Broken Brains on Trial: An Interview with Kevin Davis

tags: interview, Kevin Davis, The Brain Defense

Robin Lindley is a Seattle-based writer and attorney, and the features editor of the History News Network ( His articles have appeared in HNN, Crosscut, Salon, Real Change, Documentary, Writer’s Chronicle,, Alternet, and others. He has a special interest in the history of conflict and human rights. His email:

Kevin Davis

In January 1991, retired advertising executive Herbert Weinstein, 65, strangled his wife during an argument and threw her from a window of their twelfth story Manhattan apartment. He confessed to this horrific homicide, but could not understand how it happened. Weinstein had no history of violent behavior and family members and friends described him as quiet, unassuming, and never prone to anger. His attorney, Diarmuid White, arranged for neurological testing of Weinstein and an MRI of the brain revealed a cyst the size of an orange in the frontal lobe, the brain area responsible for impulse control and judgment. At trial, Weinstein’s lawyer presented this evidence of brain damage and argued that the cyst interfered with his client’s judgment and that he should not be held criminally responsible for his actions.

This intriguing case serves as a jumping off point for award-winning author and criminal justice expert Kevin Davis in his new study of the intersection of law and neuroscience, The Brain Defense: Murder in Manhattan and the Dawn of Neuroscience in America’s Courtrooms (Penguin Press). As Mr. Davis follows the intricacies of the landmark Weinstein case through the judicial system he interweaves the history of brain injuries and aberrant behavior; the evolution of the insanity defense; findings on the developing brains of children and juveniles; and recent research on the effects of repetitive head trauma (chronic traumatic encephalopathy) and blast injuries (traumatic brain injuries) on the human brain.

Mr. Davis carefully examines “the brain defense”—the increasing use of clinical evidence of brain injury by criminal defense attorneys either to establish innocence or to mitigate punishment during sentencing. He considers how the legal system has changed in determining questions of responsibility, punishment, and rehabilitation in criminal cases with the burgeoning use of this sophisticated medical evidence. And Mr. Davis suggests that neuroscience may illuminate a path to a more fair and compassionate justice system by providing an improved the understanding of the human mind.

The Brain Defense is based on Mr. Davis’s original research, including extensive archival work and interviews with leading neuroscientists and lawyers at the forefront of the new field of “neurolaw.” Reviewers have praised his book for its vivid storytelling, thorough research, and illuminating consideration of the burgeoning use of brain science in legal matters.

Kevin Davis is an award-winning journalist and author with a special expertise in the criminal justice system. His other books include The Wrong Man and Defending the Damned. He is a former crime reporter for the South Florida Sun-Sentinel, and his writing has appeared in numerous periodicals from USA Today, the Los Angeles Times, Chicago Tribune, and Chicago Magazine, to Utne Reader, In These Times, ABA Journal, and many others. He teaches nonfiction writing at the University of Chicago Graham School of Continuing Liberal and Professional Studies, and has taught a writing class for detainees at the Cook County Jail.

Mr. Davis generously responded by email to a series of questions on The Brain Defense.

Robin Lindley: Congratulations Mr. Davis on your groundbreaking book The Brain Defense. What inspired your new book on neuroscience and criminal law? Did it grow out of your research for your previous books and articles on criminal justice issues?

Kevin Davis: Thank you, Robin, that’s very kind.

The short answer is curiosity. But a little background might be helpful. I was a crime reporter for many years at a daily newspaper, and later covered the criminal justice system as a magazine writer where I could explore issues in greater depth. I’ve seen all manner of violent and destructive behavior that people are capable of, and always wanted to better understand the underlying causes of violence.

In Chicago, while working on my last book, Defending the Damned, I sat in murder trials where lawyers tried to humanize clients for doing inhuman things. And they often did this by claiming their clients were damaged in some way. It might be abusive childhoods, poverty, alcohol or drug abuse. Even brain injuries. And in many cases, those claims were persuasive, offering some explanation of how these criminals came to be who they were, but not necessarily excusing them for what they did. Some deserved compassionate sentences and mental health treatment, or life sentences instead of death.

That said, The Brain Defense came about by accident, but was born of my interest in these issues.

After former Congresswoman Gabby Giffords survived as assassination attempt in 2011, I became curious how people recover from traumatic brain injuries. I wondered whether she could ever return to being the person she was before the shooting. So, I began researching brain injuries. I interviewed a cousin of mine, Dr. Elliot Roth, a top specialist who works with patients recovering from stroke and other brain injuries at the Rehabilitation Institute of Chicago. He offered me some fascinating insights about traumatic brain injuries. I also spent time visiting a place called the Brain Injury Clubhouse in Chicago, which offers services and counseling to those seeking to re-learn many of the most basic aspects of living life. Many of them also had personal and legal troubles, and some of them had become violent.

