The Brain Takes the Stand

By Isabella Cannava & Laura Mittelman

Art by Melody Fang & Yixin Jia


Exhibit A: The Brain

Prior to the year 2000, a 40-year old male school teacher from Virginia, whose name is unknown, was a functioning member of society and free of a criminal record [1]. However, this changed drastically when he suddenly began acting on pedophilic impulses. He was eventually convicted of child molestation after exhibiting a persistent pattern of this unlawful behavior. Upon his sentencing, however, he complained of debilitating headaches and was given a neurologic consultation. The brain scan revealed that he had a sizable tumor in the orbitofrontal cortex (OFC), an area of the brain that is largely involved in impulse control and decision making. Once the tumor was removed, his criminal behavior halted. A few months later, when he had returned to committing pedophilic crimes, it was discovered that the tumor had regrown in his OFC. Though the localization of the tumor in the OFC does not establish a direct causative mechanism for pedophilia, its growth correlates with his tendency to commit pedophilic crimes. After a thorough assessment it was established that the man may have already had preexisting pedophilic impulses that were aggravated by the disruption of the OFC, characterized by the lack of self-control and poor decision making [1]. The impact of the tumor on his actions points to the brain’s role as the driving force behind all of the behaviors that we exhibit. If you were a member of the jury during a court case that involved neuroscientific evidence, how would it affect your understanding of the crime?

Neurocriminology and neurolaw are emerging interdisciplinary fields that seek to apply our current knowledge of neurobiology to criminality, criminal justice, and the law [2]. The rapidly advancing field of neuroscience continues to expand our understanding of how biology and behavior are closely intertwined [2]. By harnessing knowledge about the complex mechanisms of the human brain, we can begin to understand the foundations of the diverse behavioral tendencies that humans exhibit and understand why people are who they are in a more grounded, biological way. The uniqueness of one’s brain connectivity can explain, for example, why certain individuals are more successful dancers and can move to the beat more fluidly, or why some individuals are more apt to help their communities and exhibit greater empathy [3,4]. Neuroscience inquiry expands far beyond these few examples and has infiltrated the study of criminal behavior because of its intricate, yet complicated, relationship with human civilization and practices.

By connecting the structure and function of certain brain regions to violent and criminal behavioral outcomes, we can better understand why individuals commit crimes and exhibit deviant behavior. As defined by the American Psychological Association Dictionary of Psychology, deviant behavior is behavior that deviates from the typical norms of a social group [5]. Thinking more critically about the definition of deviant behavior inevitably requires an acknowledgment of the structures of oppression that infiltrate society and greatly affect marginalized groups, such as people of color and people of lower socioeconomic backgrounds. This conversation is of utmost importance, especially when considering how neuroscientific evidence could hinder the development of a more fair and just establishment. The introduction of neuroscience in the courtroom must be handled with care and with mindfulness of people of color as well as those most affected by systemic racism. New technologies should serve to further break down barriers for individuals incarcerated at disproportionate rates. If used correctly, neuroscience in the courtroom has the propensity to maximize the profound possibilities of rehabilitation and more structured re-entry programs and ultimately aid in the progression towards ensuring equal justice, crime prevention, and criminal justice reform.

Is the Brain to Blame?

One of the first recorded cases of brain regions corresponding to specific personality traits and behaviors is Phineas Gage, a 25-year-old railroad construction worker who suffered a puncture through the left front of his brain by a one-meter-long railroad bar after an explosion on the tracks [6]. Phineas Gage had been a beloved community member and was described by those close to him as a kind, thoughtful, and soft gentleman [6]. However, shortly after the railroad incident, Gage’s pleasant demeanor was replaced by a highly antisocial personality characterized by violence, aggressive tendencies, verbal hostility, and disregard for the law. Gage’s transformation was so drastic that everyone around him claimed he “was no longer himself” [6,7]. Gage’s case is applicable to our discussion of neuroscience and crime due to his apparent inability to consider the consequences of his actions, unwillingness to accept constructive advice, and impulsive actions after his injury [6]. These behaviors are also present, alongside antisocial tendencies, in individuals with a higher propensity for committing crimes, further illustrating the brain’s impact on the likelihood to exhibit criminal behavior [7].

