Law & Psychiatry: Insanity, Guilty Minds, and Psychiatric Testimony

Rarely does the U.S. Supreme Court enter the legal thicket surrounding criminal defenses involving insanity, diminished capacity, and related states of mental impairment. As a rule, the Court prefers to leave these issues to be resolved by the jurisdictions in which they arise, as matters of state law. Thus considerable surprise and speculation attended the Court's decision last year to hear a case that addressed the constitutional dimensions of both the insanity defense and the slippery legal concept of mens rea (Latin for a "guilty mind").

The case accepted by the Court involved Eric Clark, who was 17 years old at the time of his arrest and who had been acting oddly for years. Convinced that Flagstaff, Arizona, where he lived, had been populated by hostile space aliens, he slept surrounded by an alarm system made from fishing line and wind chimes. To avoid being poisoned by his parents, who he ultimately concluded were aliens as well, the only food he ate at home came from sealed packages. Perhaps most fatefully, Eric Clark decided that the police were aliens too. So it seemed the logical, if awful, culmination of his paranoid fantasies that early on a June morning he shot and killed a Flagstaff police officer who had pulled him over as he was driving erratically through a residential neighborhood ( 1 ).

Charged with first-degree murder for knowingly or intentionally killing a police officer, Clark offered two alternative defenses based on his mental state at the time of the crime. First, he argued that he should be found "guilty except insane"—Arizona's formulation of the insanity defense—because of his psychotic state. Under Arizona law, Clark needed to prove that his mental disorder rendered him unable to understand the wrongfulness of his conduct—part of the historic M'Naghten standard for insanity. Clark argued that his delusions had prevented him from knowing that killing the officer, who he thought was an alien who was trying to harm him, was wrong.

In the event that his insanity claim was unsuccessful, Clark also contended that he lacked the required intent (or, in legal terms, mens rea) for the crime with which he was charged, because his delusions interfered with his knowing that the victim was a police officer. Given that the charge he faced was first-degree murder for "intentionally or knowingly killing a law enforcement officer who is in the line of duty," Clark argued that his belief that the officer was an alien should preclude his being found guilty of the charge. If successful with this argument, Clark could still have been found guilty of second-degree murder or manslaughter, neither of which requires knowledge that his victim was a police officer and which carry lesser punishments. However, Clark faced a substantial hurdle in making the case that he lacked mens rea: Arizona law bars courts from considering evidence concerning mental disorders when adjudicating mens rea claims ( 2 ).

Notwithstanding his double-barreled defense, Clark was convicted as charged and sentenced to a 25-year prison term ( 3 ). On appeal, he challenged Arizona's definition of legal insanity on due process grounds, alleging that it was too narrow to be constitutionally acceptable, and he also objected to the state's preclusion of evidence regarding his mental disorder from being introduced to support the claim that he lacked mens rea. He lost both claims in the Arizona Court of Appeals, and when the state's supreme court refused to consider his arguments, he filed for a writ of certiorari from the U.S. Supreme Court. Neither the scope of the insanity defense nor the question of the evidence appropriate to establish the absence of mens rea had ever been addressed directly by the Court. So when the justices agreed to hear the case, the potential for a precedent-setting decision was apparent.

As far as the insanity defense was concerned, however, the Supreme Court was clearly not inclined to strike out in new directions. Clark had argued that Arizona's insanity test was impermissibly narrow, because the state had dropped half of the traditional M'Naghten standard, namely whether the defendant knew the "nature and quality of his act." As noted, Arizona relies entirely on a determination of whether the defendant knew that what he was doing was wrong. Writing for a six-person majority on the major issues in the case, Justice Souter rejected the notion that any particular standard for criminal insanity was required by the constitution ( 4 ). He noted "the insanity rule, like the conceptualization of criminal offenses, is substantially open to state choice," and "due process imposes no single canonical formulation of legal insanity."

Moreover, Souter argued that Arizona's constriction of the M'Naghten rule to just one of its components worked no practical detriment to defendants. Citing Abraham Goldstein's influential 1967 book on the insanity defense ( 5 ), he pointed out that anyone who failed to comprehend the "nature and quality of his act" would not be likely to understand that the act was wrong. Thus, the fragment of the M'Naghten test that Arizona still embraced was as fully protective of defendants' interests as the original, more complete formulation. As for whether the constitution requires some sort of insanity defense (four states have abolished a defense of insanity altogether), Souter and his colleagues simply declined to address the issue. Because the decision in the Clark case merely upholds the status quo, its implications for the use of the insanity defense are minimal.

However, the Court's decision on Clark's challenge to Arizona's rules regarding mens rea may have a broader impact, although more for its reasoning than its conclusion. Few legal concepts are as complex as mens rea, and successful defenses based on the claim that mens rea is lacking are uncommon. Every crime requires some degree of mens rea, usually intent to commit a particular act but sometimes just an attitude of recklessness or even inattention; for a small number of crimes (for example, speeding) mens rea is simply presumed, an approach referred to as "strict liability" ( 6 ). Arizona is one of 13 states that exclude evidence related to the impact of a defendant's mental disorder on mens rea, and it was that aspect of the state's law that Clark challenged.

