The Brain on Trial

Three experts discuss the rising influence of neuroscience in the courtroom, how advances in neuroscience are posing new challenges for the judicial system, and the use of therapeutic solutions for reforming criminals.

The Researchers

Alan Leshner
Martha Farah
Jay Giedd

Increasingly what we know about the brain is affecting what happens during and after criminal trials. The U.S. Supreme Court, for instance, decided that adolescents could not be eligible for the death penalty partially based on neuroscience evidence that indicated the teen brain is not fully mature. Defense attorneys have also used brain scans to suggest their clients' actions were influenced by brain damage or abnormalities, as part of an argument for modified sentences. And the recent view of drug addiction as a brain disorder has raised questions about how drug addicts should be held accountable for their criminal behavior.

The rising influence of neuroscience in the courtroom was the focus of the Fred Kavli Public Symposium, "The Brain on Trial: Neuroscience and the Law," the symposium was chaired by Alan Leshner, former head of the National Institute of Drug Abuse. One of the key issues this symposium explored was how advances in neuroscience are posing serious challenges for the judicial system, as well as possible solutions for the treatment of criminals.

To discuss this topic, The Kavli Foundation convened Dr. Leshner; cognitive neuroscientist and neuroethics expert Martha Farah, director of the Center for Neuroscience and Society, University of Pennsylvania; and, neuropsychiatrist Jay Giedd, MD, an expert in adolescent brain development at the National Institute of Mental Health and chief of NIMH's Unit on Brain Imaging in the Child Psychiatry Branch.

Together, they covered what role neuroscience should have in determining legal policies and judgments, innovative brain-based treatments for certain pathological behavior, and how we are easily fooled by colorful brain scans. They also shared opinions on whether “painting a picture of the neural processes that give rise to criminal behavior” as Dr. Farah put it, can excuse that behavior or mandate lighter sentencing. Below is the edited transcript of that discussion.

THE KAVLI FOUNDATION: Dr. Leshner, to begin, in the context of neuroscience and the law, what does your field reveal about personal responsibility that you feel is not well understood?

Alan Leshner
Alan Leshner, former head of the National Institute of Drug Abuse.
ALAN LESHNER: There’s been a lot of controversy around the increased understanding that addiction is a brain disease and the implications of that for personal responsibility or law. The fact that you have a brain disease means that biologically, change in your brain has led to compulsive repeated drug use. But it doesn’t mean that you have no responsibility for any of your behavior. Are you less responsible? In a way you are, and that should be taken into account in sentencing; but more to the point, it means we should require treatment while we have drug addicts under criminal justice control because that would decrease significantly the probability they would commit crimes again. Although people may not want treatment initially, they become more involved in it as they are required to participate in drug treatment programs and the treatment is ultimately effective. So I believe drug addicts should be required to go into treatment if they commit an act against society. More criminal justice institutions are implementing treatment while people are under criminal justice control.

TKF: Dr. Giedd, as an expert in adolescent brain development, what is the proper use of your insights into the brain for determining in a courtroom whether a person is responsible for his or her actions?

JAY GIEDD: What the neuroscientist is often asked is, “Was it the person, or was it his or her brain, that made them commit a crime?” To me this is a false dichotomy because the person and the brain are inseparable—everything we think, feel or do, all of our motivations, urges, and our ability to act or not act upon those urges is ultimately a product of our brain activity. This means that, even if we can trace the person’s actions back to the brain, for the most part that doesn’t change the personal responsibility for the crime, which is more of a social, moral, or philosophical issue. There are some rare but remarkable exceptions where someone might have brain damage or a brain tumor that dramatically affects their capacity to make decisions. But most often, it’s not a matter of the brain being qualitatively different from that of other people, and more of the brain reflecting a lifelong accumulation of experiences in which genes interact with the environment in very complex ways. In general, people overvalue the ability of brain imaging or neuroscience to cut through that complexity.