Moreover, Gage’s case study provides support for the theory that the brain is the biological basis of behavior and personality. The case highlights the localization of function, the idea that certain behaviors originate in specific brain regions which, if disrupted, produce predictable behavioral outcomes [6]. While Gage’s personality was drastically altered following his frontal lobe puncture, his short-term and long-term memories were still intact, along with his ability to understand and integrate complex ideas. Intrigued by the adverse personality effects of Gage’s frontal lobe injury, researchers began looking into how various disruptions to brain regions may manifest in criminals.

As early as the 1940s, scientists have utilized abnormal electroencephalography (EEG) scans, which detect electric signals in the brain, in an attempt to explain violent behavior [8]. Since then, neuroscientific understanding of behavior has evolved alongside the standards for admissibility of scientific evidence in the courtroom and is now used most commonly in criminal cases that begin as death penalty cases or involve a significant prison sentence [9].

Developments in the Law and the Brain

One of the first and most high-profile cases in the history of the United States where brain scans were introduced into the courtroom was John Hinckley’s attempted assassination of President Ronald Reagan in 1981 [10]. This case made use of a computed tomography (CT) scan, a combination of a series of X-ray images that produce cross-sectional renderings of the brain [10]. According to one defense radiologist, Hinckley’s brain appeared to be abnormally shrunken for his age [11]. Later in the trial, a leading researcher, who studied the connection between brain scans and schizophrenia, testified that the neural abnormalities seen in Hinckley’s brain were also commonly seen in patients with schizophrenia. After debate about whether or not the CT scan should be allowed to be used as evidence, the presiding judge decided that the scan may give the jury a clearer and more cohesive picture of the nature behind the crime [11]. Indeed, the inclusion and explanation of this neuroscientific evidence gave the jury a more comprehensive understanding of the crime, resulting in a verdict of not guilty by reason of insanity (NGRI) [10]. In 1984, after much public debate over Hinckley’s sentencing, President Ronald Reagan signed the Insanity Defense Reform Act, which outlined a more comprehensive approach to and stricter standards for the verdict of NGRI [12]. These standards included limiting the influence of expert testimony on legal issues and requiring a commitment proceeding if the verdict was reached, which requires the defendant to receive psychiatric treatment [12]. One of the core aspects of the NGRI defense that was not adjusted by Reagan and remains in use today is the M’Naghten test, which requires that the offender be unable to understand the criminality of their actions due to some mental complication [13].

During the Hinckley trial and up until 1993, the admissibility of scientific evidence in court was determined by the Frye standard [10]. The Frye standard states that in order for a scientific testimony to be admissible in trial, the method used must be “generally accepted” by the specific scientific community to which the method in question relates. Daubert v. Merrell Dow Pharmaceuticals, Inc. introduced a new standard dubbed the Daubert standard when two families sued the pharmaceutical company for birth defects of children whose mothers had taken one of their drugs during pregnancy [14]. The standards were changed to allow an expert to present scientific evidence as long as the methodology used to acquire it is testable, peer-reviewed, and accepted in the scientific community. The Daubert standard allows easier admissibility of scientific techniques that may not be widely used [10]. Neuroscientific evidence today must meet the Daubert standard to be acceptable in court. Although the standard allows for a larger variety of scientific techniques to be introduced in the courtroom, it does not guarantee admission of brain scans and still holds scientific evidence to strict standards.

By the late 20th century, neurocriminology began to look more closely at the implications of specific genes that are believed to predispose individuals to aggression and violence [15]. A significant amount of attention has been placed on the Monoamine Oxidase (MAO) gene, which normally encodes an enzyme responsible for breaking down the neurotransmitter serotonin, a brain chemical responsible for regulating mood and emotion. The breakdown of serotonin is depleted by the mutated gene (MAO-A), which causes high levels of the chemical to build up in the brain, which can ultimately lead to an increased likelihood of aggressive and criminal-like behavior including rebellion and hostility. The MAO-A gene was first shown to play a role in impulsive aggressiveness in a case study of a Dutch family in 1993, where each member exhibited similar abnormally hostile and violent behaviors They were all found to carry the same MAO-A gene. Since then, neurobiologists and neurocriminologists alike have taken a keen interest in further investigating this gene and its various mutations that might be implicated in an individual’s developing propensity to commit criminal acts. Through mouse models and pharmacological studies, researchers have gathered more evidence that the pathogenic pathways of MAO-A gene fail to produce the enzyme responsible for serotonin breakdown, exhibited by increased levels of serotonin in the brain associated with more prevalent aggressive behavior. Because of its clear correlation with hostility, the gene has earned its name as the “warrioror “criminalgene. Furthermore, the negative effects of the MAO-A gene can be exacerbated by external factors, such as early childhood abuse and trauma, leading to an increased propensity to commit acts of emotional violence later in life [15].

