On October 7th, the Supreme Court began its term with the oral argument for Kahler v. Kansas, a case which asks whether a state violates the Eighth and Fourteenth Amendments if it essentially abolishes the insanity defense. The test for due process is traditionally historical, so both Kahler and Kansas focused their briefs on the question of whether the insanity defense is so deeply rooted in history that its elimination would constitute a violation of due process. At oral argument, a few of the Justices probed the difficulties associated with the evaluating historical claims. Their questions suggest that the Court may not view history as a sufficient basis for its decision, and some Justices might not be willing to evaluate historical claims at all.

After separating from his wife in 2008, petitioner, Kraig Kahler, suffered from depression and obsessive-compulsive disorder, but refused to take medicine prescribed by psychologists and psychiatrists. Experts for both the prosecution and defense agree that Kahler demonstrated signs of a major depressive disorder, obsessive-compulsive, borderline, paranoid, and narcissistic personality tendencies. In November 2009, Kahler shot and killed his wife, her grandmother, and his two daughters. The jury found Kahler guilty and sentenced him to death. Per Kansas law, the jury was not permitted to consider Kahler’s mental state and his capacity to distinguish right from wrong as an “affirmative defense.” Rather, they could only consider whether, as a result of insanity, the Kahler lacked the mens rea, or criminal intent, required for the crime.

At oral argument, Justice Breyer raised a hypothetical that demonstrates the difference between Kansas’s approach and the “right-and-wrong” test: “Imagine two defendants. Both defendants, one and two, are certified by whatever board of psychiatrists you want as totally insane. All right? The first defendant shoots and kills Smith. The second defendant shoots and kills Jones. The first defendant thinks that Smith is a dog. The second defendant knows it’s a person but thinks the dog told him to do it.” Under Kansas law, the first defendant, because he did not know he was killing another human being, did not have the criminal intent requisite for murder. By contrast, the second defendant, because he knew he was killing another human being, could not raise his mental illness as a defense.

Kahler argues that because Kansas law does not excuse defendants incapable of determining whether their actions are morally or legally wrong, it violates the Fourteenth Amendment’s due process clause and the Eighth Amendment’s cruel and unusual punishment clause. The Supreme Court has held that a state’s decision with regard to its criminal law is “not subject to proscription under the Due Process Clause unless ‘it offends some principle of justice so rooted in the traditions and conscience of our people as to be ranked as fundamental.’”

The test for due process is therefore traditionally historical, so both Kahler and Kansas focused their briefs on the question of whether the right and wrong test is so deeply rooted in history that its elimination would constitute a violation of due process. Kahler argues that the right-and-wrong principle of punishment has existed at least since the 1500s, and current practice confirms the “fundamental nature” of this test. “Forty-eight U.S. jurisdictions—45 states, the federal criminal-justice system, the military justice system, and the District of Columbia—provide an affirmative insanity defense that encompasses the defendant’s lack of moral culpability.” Kansas contends that the right-and-wrong test is instead a “creature of the nineteenth century,” which “is not so ingrained in our legal system to constitute a fundamental principle of law.” In fact, the variety of insanity defenses recognized by states throughout time indicate that the right-and-wrong test is not deeply rooted in “history and tradition.”

Both of these arguments presume that history will determine the Court’s holding. At oral arguments, many of the Justices resisted this premise, and questioned whether history alone could reliably demarcate the requirements of due process.  There are, Justice Kagan observed, “some ways in which the criminal law of olden times seems remarkably archaic to us now” including the marital rape exception and sodomy laws.  “How do we figure out which [practices] the Constitution requires stay the same . . . and which ones can change?”  Similarly, Justice Ginsburg wondered which elements of history are relevant for the due process analysis. “[C]an we take into account the reality that in the old days at common law, the result of the insanity defense would be you were sent to bedlam, where the conditions were often far worse than in prison?” The Court has not outlined procedural mechanisms for evaluating the merits of historical practice, so Justices Kagan and Ginsburg might be concerned that the Court lacks the tools to consistently parse the historical record. Therefore, a decision based only on historical practice could be arbitrary or misguided. Similarly, Justice Kavanaugh questioned whether the Court would be capable of determining a constitutional floor for due process, and reminded Kahler’s attorney, Sarah Schrup, of Justice Marshall’s plurality opinion in Powell v. Texas, which warned that “[n]othing could be less fruitful than for this Court to be impelled into defining some sort of insanity test in constitutional terms.”

These Justices appear to express concern that a decision on historical grounds alone could be arbitrary—or at the very least, could seem arbitrary. How far in history need a practice extend to be deeply rooted? Is 200 years sufficient? Is 500? Need the practice be observed uniformly? If not, how much conformity is sufficient? Which facets of history should the Court consider and which should it ignore? Neither Kahler nor Kansas could provide the Court clear answers to these questions. Without a principled line on which to base its due process argument, some Justices are likely wondering whether history is a sufficient basis to evaluate this claim. Others might wonder whether the Court should bother evaluating historical claims at all.

Although both conservative and liberal Justices appear to share concern over the difficulty of evaluating historical claims, that concern is likely to manifest differently for different Justices. Justice Breyer, for example, appeared less concerned with historical practice than with whether any rationale could justify excusing a defendant who kills Smith thinking he is a dog, but not a defendant who kills Jones thinking the dog told him to.  Yes states have historically distinguished between these two cases, so could there be a rational basis for that distinction—“something in terms of criminal law or legal purpose or human purpose or whatever that would treat the two . . . differently?” Breyer’s questions appear to suggest that although he might be uncomfortable invalidating Kansas’s scheme on the basis of history alone, he might be willing to invalidate that scheme if it lacks justification in criminal law, legal purpose, or human purpose.

On the other hand, conservative Justices, and those focused on maintaining state autonomy to govern the rules and standards of their criminal justice systems, might reason that because historical analysis would not enable the Court to draw a principled due-process line, states should be free to abolish the right-and-wrong test. As Elizabeth Prelogar, Assistant to the Solicitor General for the United States, contended at oral argument: even if the historical record clearly indicated that due process required “something more” than the mens rea approach, Kahler would not win unless he could “articulate with precision what that something more is.” If Kahler could not meet this burden, Kansas—along with Alaska, Idaho, Montana, and Utah—would be free to find defendants guilty, and potentially subject to capital punishment, even though they lack moral culpability for their conduct.

Although historical analysis is a difficult endeavor, the Court might deny individuals due process if it refuses to engage in that endeavor entirely. If the insanity defense is “so rooted in the traditions and conscience of our people as to be ranked as fundamental,” per Supreme Court precedent, it is protected under the due process clause of the Fourteenth Amendment. If the Court refuses to evaluate whether certain practices are “fundamental,”  it abrogates its duty to protect constitutionally created rights. Moreover, the difficulties associated with parsing historical practice are not unique to the insanity defense. As Justice Kagan indicated, if a historical approach to due process could not save the insanity defense, it may not be able to save the duress defense either. Even if the insanity defense is not “fundamental,” other historical practices may be. Thus, if the Court refuses to ever engage in historical analysis, it could be denying individuals a variety of due process rights.