So as I dove deeper into this world, I came across articles about the intersection of law and neuroscience, which led me to the MacArthur Foundation Research Network on Law and Neuroscience, which had been examining how neuroscience is being used or misused in the courtroom. I had never heard of it before, and was fascinated by its work. As soon as I started poking around in this area, I was hooked. I had found a subject that melded my interests in the criminal justice system, science and human behavior.

Robin Lindley: What was your research process for exploring the emerging area of what some call “neurolaw”—the intersection of neuroscience and law? Where do you begin with such a complex topic? How did your book evolve as you pursued your research?

Kevin Davis: The MacArthur Foundation Research Network was a great place to start with its wealth of published papers and experts willing to be interviewed about the subject. Not long after I began researching my book, the organization had scheduled a law and neuroscience conference in Chicago, where I live, and I asked whether I could attend. I met a number of prominent people in the field, which opened many doors for me.

I also was able to land a fellowship at the University of Pennsylvania, which offered a program called Neuroscience Boot Camp. For ten days, some of the university’s top professors in the field ran mini courses and seminars for a group of lay people from around the country, including business managers, lawyers, journalists, marketing professionals – anyone who was interested in better understanding the brain and human behavior. The experience was invaluable and lots of fun.

Robin Lindley: You mention some statistics on the growing use of “the brain defense” in criminal cases. What did you learn about the frequency of the use of neuroscientific evidence presented in criminal judicial proceedings?

Kevin Davis: I found that it’s a growing phenomenon. Nita Farahany at Duke University has done a couple of studies to document this. She found that nearly 1,600 judicial opinions issued in U.S. courts between 2005 and 2012 mention the use of neurobiological evidence, such as images of a person’s brain structure, its level of functioning or presence of abnormalities. In 2012, there were more than 250 opinions issued in which defendants argued, in effect, that their “brains made them do it.” That was more than double the number five years earlier.

Farahany recently completed collecting new data on this phenomenon when I interviewed her last summer. Her preliminary figures indicate that use of the brain defense has doubled to about 400-500 per year since her last study and she told me it’s a trend that’s not going away.

Robin Lindley: What surprised you as you researched and wrote about the law and the use of neuroscience?

Kevin Davis: The research for this book was a constant journey of discovery and part of the fun. I found connections among people, stories and history that I had never known. For example, I had never heard the story of William Freeman, a man of African and Native American descent who was arrested for killing a white family in 1846. Freeman was represented by William Seward, who later became President Lincoln’s secretary of state. The Freeman case is believed to be one of the first insanity defenses in this country. It’s a compelling story about law, race and the effects of traumatic brain injury on human behavior. Seward risked everything by representing a black man arrested for killing a white family during a very volatile time in our nation’s history. As I researched the book, I also learned of an attorney in Florida who routinely asks to scan every one of this clients’ brains, which he uses to try to get them treatment instead of prison.

Robin Lindley: A graduate student who you talked with about law and neuroscience said that “we are a society of neurological constructs.” What do you think he was getting at?

Kevin Davis: That was a pretty deep statement. I think, like many neuroscientists, he has a way of reducing human behavior, thought and actions into the physical and biological. Our very beings, he seems to suggest, are born from the electrical and chemical reactions that occur in our brains.

Robin Lindley: In your book, you focus on the 1991 case of Herbert Weinstein. He murdered his wife and never denied the crime. How did his lawyer decide to offer evidence of brain damage to explain Weinstein’s seemingly impulsive and uncharacteristic homicidal act?

Kevin Davis: Weinstein’s lawyer, Diarmuid White, was struck by how Weinstein seemed so cool and detached from the gravity of being charged with murder, as well as the tragic death of his wife, who he really loved deeply. This suggested to White that something must be wrong with Weinstein, and he sent him for psychiatric tests and eventually an MRI, which revealed that Weinstein had a cyst the size of an orange growing over his left frontal lobe. White, thinking like a good lawyer, pursued this as a possible explanation, and defense, for Weinstein. So he set about learning about brain damage and behavioral changes of which there is a long, documented history, going back to the famous case of Phineas Gage. Gage was a railroad worker in the 1840s who survived a horrible injury after a tamping iron shot through his skull. Gage suffered severe changes in his personality afterward, and his case opened the doors for understanding the effects of brain injuries on personality and behavior.

