Insanity test revisions miss the mark.

In the wake of the 1982 insanity acquittal for attempted presidential assassin John Hickley, many states narrowed their legal definitions of insanity in hopes of undermining the attractiveness and success of this controversial defense (SN: 10/6/84, p.218). But extensive data from one of those states demonstrate that the changes had no significant impact on the use of the insanity defense.

Psychologist Margaret A. McGreevy of Policy Research Associates in Delmar, N.Y., and her co-workers gathered criminal and mental health information on all 1,300 defendants who entered insanity pleas in seven California counties from July 1979 through June 1985. A total of 662 received acquittals. California's 1982 revisions, which shifted the burden of proving insanity to the defense and tightened the standard of proof, did not affect the rate of insanity pleas or acquittals, the criminal and mental characteristics of those using the defense or the length of hospital stays for those deemed insane, the researchers report in the June AMERICAN JOURNAL OF PSYCHIATRY.

However, insanity pleas in California steadily declined from late 1980 (before Hinckley's verdict) at least through 1985 for a reason unrelated to the insanity test, McGreevy's team asserts. In 1979, the state adopted determinate sentencing, in which those found insane receive hospital commitments equal to the maximum prison terms for their offense, but with no time off for good behavior. Thus, successful insanity pleas often resulted in hospital stays that lasted considerably longer than prison terms for the same crimes. A clear deterrent, such as determinate sentencing, to the use of the insanity plea packs far more punch than tinkering with the wording of the insanity test, the researchers conclude.