Catering to this view, about 20 states have introduced the verdict of “guilty but mentally ill,” which holds a person legally accountable for a crime but permits mental illness to be considered as a mitigating factor in sentencing. This verdict is supposed to enable an ill individual to receive the treatment he or she needs. In reality, those deemed guilty but mentally ill sometimes fail to receive adequate therapy. What is more, the verdict has not led to a clear-cut reduction in the number of insanity acquittals.
Whether or not the insanity defense is justified, it is intended only for the rare instances in which a bona fide mental disorder has obliterated the psychological brakes most of us use to stop ourselves from acting immorally. Yet many Americans perceive the insanity defense to be widely invoked and commonly successful. In a 2007 study psychologist Angela Bloechl of the University of Wisconsin–Oshkosh and her colleagues found that college students estimate that the defense is used in 30 percent of criminal cases and succeeds 30 percent of the time.
Yet data from multiple studies show that only about 1 percent of cases involve the plea, and only 15 to 25 percent of those result in acquittals. Although notorious insanity plea acquittals, such as those of Yates and Hinckley, garner outsize media attention, scores of other defendants, including Jack Ruby (who killed Lee Harvey Oswald, John F. Kennedy’s assassin), David Berkowitz (“Son of Sam”), Jeffrey Dahmer (serial killer) and Lee Boyd Malvo (one of the two Beltway snipers), have been convicted after pleading insanity.
Many people also believe that those acquitted on the basis of insanity get a quick and easy pass out of prison. “A few years of treatment in a mental hospital, then presto! She’s all better now, free to be released into an unsuspecting public,” Gallagher speculated about Yates. But only about 1 percent of those who use the insanity defense successfully are released immediately, and the average length of hospital stays for people let off because of insanity is about three years. Indeed, as of this writing, Yates remains institutionalized in a mental hospital in Kerrville, Tex., more than four years after her acquittal. Moreover, data collected in 1995 by sociologist Eric Silver, then at Policy Research Associates in Delmar, N.Y., suggest that those deemed not guilty by reason of insanity often remain in institutions just as long as people convicted of comparable crimes do; in some states, such as New York and California, they stay longer.
Thus, the insanity defense is far from a quick passage to freedom. Citizens and policy makers must understand the plea for what it is: an extremely rare exception that proves the rule that almost all individuals should be held legally responsible for their criminal actions.
This article was originally published with the title The Insanity Verdict on Trial.