Dr. Beatriz Luna is an associate professor of psychiatry and psychology at the University of Pittsburgh Medical Center and the director of the Laboratory of Neurocognitive Development, where she uses neuroimaging methods to understand the development of voluntary control.
UPDATED JANUARY 21, 2011, 12:22 PM
The emergence of neuroscience methods that have the ability to characterize brain behavior have the promise of informing the justice system in issues like the insanity plea. However, these methods have not reached the level of identifying if an individual is a criminal and may never reach that level.
Neuroimaging methods can potentially inform the law as to whether someone has the capacity to make knowing and purposeful acts.
Even if neuroscience could provide some notion of the character of a person, the free will that the law protects may not be identifiable by neurobiological markers alone. Neuroscience can only inform the law about one of the many circumstances that underlie a criminal act. It cannot determine the ultimate culpability of a crime, which is an ethical issue.
Neuroimaging methods can potentially inform the law as to whether someone has the capacity to make knowing and purposeful acts. In cases where a person with a psychiatric disorder commits a crime, it may very well be knowingly and purposeful.
For example, Jared Loughner’s criminal act appears to have involved careful planning that required voluntary and well-thought out steps. However, the aim of this planned behavior may reflect a disordered, diseased state. Neuroimaging studies could show that such a criminal engages brain systems to support voluntary acts in a similar way as the normal population. However they could also show abnormalities in brain processes that support the ability to have empathy and control over anger, or show that reported hallucinations recruit brain processes that support real sensory experiences. Although such a person would be able to operate in a voluntary planned manner, their acts would reflect brain abnormalities that contribute to their urge to commit crimes.
Should such a disorder be an excuse for their voluntary behavior? Probably not, but it might provide extenuating circumstances that could influence sentencing.
The Insanity Defense Has Little To Do With Science
Dr. William T. Carpenter Jr. is a professor of psychiatry and pharmacology and the director of the Maryland Psychiatric Research Center at the University of Maryland School of Medicine. He was an expert witness in the Hinckley trial.
UPDATED JANUARY 21, 2011, 12:16 PM
Psychiatrists have a high degree of agreement in ordinary clinical settings regarding a diagnosis like schizophrenia. Disagreement is most common early in the course of illness when diagnosticians may agree on a psychotic illness -- a break from reality associated with false beliefs, hallucinations and disturbance in the flow of thought -- but be uncertain as to whether the overall pattern will be schizophrenia, or bipolar disorder, or drug-induced psychoses or one of a number of other specific psychotic disorders.
Science has advanced knowledge on the genetic and environmental origin of these disorders. Neuroimaging studies have made clear where and how development and function of the brain has been disturbed. A range of laboratory assessments of cognition and electrophysiology reliably distinguish psychotic disorders from non-ill controls.
Despite many advances in understanding the disorders, science has not yet produced biomarkers or diagnostic tests that are sufficiently specific for each diagnosis to be applied in individual cases. This need not, however, deter courts in considering an insanity defense. The courts in most states recognize schizophrenia, for example, as a psychotic illness that qualifies for this defense. Most cases are resolved without trial and often with extensive agreements among experts. Those that go to trial may often have agreement as to diagnosis, at least at the level of psychotic symptoms.
The insanity defense is not based on the presence of illness, but on whether the person, because of the illness, met the standard at the time when the crime was committed. Science has not, and probably cannot, answer this question. This is for the jury. If the diagnosis of psychosis is in doubt, the jury may conclude that the defense is not based on a qualifying diagnosis. If psychosis is present, the jury must the weigh all the information and determine whether, at the time of the crime, the standard is met.
In the post-Hinckley era, the standard in many states has become a simple cognitive test that has little relationship to the scientific or clinical knowledge regarding psychotic illness. Rather than state of mind and the defendant's understanding of his or her actions, the standard is close to simply whether the defendant knew the act was unlawful. Insanity acquittals, already rare, now face an almost impossible standard.
Justice vs. Fear
David I. Bruck is a clinical professor of law and directs the Virginia Capital Case Clearinghouse, a death penalty defense legal clinic at the Washington & Lee School of Law.
UPDATED JANUARY 21, 2011, 12:16 PM
The criminal law has become much more hostile to the insanity defense since 1981. After the Hinckley verdict, for example, Congress barred federal courts from finding defendants legally insane “merely” because they were too mentally ill to have avoided committing the crime. It also put the burden of proving insanity on the accused, not the prosecution, and raised the defense’s burden of proof to a very demanding “clear and convincing” standard (that means a jury must convict even if it thinks the defendant was probably not legally responsible, so long as the question is a close one).
Even if found not guilty by reason of insanity, an offender can be locked up for life in a secure psychiatric facility.
If a mentally ill offender overcomes all those obstacles and manages to be found not guilty by reason of insanity, the federal court retains the power to keep him or her locked up — potentially for life — in a secure psychiatric facility. And lest that last change might reassure jurors that they could acquit a mentally ill offender without endangering society, the Supreme Court has ruled that judges don’t have to tell juries anything about the system for locking up dangerous offenders after insanity acquittals.
The result is a legal system that almost guarantees that jurors will reject even the most valid insanity defense out of misplaced fear of putting a violent person back on the street.
Insanity defenses have always been rare, and so this stacked deck doesn’t come into play very often. But the way we treat severely mentally ill offenders implicates the moral legitimacy of our whole system of criminal law.
We tell ourselves that we convict and punish criminals to hold them responsible for the harm that they have chosen to inflict on others. But what about an offender who is actually not responsible due to severe mental illness? Punishing him — with the especially harsh sentences that characterize the American criminal justice system — carries no moral message. It just hurts and degrades someone who could have been any of us, or anyone we love.
That’s why the insanity defense — and the fairness with which our courts evaluate it — is a measure of our commitment to a system of criminal law based on justice rather than fear. And by that measure, 30 years after Hinckley, our commitment to justice looks a little shaky.
A Moral, Not a Medical, Question
Kent Scheidegger is the legal director of the Criminal Justice Legal Foundation.
UPDATED SEPTEMBER 18, 2013, 2:53 PM
The insanity defense is more precisely a plea of "not guilty by reason of insanity." This phrasing puts the emphasis where it belongs, on whether the defendant is guilty. Whether he is "insane" is relevant only to the extent it bears on whether he is guilty.
Guilt is a legal and moral construct, not a medical one. The traditional test is whether the defendant was able to understand the nature of the act and understand that it was wrong. This test was established by an English court in a 19th century assassination case and reestablished by Congress after John Hinckley was acquitted for shooting President Reagan. It remains the proper legal and moral test. A person who understands what he is doing and that it is wrong but does it anyway is morally responsible for his act.
Advances in brain science are relevant to application of the test to the extent they clarify what the defendant is capable of understanding, but in reality they have not clarified that much. PET scans make pretty pictures that impress juries, but the experts who point to a red spot and claim that the spot means the defendant could not help himself are engaging in a kind of high tech phrenology that is not much more valid than the old kind.
Schizophrenia is a terrible illness, and in some cases it is a powerful mitigating circumstance to be considered in sentencing. That is why the Unabomber was sentenced to life and not death. However, very few people are so split off from reality as to be deemed innocent of crimes of violence. The insanity defense rarely succeeds, and that is how it should be. Nothing we have learned about the brain in the last three decades changes that.