Deven Black was a suburban father, husband, and well-respected librarian who worked for New York City public schools. Then, in 2013, he was investigated for calling one of his female students “sexy.” Shortly after, he began to send thousands of dollars to “friends” he made online in Ghana and Nigeria, and was caught depositing fraudulent checks, baffling his wife and family.
In 2015, just two years after accepting an award for school librarian of the year, he was under arrest at a Bronx jail. Broke and estranged from his loved ones, he was murdered in January 2016 in an altercation at a homeless shelter.
How did Deven Black’s life spiral out of control? A year after his death, testing of his brain showed that he suffered from frontotemporal dementia, the name for a cluster of disorders that can affect the frontal and temporal lobes, areas associated with personality, decision-making, language and self-control. When a brain has frontotemporal degeneration, like Black’s did, it can lead to extreme behavioral changes including sexual proclivity, criminal activity, and more.
“It’s cases like [Black’s] that make you want to recognize this problem, and try and see if there’s a way to intervene before it gets to that point,” says Ryan Darby, a neurologist at Vanderbilt University Medical Center who regularly treats people with frontal lobe disorders. “These patients often end up in the criminal justice system instead of seeing a neurologist first. When I started seeing them, I realized we didn’t have a good enough understanding of what the neurobiology behind this is.”
There are other well-known examples of people suffering from brain abnormalities that, seemingly, led to crime. In his autopsy, the 1966 Texas tower shooter, Charles Whitman, was found to have a brain tumor. In 2000, a schoolteacher from Virginia was unable to resist his urges for child pornography and eventually sexually assaulted his teenage stepdaughter. Later, doctors found a right orbitofrontal tumor. When it was removed, his urges went away.
For Darby, these tragic cases offer not only an opportunity to help his patients before they end up in jail, but a chance to gain insight into the neurobiological correlates of “criminality.” In a study published last month in PNAS, Darby and collaborators examined 17 past incidents in which brain lesions, or damage, were associated with criminal behavior. In most cases, the person had not exhibited any criminal behavior before the lesion, only after. By seeing where the lesions were in the brain, Darby and his team implicated a brain network that included the medial prefrontal cortex, orbitofrontal cortex, and different locations within the bilateral temporal lobes. These areas overlap strongly with areas previously associated with moral decision making, Darby says, so their potential link to criminality makes sense.
His co-author Michael Fox, a neurologist at Harvard Medical School has done similar work mapping networks for hallucinations and capgras syndrome, which is when a person thinks people around them are "imposters." He says that creating a network is one step beyond identifying a single brain region correlated to a certain behavior. It leads to a better understanding of why damage in many areas can cause similar problems, by seeing what changes or interruptions it’s causing in the brain overall.
But both Fox and Darby tell me that their findings aren’t ready to be applied in the courtroom just yet, despite their desire to intervene in cases like Black's. “We don’t know the actual risk of: If you have a brain lesion in one of these regions, how likely are you to commit a crime,” Darby says. “It’s certainly not a one-to-one link, which would be the most useful for the legal side, but unfortunately life is usually not that easy to parse out.”
He means that a person could have a brain lesion in their network and never commit a crime. And, of course, a person without lesions could commit a crime, unrelated to brain damage. Still, Darby thinks there’s a potential, one day, to be able to use this network to look for functional abnormalities in people, even without damage, to ask if someone is predisposed for criminal behavior.
This kind of study often leads to a vision of our criminal justice system’s future, when scanning someone’s brain can immediately tell us if they’re guilty or innocent. (Whether that's viewed as dystopian or utopian is up for debate.) Darby and Fox see their study as only a foray into the ways brain networks may one day be used to adjudicate criminal behaviors in court, but the truth is, neuroscience has already entered our courtrooms in this way.
Despite a worry that fMRI lie detection or EEG “mind reading” will swoop in and upend the justice system, the actual neuroscience being presented as evidence is much subtler, and is making an impact in all stages of the criminal justice process.
For cases like Black’s and others with frontotemporal dementia, Darby thinks that neuroscience should be there to help, based on how repeatable and predictable the behaviors associated with the disorder are. But what about a person without frontotemporal dementia, who had a brain injury ten years ago? Does that person have enough damage to their brain to make them innocent? What about to get a lighter sentence? To determine their ability to stand trial? In the Virginia case, was the man guilty of pedophilia or was it his tumor?
These questions are playing out in our courtrooms every day, whether or not the science is ready to answer them, and the number of cases involving neurobiological evidence and arguments are growing each year.
“There’s no solution to any of these problems right now,” Fox says. “Those are much bigger questions that I don’t know that neuroscience alone can answer.”
To learn exactly what the current role of neuroscience in our courts is, I called up the only person systematically keeping an eye on it: Nita Farahany, a law professor at Duke University. She and her law students have created a database to track when neurobiological evidence is mentioned in judicial opinions. They include the mention of any medical history of past head injuries or brain damage, any neuropsychological testing, and brain scans.