White spent time digging into research about brain damage and personality changes. The Weinstein case, which began in 1991, was long before the era of Google where you can simply type search terms and find research papers about brain damage and behavior, the use of PET scans and so forth. White did his research, with some help, the old fashioned way, by going to libraries, poring through medical journals and textbooks and educating himself in this new world.

Robin Lindley: How did the Weinstein case become a turning point in the use of neuroscience in American courtrooms?

Kevin Davis: The Weinstein case was the first time that a defense attorney presented brain scan evidence in what’s known as the guilt phase of a trial. Brain scans had been used in hearings for people facing the death penalty as a way persuade judges and juries that the defendants might be spared from death because of brain damage. They’ve also appeared in mental competency hearings. The Weinstein case evolved into a contentious battle over whether brain scan evidence should even be admitted in court.

Robin Lindley: Why didn’t evidence of brain damage and other neuroscience evidence have a prominent role in criminal cases before the Weinstein case? Certainly, images of damaged brains were available for decades before 1991. Were there advances in law and medical technology by then that paved the way for use of this evidence in the Weinstein case?

Kevin Davis: I think the advances helped, but also the greater acceptance in the scientific community that PET scans were an important and accurate diagnostic tool. Another reason is that the Weinstein case was relatively high profile. The day after Weinstein killed his wife, the New York Daily News had a front-page story with the headline “Hi-Rise Horror.” The story was covered in the New York Times, and even USA Today had a short item about it after the case was over. So I think publicity about it put this idea in more lawyers’ brains, so to speak. But also, the fact that the judge allowed the evidence in opened doors that were previously closed.

Robin Lindley: I appreciated your history of some famous cases of brain injury, such as the terrible brain injury that Phineas Gage survived in the 1800’s. What did scientists learn from such cases about the brain in terms of cognitive compromise and other damage?

Kevin Davis: The Gage case, of course, is among the most well-known and famous in the world of neuroscience. Phineas Gage was a railroad worker in Vermont in 1848. He set off a spark while preparing an explosive charge with a tamping iron about three feet long and two inches in diameter. The rod shot through his left eye and into his skull and went through his brain and landed several feet away. What made his case significant was that his personality was said to have radically changed afterward – from being congenial to erratic and rude. His doctor said Gage had become “fitful, irreverent and grossly profane.” And that “Gage was no longer Gage.”

Since then, it’s been widely accepted in medical and neuroscientific communities that the change in Gage’s behavior was tied to the damage in his prefrontal cortex. This was an important discovery about localized brain function. The case was thought to be the first to suggest that an injury to the frontal lobe can compromise reasoning and regard for other human beings.

Contemporary research supports the theory that the prefrontal cortex is the area of the brain responsible for rationality, morality, and intellect. So from this sprang the idea that if people sustained brain damage, particularly in the frontal lobe, they might experience personality changes.

Robin Lindley: And, in 1966, the Texas Tower sniper, Charles Whitman, complained of psychological problems before his horrific shooting spree that left 16 dead and 31 wounded. He requested an autopsy in a suicide letter. What did scientists learn from posthumous studies of Whitman’s brain?

Kevin Davis: It turned out that Whitman had a small brain tumor about the size of a pecan. The growth was nestled beneath the thalamus, which relays sensory and motor information and regulates sleep, and was pressing on the amygdala, a part of the brain associated with emotional regulation and behavior. The doctor reported that he didn’t think the tumor was related in any way to Whitman’s psychiatric complaints or headaches, and certainly not to his homicidal rampage. Yet many of Whitman’s surviving family members and friends wanted to believe that the tumor was somehow responsible for his actions, just as the bomb threat suspect’s parents believe.

A state commission, called by Governor John Connally, left open the possibility that the tumor played some part in Whitman’s behavior, but did not say it caused his murder spree. The committee noted that abnormal aggressive behavior might be a manifestation of organic brain disease but also said it could not establish, with any clarity, the relationship between the tumor and Whitman’s actions. The care and planning that Whitman had taken in preparation for his killing demonstrated that he had forethought and knowledge of his actions and he most likely would not have fit the legal definition of insanity.

Robin Lindley: You detail the evolution of the insanity defense. What are a few things your readers should understand about the insanity defense, criminal responsibility, and how neuroscience may play a role in establishing that defense today?

