Rock v. Arkansas

In Rock v. Arkansas, 483 U.S. 44 (1987), the U.S. Supreme Court overturned a conviction because a state law prohibited any testimony refreshed by hypnosis, and this prevented the defendant herself from testifying as to her recollection of the crime as refreshed by hypnosis.

The defendant, accused of a killing to which she was the only eyewitness, was allegedly able to remember the facts of the killing only after having her memory hypnotically refreshed. 483 U.S. at 46. Because Arkansas excluded all hypnotically refreshed testimony, the defendant was unable to testify about certain relevant facts, including whether the killing had been accidental. See 483 U.S. at 47-49. In holding that the exclusion of this evidence violated the defendant's "right to present a defense," the Court noted that the rule deprived the jury of the testimony of the only witness who was at the scene and had firsthand knowledge of the facts. 483 U.S. at 57. This rule infringed upon the accused's interest in testifying in her own defense—an interest that the Court deemed particularly significant, as it is the defendant who is the target of any criminal prosecution. See 483 U.S. at 52. For this reason, the Court stated that an accused ought to be allowed "to present his own version of events in his own words." Id.

Chief Justice William Rehnquist and Justices Byron White, Sandra Day O'Connor and Antonin Scalia dissented, stating that:

The Supreme Court of Arkansas' decision [excluding the testimony] was an entirely permissible response to a novel and difficult question. See National Institute of Justice, Issues and Practices, M. Orne et al., Hypnotically Refreshed Testimony: Enhanced Memory or Tampering with Evidence? 51 (1985). As an original proposition, the solution this Court imposes upon Arkansas may be equally sensible, though requiring the matter to be considered res nova by every single trial judge in every single case might seem to some to pose serious administrative difficulties. But until there is much more of a consensus on the use of hypnosis than there is now, the Constitution does not warrant this Court's mandating its own view of how to deal with the issue.