Why would a state adopt a rule like Arizona's that evidence of a mental disorder can be considered only in connection with an insanity defense but cannot support a defense based on lack of mens rea? States may fear that defense attorneys would otherwise have overly broad scope to introduce mental health testimony, turning almost every case into a contest among experts. There may also be a reluctance to afford defendants what appears to be another route for escaping (or more likely mitigating) punishment. Yet 37 states allow such testimony regarding mental disorders, and there is no reason to believe that the criminal justice process in those jurisdictions has ground to a halt.

Indeed, Justice Souter began his analysis by acknowledging that testimony about mental disorders will usually be directly relevant to a mens rea claim. But states have the right to exclude even relevant testimony for good enough reasons. Souter pointed to two reasons that could support Arizona's approach. First, he suggested that it can be easier for a defendant to win a mens rea claim than an insanity defense. States can place the burden of persuasion regarding an insanity defense on the defendant, and Arizona actually requires defendants to overcome the presumption of sanity by clear and convincing evidence, a moderately stringent standard. But the prosecution always has the burden of proving mens rea beyond a reasonable doubt, at least once the defendant raises any evidence to challenge presumptions about his intent. The majority held that it was legitimate for states to channel evidence of mental disease solely to questions of insanity, so as not to allow defendants a less stringent route to a successful defense.

Oddly, after making this argument, the majority conceded that it carries little persuasive power. The law, after all, has always required the prosecution to prove both a criminal act and the relevant state of mind; why should states be allowed to handicap defendants who seek to introduce relevant evidence on this critical issue? Souter suggested that evidence about mental disorders has several characteristics that permit a state to exclude it: there is often debate about which criteria should be used to define diagnostic categories; jurors may be confused by evidence about mental disorders, believing that the presence of illness necessarily implies lack of capacity to form mens rea; and testimony on the ultimate issue of mens rea by mental health experts may carry unwarranted authority. Thus, although the majority would require that lay testimony on a defendant's state of mind be admissible, it supported Arizona's power to exclude expert testimony.

In part, the majority opinion rests on a rather shaky empirical assumption: lack of mens rea is easier to assert—especially if expert testimony is permitted—than insanity. Not many people with experience in the criminal justice system would endorse that conclusion. Certainly the four states that have abolished the insanity defense, restricting defendants with mental disorders to claims that they lacked mens rea, did not think that they thereby were making things easier for defendants. As uncommon as successful insanity defenses are, mens rea acquittals are rarer still. Moreover, proof that an individual lacked the specific intent required for a crime usually means that the defendant will be convicted of a lesser degree of crime, not that he or she will be exonerated completely.

Perhaps more troubling is the majority's willingness to conjure the specters of unreliable definitions of mental illness and jurors' being misled by expert testimony. As Justice Kennedy's dissent noted, the majority's rule "excludes evidence no matter how credible and material it may be in disproving an element of the offense." In this case, there was no dispute that Clark had schizophrenia and that evidence regarding his delusions was material to his mens rea claim. Nor, given that the case was tried before a judge, was there concern about confusing a jury. Because Arizona allows decisions to be made on a case-by-case basis regarding the admissibility of psychiatric evidence on a wide variety of issues, Kennedy and the two justices who joined him in dissent saw no reason why a similar process could not be followed here. Indeed, they suggested that failure to allow such testimony will only increase the confusion of legal factfinders, who will hear descriptions of a defendant's behavior but be denied the explanations that an expert can provide.

Two predispositions appear to underlie the majority decision in Clark, both of them troubling. Doubt about the demonstrable reality of mental disorders is a subtext in the opinion, embodied in references to "vigorous debate" and "professional ferment" regarding diagnostic boundaries. The Court's wholesale rejection of mental health expert testimony—rather than adopting a case-by-case approach—seems to be based on the belief that mental disorders are somehow less real than other illnesses. Similar preconceptions appear to underlie the Court's apparent contention that jurors—who routinely hear from economists, engineers, ballistics experts, and other purveyors of arcane knowledge—will find mental health evidence uniquely confusing.

In addition, the majority decision seems motivated by an inclination to disfavor defendants. The Court has had no problem upholding the admissibility of psychiatric testimony in death penalty cases, even where it is undertaken without examining the defendant and used by the state to demonstrate a likelihood of future violent behavior. Indeed, the justices rejected the American Psychiatric Association's argument that these determinations were so unreliable that they should be excluded by responding, "The suggestion that no psychiatrist's testimony may be presented with regard to dangerousness is somewhat like asking us disinvent the wheel" ( 7 ). A cynical view might suggest that the Court will permit the introduction of expert mental health testimony when it disadvantages defendants but will find reasons to support its exclusion when it works to defendants' benefit.

The legacy of Clark v. Arizona is not likely to relate to either of the substantive holdings regarding insanity or mens rea. In both areas, the Court left the status quo unchanged. The case's unhappy testament will probably be the skepticism that the Court displayed about evidence of mental disorders. Such attitudes have the potential to exert unfortunate influences on lower court decisions involving mental health issues in areas far removed from criminal law.