Kevin Davis: The insanity defense, is generally reserved for people who truly suffer debilitating mental illness or psychiatric disorders so profound that they cannot tell the difference between right or wrong or appreciate the nature of their actions. It’s a very difficult defense to prove, is rarely used, and when it is used, it rarely succeeds. It’s known as an affirmative defense, which means that the burden of proof has shifted to the defense lawyer to prove the client is insane.

After John Hinckley Jr., was found not guilty by reason of insanity for his assassination attempt on President Ronald Reagan in 1981, many states changed their laws to give jurors the option to render a verdict of guilty but mentally ill, which would acknowledge that defendants can have mental health problems but are not absolved of responsibility. Under this model, those found guilty are required to receive psychiatric treatment in prison or treatment in a secure mental health facility until they are well enough to serve the remainder of their sentences in prison.

Criminal defendants who invoke a so-called brain defense are generally well functioning people who understand right from wrong and would not fit the definition of insane (though some have tried an insanity defense). They’re claiming that brain damage has contributed to brain dysfunctions that impair their judgment and impulse control.

Robin Lindley: Is there a consensus among neuroscientists on the use of medical evidence to establish either insanity or mitigating circumstances in sentencing of criminal defendants?

Kevin Davis: Neuroscientists would agree that you can’t prove insanity with brain scans. The best you can offer with a brain scan is to show brain dysfunction, which may or may not lead to behavioral problems and mental health issues. At best, the brain scans might be used to support a traditional psychiatric diagnosis based on observed behavior and questioning patients about their symptoms.

And neuroscientists are cautious about using this evidence because while studies have shown damage to certain parts of the brain can cause aggressive or impulsive behavior, others who have sustained similar brain damage do not exhibit these behaviors. You simply make a generalization like that. The other matter is that you can’t really take data drawn from large groups of people and tie it to a specific person or case.

Robin Lindley: Have prosecutors used seemingly normal neuroscience findings to challenge the so-called “brain defense”?

Kevin Davis: Prosecutors certainly line up their own expert witnesses who challenge the defense witnesses over the value and meaning of brain scans and brain studies. The most common argument against the brain defense is that you can’t apply generalizations about groups of people to individuals, and that no everyone with a brain injury becomes a criminal.

Robin Lindley: You carefully describe brain development and the limitations of the immature juvenile brain for cognitive tasks such as decision making and judgment. What has neuroscience revealed about the younger brain and how are courts responding?

Kevin Davis: Thanks to neuroscience, researchers have a better understanding of adolescent brain development and its role in decision making and impulsive behavior. These new insights have led the courts to reconsider how to handle young offenders. It’s also influenced how the courts determine the extent of their culpability, and whether they have the capacity to become better people as their brains become fully mature. The research confirms that young people simply don’t have the tools yet to always make sound judgments or control their impulsive behavior.

Neuroscience has revealed that brains are not fully developed until a person is about 25 years old, that information, along with other studies of adolescent brain function, were taken into consideration when the U.S. Supreme Court ended the juvenile death penalty, as well as mandatory life without parole for juvenile offenders.

We also know that many things can go wrong as young brains develop, which can lead to psychiatric and behavioral disorders. Stress can inhibit proper brain development. Abuse, neglect and mistreatment can alter brain function and affect mental, emotional, and behavioral development.

Robin Lindley: You write in some detail about the recent interest in chronic traumatic encephalopathy (CTE) as seen in people such as football players who receive multiple blows to the head, and traumatic brain injury (TBI) as seen in soldiers who suffer blast injuries. What are a few things you learned about these conditions and how evidence of such trauma may be used in criminal proceedings?

Kevin Davis: Many retired football players believe they suffer from chronic, progressive brain damage – a condition known as Chronic Traumatic Encephalopathy, or CTE. Years of head collisions apparently have taken a profound toll. CTE has been associated with psychiatric symptoms, including depression and even suicidal behavior. Several players who have been arrested on charges of domestic violence have suggested that CTE contributed to their behavior. But researchers differ on whether there are indeed causal relationships between CTE and aggressive or criminal behavior – or whether it’s another form of the brain defense. For one thing, CTE cannot be diagnosed in a living person. Only though a post mortem examination of the brain can the presence of the disease be confirmed. So legally, it would just be a theory that the person had CTE. Also, football players by nature play an aggressive sport, and prosecutors could argue that their aggression off the field may not be so unusual.

