangers of admitting this kind of testimony outweigh whatever probative value it may have.”
Petitioner brought the issue all the way up to the US Supreme Court where the question was “whether a criminal defendant’s right to testify may be restricted by a state rule that excludes her post hypnosis testimony.”
The US Supreme Court overruled the Arkansas Supreme Court. It held that a criminal defendant has a constitutional right to testify in his own defense. Although the right to present relevant testimony is not without limitation, restrictions placed on a defendant’s constitutional right to testify by a state’s evidentiary rules might not be arbitrary or disproportionate to the purposes they were designed to serve. It then ruled that a per se rule excluding all hypnotically refreshed testimony infringes impermissibly on a criminal defendant’s right to testify on his own behalf. Despite any unreliability that hypnosis may introduce into the testimony, the procedure has been credited as instrumental in obtaining particular types of information. Moreover, hypnotically refreshed testimony is subject to verification by corroborating evidence and other traditional means of assessing accuracy, and inaccuracies can be reduced by procedural safeguards such as the use of tape or video recording. The state’s legitimate interest in barring unreliable evidence does not justify a per se exclusion because the evidence may be reliable in an individual case. Here, the expert’s corroboration of petitioner’s hypnotically enhanced memories and the trial judge’s conclusion that the tape recordings indicated that the doctor did not suggest responses with leading questions are circumstances that the trial court should have considered in determining admissibility.