According to her records, there were more than 1,585 opinions between 2005 and 2012 that mentioned the use of neurobiological evidence by criminal defendants to argue their case. In 2012 alone, there were more than 250 judicial opinions (more than double the number in 2007) that said defendants argued that their “brains made them do it,” Farahany wrote in a review paper. And the criminal cases in her database are potentially just the tip of the iceberg, she says, since 90 percent of criminal cases don’t go to trial, and she doesn’t have those records.
Not only did the amount of cases increase, she found their level of scientific detail did too. Farahany says that earlier, neurobiological evidence was referred to as “part of a laundry list” of other kinds of scientific evidence, but now “judges spilled substantial ink discussing the neurobiological evidence often in significant detail and with citations to scientific literature and the experts who testified in the case.”
The arguments that neurobiology made a defendant act against their will are actually still relatively uncommon and unsuccessful, she says, despite that being a big concern amongst neuroscientists and other academics. Instead, Farahany laid out where this neurobiology is really being put to use: “Pre-trial, to determine if someone is competent to stand trial,” she says. “During the trial to determine if someone is innocent or guilty. And for determining sentences—to decide the degree of culpability [and the extent to which] you actually punish a person who's been convicted of a crime.”
There’s a misconception that it’s primarily brain scans being used, but she says that only about 15 percent of the cases had scans mentioned in the opinions. Scholars also presume that neurobiology is being predominantly used in capital cases. But in her sample, only 40 percent of the cases were capital; the other 60 percent were serious felony cases, like drug possession, trafficking, violent assaults, robbery, fraud and more. For capital cases, she’s found that about 5 percent of all murder trials and 25 percent of death penalty trials involved criminal defendants asking for lower responsibility or lighter punishment using neurobiological materials.
“It’s rare, if not almost never, that neuroscience takes a person who has killed somebody from the category of first degree murder to not guilty,” Farahany says. “But it does decrease the extent to which they’re found guilty....And that happens in quite a few cases.”
Taken all together, Farahany estimates that neurobiological evidence is introduced in at least 5 to 6 percent of murder trials in the USA, and 1 to 4 percent of other felony offenses.
So what does this look like in action? Some examples from Farahany's case files: In 2007, 17-year-old Miguel Angel Ruiz was charged with murdering his mother. Two neuropsychologists gave testimony after examining him. One said that Ruiz had “a severe language disorder that arose from an organic brain-processing deficit that interfered with his language skills.” This would cause an “inability to converse, explain, or impart information,” all necessary to assist in his own defense. The other expert confirmed that Ruiz had a developmental language disorder, and said that “the left part of his brain, which deals with language skills, did not develop as well as the right part of the brain, which deals with nonverbal skills.” Though a previous jury had found Ruiz competent to stand trial, the testimony of the two experts changed a judge’s mind, who overturned that jury's decision.
In other cases, the reverse can happen: MRI or neuropsychological exams have been used to show that someone is faking their lack of competency, and have caused judges and juries to continue, instead of stop, the proceedings. And sometimes when neurological evidence is used in pretrial, like with Ruiz, it can work against them in sentencing. "A prosecutor will use that same evidence to say this person is admitting they are programmed to be a violent offender, and you should lock them up and keep them away from society,” Farahany says.
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Sentencing is where a large bulk of neurobiology is being applied; Farahany found that about 44 percent of neurobiological claims raised were attempts to lighten a sentence. But almost half of those claims didn’t just refer to brain evidence; they tried to argue during the appeals process that they received ineffective counsel because their lawyer didn’t introduce neurobiological evidence at their sentencing.
In one such case Farahany describes, a defendant and a coworker picked up a woman walking down the side of the road, after drinking at a bar. One of the defendants pulled a knife on her, sexually assaulted her, slit her throat and stabbed her over 30 times, then left her body in the Arizona desert. He was convicted by a jury of first-degree murder and sentenced to death. During his appeal, he presented evidence that he had brain damage and neuropsychological deficits. The court found a “reasonable probability” that the defendant might have gotten a lesser sentence had the court had that information, and found trial counsel ineffective, and so the defendant got a new trial.
“Such rulings put neurobiological evidence in a rarified position of must-investigate evidence,” Farahany notes. “Defense counsel are ineffective if they fail to mount a defense at all, sleep through an entire (but not just parts of) a trial, or if they fail to investigate a probable neurological abnormality in a defendant. One of these things is not like the others, and its oddity makes clear that neurobiological evidence is an embedded part of the criminal process.”
Still, between 20 and 30 percent of defendants have some success on appeals partially because of neurobiological evidence, in capital cases and non-capital cases alike. When Farahany compared the reversal rates in those cases versus all criminal appellate cases, the reversal rate in cases with neurobiological evidence is higher.