Individuals with the MAO-A gene also exhibit structural and functional abnormalities in the orbitofrontal cortex (OFC), the decision-making center of the frontal lobe of the brain, and the amygdala, a region outside of the prefrontal cortex responsible for emotional processing [7]. Researchers have observed that the MAO-A gene interferes with the proper functioning of the neural connection between the amygdala and the OFC, leading to emotionally-driven impulsive and aggressive behaviors [15].

Further, as neurocriminology research advances, the smaller regions of the prefrontal cortex, called sub-cortices, are gaining more attention and are now considered to be the brain

regions most heavily associated with antisocial personalities [7]. Specifically, the ventromedial prefrontal cortex (VmPFC), the anterior cingulate cortex (ACC), and the OFC have been most closely studied in neurocriminological research of brain anatomy and function. The VmPFC is heavily involved in integrating the circuitries of various brain regions responsible for emotional processing, decision-making, memory, and social cognition [16], and the ACC plays a significant role in emotion processing and impulse control [7]. In addition to being affected by the MAO-A mutation, the OFC is a region that has also been consistently associated with the processes of learning from past mistakes, such as criminal behaviors, and adequately altering behaviors to avoid similar situations in the future [17].

Many specific cases have implicated lesions in the VmPFC and the ACC in the onset of recklessness and lack of remorse [7]. Moreover, these two brain regions are integral parts of the overarching intuitive and moral emotion processing networks in the brain. Deficits in these regions can heavily influence one’s tendency to engage in violent and antisocial impulses without the ability to consciously inhibit oneself [7]. In 43 imaging studies conducted on antisocial individuals, the vmPFC, ACC, and OFC were greatly reduced in size compared to controls, associated with the observed antisocial phenotypes [17]. However, when brought into the setting of the courtroom, it is crucial that a jury and judge understand that lesions in a defendant’s brain do not automatically explain their criminal behavior—brain scans of brain lesions do not express that the lesions caused the criminal activity, but simply that these injuries are known to be frequently correlated with criminal behavior and may aid the court in understanding the nature of the crime along with all of the other evidence [18]. This complex connection between neurobiology, genetics, and environment is a perfect example of how the interconnection between various variables is an important factor of neurocriminology and serves to possibly limit the influence neuroscience can have in the courtroom.

The Brains Behind Behavior

When discussing neural correlates of behavior and criminal propensity, it is always important to acknowledge that no one brain region is allocated explicitly to one function. While neurocriminologists are becoming increasingly more profound in their ability to map the areas of the brain implicated in criminal behavior, the field’s understanding of the brain’s complex, higher-level behavioral circuits is still limited. The brain communicates within itself to carry out complex behaviors, violence, and aggression. Understanding and possibly predicting propensity for crime presents a complicated task that requires multi-dimensional analysis of neurobiology. Until we understand the brain more concretely, it is not realistic that neurocriminologists will be able to apply the brain’s higher-level biological processes to the criminal justice system. The field of neurocriminology is beginning to break down these barriers to unlock the complex computations of the brain by looking more closely at the gray and white matter of various brain regions [19]. In addition, they are exploring the connections between areas across the brain that communicate via neural networks, some of which are thought to be designed for specific thought processes, such as decision-making or emotion processing [19].

As one can imagine, neural deficits in brain networks could be caused by many different factors, such as environmental influence during development, brain chemistry alterations resulting from drug use, physical injury to brain regions, neurodegeneration, and more. Currently, scientists believe the key to further understanding of brain function lies within the ratio of gray to white matter density in the brain, especially in the brain regions that influence one’s propensity to break the law [19]. The brain’s white matter consists of axons, the parts of the neuron that conduct electrical potentials to allow for electrochemical communication throughout the brain [20]. Gray matter mainly consists of cell bodies, which integrate incoming neural signals and other non-communication components of the human neurocellular system [20]. Differences in the ratio between gray and white matter in specific regions of the brain, such as areas critical for hostile behavior and impulse control, can ultimately interfere with the proper functioning of these regions and manifest as criminal behavioral tendencies [19]. A study examining gray matter density in the prefrontal cortices of murderers found depleted gray matter compared to non-violent criminalsInterestingly, this reduction spanned brain regions necessary for processing social cognition, strategic behavior control, and emotions [19]. The OFC, the decision-making region of the prefrontal cortex mentioned earlier as a key brain structure involved in Phineas Gage’s abnormal personality, has been shown to be fundamentally associated with one’s understanding of regretful behavior and future decision-making [19]. Therefore, reduced gray matter in the OFC can disrupt this neural process and increase one’s propensity to recommit crimes, rather than learn from past mistakes [19].