TKF: What about the sentencing of a convicted criminal. Does neuroscience have a role in determining or tempering the legal consequences of a crime, particularly among teenagers?

Jay Giedd
Neuropsychiatrist Jay Giedd, MD, an expert in adolescent brain development at the National Institute of Mental Health.

JAY GIEDD: There currently is debate about whether adolescent brain maturity should be considered in sentencing for a crime or help determine what would be the proper deterrent for future adverse behavior. On average, the 15-year-old brain is different than the 25-year-old brain. What’s difficult is applying this to individuals, as there are so many exceptions to the rule – there are many mature teens, and likewise immature people in their twenties and thirties. So the real challenge is going from group averages to individual prediction or characterization. One pretty strong group phenomenon is that teenagers don’t really think about the future the same way that older people do, so long-term consequences are less of a deterrent to their behavior. Teens are less likely to weigh long-term consequences over the immediate consequences. The other strong adolescent phenomenon is heightened sensitivity to peer pressure. The judicial system could focus on both of these adolescent phenomena when determining deterrents and interventions for adolescent criminal behavior.

TKF: Dr. Farah, what are your thoughts on this topic?

Martha Farah
Cognitive neuroscientist and neuroethics expert Martha Farah, University of Pennsylvania.

MARTHA FARAH: I agree with Jay and Alan. The mere fact that brain processes give rise to the behavior isn’t enough to excuse it. The fact that your behavior had causes doesn’t diminish your responsibility for it in the eyes of the law. But the law does recognize some psychological conditions that diminish responsibility, and if neuroscience knows something about the neural processes underlying these conditions, it can aid in their diagnoses. If the kind of neuroimaging research that Jay does continues for a few more decades, we may well get to the point where we can point to a brain signature in the brain scans of people who have not yet developed an ability to think about the future. Then it would be really reasonable for an attorney to bring in that kind of a brain scan and say, “This young person was developmentally incapable of thinking about the consequences of what he just did.” That would be a case of neuroscience appropriately helping to excuse someone, but it wouldn’t be doing it just by showing there’s a brain basis to the behavior. It would be doing it by showing that a certain psychological ability wasn’t there.

TKF: So is it ever a valid defense to simply say, “My brain made me do it”?

JAY GIEDD: The Charles Whitman case of 1966 comes to mind—he was the Texas tower shooter who killed 16 people and wounded 32 others. Brain scans revealed he had a brain tumor, which may have led to these aggressive, uncontrolled actions. Those cases are so rare, in which there is blatant damage to the brain that is obviously linked to the behavior that occurred, but it certainly can happen. What’s more difficult to discern are the much more subtle brain differences that may not necessarily be linked to the behavior. In these cases, the colorful brain scans introduced in courts can be almost irrationally persuasive. One study showed that if you put in an image into a scientific paper that had nothing to do with the content, other scientists will rate the paper as being more logical and better written, as being more persuasive.

TKF: A picture says a thousand words.

JAY GIEDD: Yes, but not necessarily true words. It’s very seductive to have an aesthetically beautiful brain scan that brings a sense of certainty to something that really isn’t certain. Human behavior is much more nuanced and complex than what some of these images are showing. There are several reasons why brain scans are often misinterpreted and can’t be counted on. One is that you’d really have to be scanning the person at the time of the crime to accurately capture what their brain was like then, because brain states change second-by-second. Another reason is that there’s always the danger of making reverse inferences. An example of a reverse inference is “All dogs have four legs, a chair has four legs, therefore a chair is a dog.” People will look at a brain scan and say “Aha, there’s a bright color indicating heightened activity in this area of the brain that is involved in impulsivity,” even though there are thousands of other activities besides impulsivity that would also cause that same bright color in that spot of the brain. People notoriously overestimate our ability to go from the pictures, aesthetically pleasing as they are, to predicting behavior, to being useful.

TKF: What has been your experience in how neuroimaging plays out in the courtroom?