Combat veterans also have been coming home with depression and changes in personality—behavior that can be linked to both post-traumatic stress disorder as well as traumatic brain injuries. TBIs were the invisible wounds of the war because soldiers didn’t necessarily have to be struck by bomb shrapnel to get injured. They were injured indirectly as a result of being in the vicinity of blasts, most often from improvised explosive devices. A sudden jerk of the head, along with the blast pressure, can cause shearing within the brain, tearing arteries, veins, connective tissue and nerve fibers.

There are many instances of combat veterans getting in trouble back home and attributing their problems, in part, to those injuries. On the other hand, many more soldiers returned with brain injuries and PTSD who never became violent, so it’s difficult to navigate this. Still courts, particular veteran’s courts, are showing some compassion and understanding for those vets who need treatment and counseling.

Robin Lindley: Your book is primarily concerned with criminal cases, but I wondered what you’ve learned about the use of neuroscience in civil cases such as personal injury matters and other issues? Is there increasing use of evidence of brain function in civil courts?

Kevin Davis: While this is not my area of expertise, I have come across many instances in which personal injury lawyers turn to neuroscience in assessing damages for their clients. Many people suffer from traumatic brain injuries in car accidents, on the job accidents and from other causes. Brain images can be used to document these injuries and also show how well or how poorly a person’s brain may be functioning, which can be helpful in determining the need for future care and subsequent costs.

Robin Lindley: Did you or the experts you spoke with see problems in the way that attorneys communicate about the complicated science on the brain and behavior?

Kevin Davis: Experts are always concerned that lawyers will oversimplify or mischaracterize the science. Lawyers also tend to use visual aids that seem to connect with juries. There is a case I describe in my book about a jury that decides to sentence a convicted killer to life instead of death because, as one juror put it, she was swayed by the fancy brain images she saw in court.

Robin Lindley: Where are the courts today in the use of neuroscientific evidence? Is this evidence accepted generally, or do you see marked differences in use of this evidence between jurisdictions?

Kevin Davis: PET scans and fMRI cans are generally accepted as valid methods for measuring certain types of brain activity and are routinely admitted as evidence in death penalty sentencing hearings. The battles continue, however, over interpretation of those images and whether you can tie brain activity, or lack of brain activity to certain behavioral patterns or actions.

Robin Lindley: How can neuroscience help in determining offender responsibility?

Kevin Davis: It can’t determine whether someone is responsible for committing a crime. It can, however, be used to support traditional medical diagnosis of psychiatric or mental health problems. Some scientists have found certain patterns in the brains of schizophrenics or psychopaths, for example. The images alone don’t prove anything but can support certain observable behavior and other methods of testing for such conditions.

Robin Lindley: Some scientists you interviewed argue that neuroscience has virtually no role in the courtroom but can be used to improve the criminal justice system and social policy. What are some ways neuroscience can advance reform and social justice policies?

Kevin Davis: It’s already had an impact on the juvenile justice system where juveniles no longer can be sentenced to death, nor get mandatory life without parole. There are also neuroscientists who are examining decision making and punishment that can help inform how judges and juries deal with such questions.

Neuroscientist David Eagleman is working on a proposal to create what he calls an evidence based, forward looking legal system to address mass incarceration and the criminalization of the mentally ill. His idea it to build a system that accounts for people’s individual characteristics rather than imposing prescribed sentences. He’s also working on programs to help people control their impulses through a biofeedback style exercises, something he calls the “prefrontal workout.”

Other researchers are seeking to learn what areas of the brain are engaged when we make decisions to punish others and how we hold them responsible, which may be useful for judges and juries.

Robin Lindley: Is there anything else you’d like to add for your readers about how neuroscience has transformed law, or any issues that have come up since the book appeared? Are you working on another book now?

Kevin Davis: I recently read a fascinating and tragic story about a beloved school librarian from New York who suddenly began to suffer serious mental health problems because of an undiagnosed brain disease. His personality completely changed and his career ended after he was charged with an inappropriate encounter with a female student. His marriage collapsed and he spent his savings on some kind of online banking scam. It turned out he had type of frontotemporal dementia, which was confirmed after his death. No one had suspected or diagnosed it.

I think we’re going to see more about how the law and society deals with people suffering from this kind of unusual disease, as well as early dementia, stroke or other brain conditions that can shift their personalities and create a host of personal and legal problems. This area fascinates me, and I may dig into it further. I’m also quite interested in continuing to investigate the flaws within our criminal justice system.

Robin Lindley: Thank you for sharing your thoughtful insights Mr. Davis. And again, congratulations on your vivid and provocative new book, The Brain Defense.

Kevin Davis: Thank you. It’s been a pleasure.