A common cause of reduced brain density is injury. Head trauma can significantly disrupt brain structure and alter the brain’s ability to perform certain cognitive functions, such as appropriately assessing situations and planning decisions that abide by external laws [19]. Furthermore, repeated minor traumatic brain injuries (TBIs) are known to have much greater and harsher health consequences, including a neurodegenerative disease called chronic traumatic encephalopathy (CTE). CTE research is still in its early stages, but the condition is characterized by the death of brain cells in regions associated with and including the prefrontal cortex [21]. Repeated minor TBIs contributing to CTE have been shown to induce the same neuropathology as seen in Alzheimer’s disease [21]. This novel finding is important because it directly links the detrimental long-term effects of TBI to the same pathogenic processes of better-known neurodegenerative diseases.

This correlation emphasizes the importance of considering TBI in court cases. Not only can repetitive brain injury lead to neurodegenerative disease, but given that TBI impacts the brain’s executive functioning, individuals suffering from the condition often experience impaired cognitive ability, therefore making tasks such as verbal reasoning, problem-solving, planning, sustaining attention, and dealing with new situations particularly difficult [22]. In criminals who have had a TBI, brain function involved in impulse control and empathy appear compromised [23].

The most frequently cited case of CTE in the criminal justice system is that of Aaron Hernandez, an American football player convicted of premeditative murder and sentenced to life in prison (he later died by suicide while in jail) [21]. Hernandez sustained innumerable physical attacks and blows to the head throughout his football career. Upon autopsy, pathologists found his brain to have extraordinarily similar characteristics to brains of individuals suffering from neurodegenerative diseases. His brain mass had physically decreased in size due to cell death. Interestingly, his vmPFC, the area partly responsible for emotional processing, decision-making, memory, and social cognition, was found to be so significantly reduced in size that doctors compared it to that of an Alzheimer’s patient, highlighting the high level of neuron cell death. This significant neurodegeneration in areas associated with higher-level reasoning provided insight into why Hernandez exhibited an absence of morality. In this case, these neurological observations were not enough to absolve him of wrongdoing [21].

Hernandez’s case highlights the ethical implications that neuroscience poses when applied to criminal justice. It raises the question: how will we ever find a fair medium where neuroscientific evidence in the courtroom can be both beneficial to the defendant and ethical in terms of the law? In cases of CTE, there is an apparent cause behind an individual’s increased propensity for criminal behavior, yet it remains debatable how reliable and influential such a neurobiological defense can be. If a violent offender has a brain injury, should that be taken into account in sentencing? In order to assess ethics, we must consider the individual’s conscious urge to commit a crime and their subconscious lack of inhibition and control. When considering neurological dysfunction as a result of TBI in the criminal justice system, it is imperative that we also consider how an individual’s socioeconomic or personal background could impact the number and scope of TBIs they sustained without even knowing. Research has shown that individuals with life histories of abuse, neglect, and trauma appear to be more likely to have a TBI versus those without such experiences [23]. Likewise, previous studies have revealed that head injuries are disproportionately experienced by incarcerated populations, estimating that the risk of such an injury is ten times greater within an incarcerated population compared to individuals from the general population [22]. As physical aggression and violence are particularly pervasive throughout the criminal justice system, repeated minor TBIs sustained in jail could have detrimental neurological consequences on inmates and pose yet another barrier in their journey towards successful reassimilation into society [24].

With these more recent scientific observations, it has become increasingly evident that something as complex as criminal behavior can not always be explained simply by correlating an abnormality in one brain structure to the behavior in question. The complications of neurocriminology are conserved when it comes to future possible applications in criminal justice.