JAY GIEDD: In the court situations I’ve been involved in, attorneys present me with case histories of incredibly impulsive behavior—of young children hopping into police cars and driving them off without thinking about the consequences, and ask me to do brain scans to see if these kids are impulsive, but that’s a backwards way to approach this. Everything they’ve just said clearly demonstrates that indeed these kids are very impulsive, and if their brain scans show heightened activity in an area that’s involved in impulsivity, okay, but if they didn’t show that, I just wouldn’t believe the images. We can use imaging to tell if someone can do long division just by showing them a problem while they’re in the scanner for about $600, or we can get the same information for three cents just by pulling out a pencil and paper and asking them what’s the answer to a long division problem. It’s a fundamental misconception that the imaging can confirm certain behavioral realities.

TKF: It seems like you are being asked to make a distinction between normal and abnormal behavior based on neuroimaging or other neuroscience evidence. The determination that drug addiction is a disease also suggests we have clear diagnostic endpoints that really distinguish normal from abnormal behavior. But is the evidence ever clear cut in certain cases? Is it really obvious when someone is drug addicted?

ALAN LESHNER: It’s easily determined whether someone is addicted with current diagnostic tools, such as the addiction severity index. But all this knowledge of brain involvement in addiction helps you put the issue in the right box. Traditionally we have thought of addiction only as a criminal justice issue and therefore everything we did related to it had to do with a criminal justice approach. But once you understand that it’s a brain disease and therefore a health issue, you realize the only effective policies in modern society are those that recognize both the health aspect of drug addiction--that drug addicts commit crimes like burglary in order to secure drugs--and that society feels they ought be held responsible for those crimes. The issue for me is not so much what’s the appropriate punitive approach, but what will work best for society. If you don’t deal with the illness or the brain part of drug addiction, you have much less chance of actually reducing the behavior you don’t like, whether it’s drug using or committing crimes. By combining the health approach to the criminal justice approach, I think you have a better chance of having effective and acceptable public policy.

TKF: Do prosecutors ever argue that a brain scan proves a person is hopelessly addicted or has some other problem that suggests they shouldn’t be allowed to join society?

ALAN LESHNER: It does happen, but when that happens it’s a misrepresentation. In fact, we have quite effective treatments for drug addiction that are equally effective as those for other chronic relapsing disorders. It’s not the same as taking penicillin for your strep throat, but there are very effective treatments that can help bring the addiction under control.

MARTHA FARAH: Where the strategy of presenting brain scans as evidence in a trial can backfire is for psychopaths. Psychopaths are likely to commit crimes and, unlike drug addicts, there are no effective treatments for them. So the defense could show a brain scan of a psychopath and say, “Look; this guy’s brain doesn’t work like a normal person’s brain--he’s wired up wrong and couldn’t have shown empathy and moral judgment,” with the aim of getting a lighter sentence. But the judge or jury can hear this and decide it makes him more dangerous and incorrigible so they had better lock him up and throw away the key.

TKF: What role do you think science should have in helping society or the courtroom determine when and how much someone should be held responsible for his or her actions?

ALAN LESHNER: Policy, including criminal justice policy, is always made on the basis of both scientific facts and societal values and we’re never in a situation where you can expect that science will drive the development of policy all by itself. Having said that, I would want to be assured that the science has been fully considered, and that we’re not denying it by diluting or distorting it in the process of making public policy, including criminal justice policy.

TKF: You’re saying that science can provide the facts, but society still has to put a value judgment on top of it?

ALAN LESHNER: Absolutely. It doesn’t have to, it will. You need to recognize that that’s a part of the way the world works.

