Rock v. Arkansas

Supreme Court of the United States · 1987 · Evidence

483 U.S. 44 (1987)

Updated August 1, 2026

Evidencehypnotically refreshed testimonyright to testifydue processcompulsory processFifth AmendmentSixth AmendmentFourteenth Amendment

Facts

After petitioner was charged with manslaughter for shooting her husband, her attorney suggested hypnosis because she could not remember the precise details of the shooting. A licensed neuropsychologist hypnotized her twice, recorded both sessions, and petitioner later recalled that she had her thumb on the hammer rather than her finger on the trigger and that the gun discharged when her husband grabbed her arm. A gun expert then found the handgun was defective and prone to fire without the trigger being pulled. The trial court excluded all hypnotically refreshed testimony and allowed petitioner to testify only to matters remembered and stated before hypnosis.

Issue

Whether Arkansas’ per se evidentiary rule prohibiting admission of a criminal defendant’s hypnotically refreshed testimony violated the defendant’s constitutional right to testify on her own behalf. More specifically, the question was whether the State could categorically exclude all posthypnosis testimony as unreliable.

Rule

A criminal defendant has a constitutional right to testify on her own behalf, grounded in the Fourteenth Amendment’s due process guarantee, the Sixth Amendment’s Compulsory Process Clause, and as a corollary to the Fifth Amendment privilege against compelled testimony. Restrictions on that right may not be arbitrary or disproportionate to the purposes they are designed to serve, and a State’s interest in excluding unreliable evidence does not justify a per se exclusion of all hypnotically refreshed testimony by a defendant absent clear evidence that all such testimony is invalid.

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One of 10 multiple-choice questions for this case. Pick an answer to see why.

In a homicide trial in Ohio, Dana Mercer wants to testify that after two hypnosis sessions she remembered the victim grabbed her wrist just before the gun discharged. The sessions were video recorded, conducted by an independent psychologist, and a firearms examiner found a defect consistent with Dana's account. Ohio has a rule automatically barring any criminal defendant from testifying to any memory first recalled after hypnosis.

Is application of the Ohio rule constitutional?

Explanation. A criminal defendant has a constitutional right to testify on her own behalf, and restrictions on that right may not be arbitrary or disproportionate to their purposes. A per se rule excluding all posthypnosis testimony of a defendant is unconstitutional because the State's interest in reliability does not justify wholesale exclusion absent clear evidence that all such recollections are invalid. Recording and corroboration strengthen the argument for admissibility, but the key defect is the categorical rule.