Brain on Trial

Brain scans have introduced an unprecedented question in the courtroom: Where does the blame lie? Can someone identify their brain as an entity separate from themselves and argue that their criminal behavior was not their fault, but the fault of their brain? Alternatively, should someone be punished for neural differences out of their control? Neuroscientific evidence in the courtroom faces challenges related to demonstrating itself as useful evidence relevant to the case [25]. The 2005 People v. Goldstein trial is one example of a trial in which brain scans did not hold much weight [26]. In the case, the defendant was on trial for pushing a woman to her death in the subway. His defense introduced his brain scan into the courtroom in hopes of receiving an insanity plea due to a schizophrenia diagnosis [26]. In cases of insanity defense, the court requires that the accused is able to prove the absence of mens rea [25]. The term mens rea, which directly translates as “guilty mind” in Latin, refers to the presence of criminal intent and is understood through four criteria: acting purposely, knowingly, recklessly, and negligently [27]. These criteria require that one is unable to comprehend their actions, distinguish right from wrong, or feel that their action was propelled by an impulse beyond their control. In Goldstein’s case, the scans did not provide corroborating evidence to meet the criteria hence the court could not establish any causal relationships between the brain scan and his actions, maintaining that the evidence of the defense did not prove that he lacked mens rea [26]. In cases where a neurological or mental disorder may be involved, mens rea can be difficult to establish because the crime may have been a result of brain abnormalities and not motivated by pure criminal intent. In Goldstein’s case, the court excluded the brain scan from evidence since a schizophrenia diagnosis does not necessarily negate one’s mens rea, as one can still act knowingly with criminal intent [26].

While neuroscientific evidence was not sufficient in the Goldstein case, it played an integral role in the development of the Eighth Amendment, which prevents juvenile offenders from receiving the death penalty due to the acceptance of adolescent brain science [28]. In 2012, two 14-year-old boys were arrested for murder in two separate cases, Miller v. Alabama and Jackson v. Hobbs, and both were sentenced to life in prison. However, the United States

Supreme Court eventually overturned this decision, citing Roper v. Simmons, a 2005 case that decided that defendants may not be executed for crimes committed before the age of 18. While life without parole is a different sentence from the death penalty, it still ensures that the defendant dies in jail. After brain scans of juvenile offenders showing their developing adolescent brains were introduced into the courtroom in Roper v. Simmons, the United States Supreme Court found them to support that life sentences without the possibility of parole for juvenile offenders are unconstitutional [28]. This statement followed the neuroscientific evidence that showed that the development of neurons in the prefrontal cortex of juvenile brains is not complete until the early 20s, and could therefore result in decreased impulse control, bad decision making, and risk avoidance planning [26]. Similar to how Phineas Gage’s injury helped provide a deeper understanding of the connection between the prefrontal cortex and decision-making, moral reasoning, and other complex tasks, the court now recognized that incomplete development of the brain could lead to impairments in these areas [13].

Neuroscientific evidence and imagery in the courtroom can offer valuable insight into why individuals committed their crimes, which could contribute positively to personalized rehabilitative measures for those individuals. On the other hand, in cases of inhumane violent crimes such as murder, neuroscience in the courtroom could indirectly provide the opportunity for brain scans to be misused by lawyers and misinterpreted by juries and judges, resulting in unjust verdicts [29]. Just because there are connections between brain structure abnormalities and behaviors often associated with crime, does not mean that these brain abnormalities fully explain exhibited criminal behaviors [18]. Reaching a verdict is not a scientific conclusion, but one based on law that may or may not have been influenced by scientific evidence along with the other facts of the case [18]. If caution is not taken, the use of neuroscience in the courtroom can become precarious and may be manipulated in order to secure an inappropriate sentence or only aid those with the financial and social means to take advantage of it.


Apart from being leveraged in the courtroom in the interest of mitigating a defendant’s sentence, neurocriminology may also predict one’s propensity for committing a crime and reoffending, which is referred to as recidivating. Recidivism is an important concept in neurocriminology because it directly demonstrates how neurological abnormalities can affect the brain’s ability to learn from past mistakes and consider future consequences. Although behaviors and thought patterns stem from neural activity in the brain, the complex interactions between various other factors, encompassing all domains of science, cannot be ignored in the realm of neuroprediction either.