These examples show that neuroscience isn't being used, in most cases, to completely free someone of blame, but rather, to bolster arguments for sentencing, ineffective counsel, mental states, and more.
But there are some researchers who think despite the subtleties in the uses of neurobiological evidence, none of it is appropriate. Not because a neurophysical exam isn't capable of determining mental state, but because of how such evidence might impact a jury. Deena Weisberg, a cognitive psychologist at the University of Pennsylvania has been studying what she calls the “seductive” appeal of neuroscientific evidence for more than ten years.
She’s done studies that show that if you add irrelevant neuroscience language to explanations of traits or behavior, even when the explanation is a poor one, people find the argument more convincing. “People think there’s some kind of seductive allure of these neuroscience details that really makes them believe in the explanation more when it references the brain,” she says. Other work has had similar findings.
“What I hear from my participants are things like, it sounds more scientific,” she says. “Or, it sounds more serious. That there’s something more persuasive or believable about it.”
She thinks that the jury's response show a misinterpretation of what brain abnormalities really mean. Everything influences the brain, she says. And relegating a criminal act to just a feature of the brain isn’t how people work. “People have this tendency to be dualist, and to think that your brain is something separate from you, and who you are, and what you’ve done and what you’ve experienced,” she says. “But, that’s false. Everything changes your brain. It has to."
Nick Schweitzer, a psychologist and professor at Arizona State University, has also looked in detail at how neuroscientific information affects juries. His work didn't, at first, find an overwhelming effect of brain evidence. Schweitzer says that juries intially don’t know what to make of it. But when he exposed people to two scenarios, one with and one without neuroscience, “Now, all of a sudden, they do tend to strongly prefer neuroscience,” he says. “This applies to a court case where you have an expert who has a brain image, and you have another expert who does not have a brain image; [the jury] is going to side with the one with the brain image."
Even with those caveats, Weisberg doesn’t think it’s responsible for this kind of evidence to be used, especially as Farahany shows the number of cases with neuroscience increasing. She thinks it’s easier for researchers to understand neuroscience's potential caveats, she says. But in court, those easily get ignored.
“I know enough about how poorly people think about science to know that they’re going to gloss right over all of the important subtleties,” she says. “That this [evidence] is a predisposition to something, or this means that you’re at a higher risk of something. And that doesn’t mean that you’re ever going to do anything. I think that there isn’t a good way to try and frame that for juries at the moment that would really help them make the science clear enough to make it helpful.”
Farahany thinks there’s no point in trying to ban the use of neuroscience in our courtrooms, because it’s already widely being used, and probably not going away. Attempting to stem the flow of neurobiological information is “futile and counterproductive,” she writes, because “neuroscience is already entrenched in the US legal system.”
Her database doesn't exist to condemn the use of neurobiology, but to give us a way to track it and make sure academics know what's going on and can be part of the conversation. She thinks that when it’s used to improve medical diagnoses or determine competency, it can be beneficial. “Where I don’t think it tells us very much," she says, "Is when it’s used to try to inform the extent to which a person is guilty of committing a crime.
Fox and Darby hope that their study and others like it could one day weed out some of the cases that “cry brain” as an excuse for defendants. It could possibly give lawyers a more defined network of which brain abnormalities are most likely linked to criminal behavior. But as we gain a better understanding of the biological underpinnings of behavior, the applications could get more complex, not easier. “It’s only a matter of time before we begin to see all criminal behavior and all behavior for that matter, in this way,” Fox says. “That there are brain abnormalities that predispose to every behavior.”
Then, it’s up to us to decide what the function of the law is, says Hank Greely, a lawyer and professor at Stanford University who has been studying the ethical, legal and social issues that arise from science for 25 years. He asks me (hypothetically, I hope): Is criminal law just about punishing people for doing bad things? Or is it about deterring them and deterring others? Is its purpose to lock them up so they can’t hurt other people? Or is it to rehabilitate? Is it really that different if your behavior was caused by a brain tumor, or caused by being raised in a very bad family, with drug-addicted absent parents? People don’t have a choice about that either.
There are different functions of criminal law, and finding who is at “fault” is just one strand, even if the neuroscience did reach the point of determining that. “We as a society need to use the new knowledge we’re getting from neuroscience appropriately,” Greely says. “Use it when it makes sense to use it, but not exaggerate its power, or underestimate its power. Right now, we’re at a stage where we’re more likely to exaggerate its power, because the science is still relatively new. The other mistake is equally bad. If we underestimate its power, and we miss out using neuroscience for something good, that’s a problem as well.”
Darby thinks there’s not an easy way to disentangle the responsibility questions, but echoes Greely in that it’s not ultimately a question that science answers. “I think the science can help us say what we can use as that criteria, how do we evaluate that in someone. But I think whether we should ultimately hold them responsible, that’s a question that we really have to decide as a society.”
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