JAY GIEDD: There are several ways neuroscience can help shape judicial or other social policies, including influencing determinations of appropriate punishments for adolescent crimes or legal age minimums for certain behaviors or political offices. One of the things in the neuroscience of adolescence that is getting more accepted is the importance of learning by example, by modeling. The brain is well suited to learn by example, modeling, and from experience. So incarcerating people in the second decade of their lives will mean their learning will come from other criminals and the judicial system. We have to be aware of the lifelong consequences of having people locked up at this time of life when their brains are specializing based on their experience. The danger is we might have them specialize in being criminals. Also, around the world people are struggling with what should be the appropriate age minimums for voting, driving, becoming a Congressman or president, or having other privileges in society. I think the neuroscience could help with those kinds of policy decisions or laws. Neuroscience findings on adolescents, for example, led to many states adopting graduated driving licenses, which have saved a lot of lives. So neuroscience can be helpful in creating policies related to keeping teens safe and healthy, more so than determining punishment and retribution after they’ve done crimes. Neuroscience may have a place at the table for helping us understand these ideas of competency in major life decisions.

TKF: It sounds like you’re more comfortable making scientific judgments about adolescents as a group as opposed to determining from an individual adolescent’s brain scan whether he or she is prone to abnormal behavior.

JAY GIEDD: Exactly, and that’s really been our greatest challenge, not just for the judicial system, but clinically as well. We can say the average schizophrenic brain is different than that of the average person without schizophrenia, but we can’t put an individual in a scan and tell if they have schizophrenia, or depression, ADHD, autism, etc. There’s a lot of group effort trying to improve our ability to go from the group average to the individual level. The amount of progress we make on that will affect how much neuroimaging findings should influence judicial proceedings.

MARTHA FARAH: Some of the most interesting implications of the neuroscience findings are for how criminals should be punished, as opposed to the question of how responsible they should be for their behavior. We punish for a variety of reasons: for retribution, to incentivize good behavior, and in some cases, to improve the offender. This last one is sometimes called "therapeutic justice"—we send someone to anger management therapy or parenting classes. A lot of good could come from getting society more strongly behind the idea of therapeutic justice. If people’s brains are causing them to do bad things and if we can fix their brains or foster healthier development of their brains, we’ll all be safer. The individual offender is better off and society is better off. So, by putting crime within that public health framework, it makes the idea of therapeutic justice more appealing. As clinical neuroscience advances, it’s actually going to give us ways of accomplishing therapeutic justice.

TKF: So along with being punished, someone’s sentence might include drug therapy to alter how they think and behave?

MARTHA FARAH: The therapy could actually be the sole punishment, or be part of someone’s sentence. We already sentence sex offenders to anti-androgen therapy—chemical castration. And that treatment works on the brain in addition to other parts of the body. It is a central nervous system intervention that’s supposed to help curb their antisocial urges and keep people safer. We may have more such therapies available as neuroscience goes forward.

TKF: So in the future, people might be incarcerated less and instead treated for behavioral offenses.

MARTHA FARAH: Yes, although it does raise the specter of Brave New World and state control of brain processes. The science can tell us what we can do, but society’s values will tell us whether we should do it.

ALAN LESHNER: I agree. And I do believe that people should be required to go into treatment, whether they want it or not, if they are addicted and commit an act against society. You’re not totally controlling the individual with that treatment—it’s not like they are turned into zombies. They go through treatment programs that don’t do away with their free will. It’s important to have a perspective on the degree of mind control that’s being exerted here—it’s not very great. So to second what Martha said, both from a societal standpoint and an individual standpoint, they’re better off getting that treatment.

TKF: What would a therapeutic punishment be for an adolescent whose brain is just not mature enough? There’s no treatment that can speed up that maturity.

JAY GIEDD: The adolescent brain is very plastic and there are things you can do to improve it, from modeling more healthy behaviors to working on impulse control. Brain-based interventions do not have to be deterministic. It’s not like one morning you wake up and your brain’s mature—it’s a very protracted process. But a lot can be done to help adolescents make better choices and have different peer systems. I completely agree with Martha and Alan that it could be a very good thing for that adolescent if they are mandated to get these services that they might not otherwise get because of finances or peer pressures. If we really want to make society safer and better, it would be a very good investment. You can’t move the clock to fast forward, in terms of brain development. But just because someone is an adolescent doesn’t mean you can’t improve their decision-making.

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