If we are able to distinguish areas in the brain that are related to criminal or deviant activity, perhaps we can use that knowledge to predict and prevent deviant behavior in the first place through a technique called neuroprediction. Currently, neuroprediction is being tested as a method of deciding the likelihood of recidivism [29-31]. In recent years, neuroprediction has begun to utilize algorithms and artificial intelligence to develop methods that can be completed by machines and calculate the risk of recidivism for an offender based on a series of factors that include neural activity [28,31].

Recidivism prediction relies on the analysis of behavioral risk factors based on dispositional, historical, contextual, and clinical variables. Together, these variables consider one’s family history, social networks, diagnosed mental disorders, and personal physical responses to certain triggers among other specifics [31]. Historically, recidivism prediction has used clinical expertise and statistical methods to anticipate the likelihood of someone to re-offend in order to inform decisions about bail, jail time, parole, and other aspects of criminal litigation [32]. The statistics-based approach to predicting recidivism, referred to as the actuarial approach, does not make predictions with complete accuracy, but its standardized methodology likely contributes to its increased effectiveness when compared to the clinical approach, which involves asking mental health providers to determine the propensity of a convicted criminal to reoffend [34]. Clinicians carry their own biases and approaches to diagnosis and may prioritize different factors than other clinicians, therefore increasing the subjectivity of the suggestion [34].

Despite the actuarial approach being more effective at predicting recidivism, concerns about the fairness of this technique have been raised. For example, many people are concerned about “moneyball sentencing” [32]. In 2002, the Oakland Athletics baseball team began using statistics to predict player performance, and after the team witnessed the method’s accuracy and utilized it to secure more victories, the technique was coined “moneyball” [35]. The use of statistics to make predictions gained popularity and made its way into the courtroom in the form of the actuarial approach. However, many argue that this method assigns a risk profile to an individual that is generalized from the social or economic groups they belong to. This is inherently problematic, as people have no control over the racial, ethnic, and socioeconomic groups into which they are born [35]. The precarious nature of the actuarial approach lies in the fact that it is unjust to punish someone simply for belonging to groups that have been associated with higher risks of crime. An example of the influence of the acturial approach leading to an unjust or “moneyball” sentencing occurred in 2016, when Duane Buck was convicted of capital murder and received a death penalty [36]. Although a psychologist testified that Buck was not likely to commit a similar act, he had noted that Buck was a Black man in his report and stated that this racial profile was statistically associated with increased probability of violent actions, therefore applying a group risk profile to a singular man. The jury decided on the death penalty. Buck recognized that the use of his race against him in a courtroom violated his right to an impartial jury. Yet, when he requested an appeal of his sentence based on bad legal counsel, Texas denied the appeal on the grounds that the inclusion of race did not sway the jury one way or the other. Once brought to the Supreme Court, however, the Court found the inclusion of race in this manner to be unconstitutional as without it the jury may have possessed reasonable doubt and perhaps would not have decided on a death penalty sentence. Buck was able to appeal his case and is now serving a life sentence instead of sitting on death row [36].

Even more recently, statistics have emerged that expose the relationship between increased law enforcement in non-white, lower-income communities and the higher rates of arrests among the individuals living there [37]. This statistical bias overflows into the courtroom when arrest rates among certain demographics are taken into consideration during sentencing. In an effort to combat this bias, there has been a burgeoning interest in the use of neural factors, like abnormal activity in the ACC, that may also function as predictive markers of deviant behavior and therefore may assist in neuroprediction of recidivism [38]. The inclusion of neuroscience into pre-existing prediction methods has also encouraged the development of machine learning techniques for and the integration of artificial intelligence (AI) into crime prediction [30]. One example of statistical methods being applied to brain imaging is multi-voxel pattern analysis (MVPA) [38,39]. MVPA analyzes functional magnetic resonance imaging (fMRI) data, which tracks the flow of oxygenated blood in the brain to indicate which areas are active. While fMRI data can be analyzed at one specific point in the brain, MVPA can take multiple points into account and identify a pattern in brain activity [40]. In relation to neuroprediction, MVPA can be used to evaluate an individual’s brain and identify known patterns in brain activity that may predict recidivism. The field of neurocriminology is developing alongside neuroprediction technology, so more extensive research is needed before specific biomarkers of deviant behavior can be identified and used in AI neuroprediction [30].

While research on biomarkers is developing, some recent studies have shown that incorporating brain-imaging data into AI risk assessment models results in more accurate predictions of recidivism [28,31]. In a study by Delfin et al. (2019), the blood flow to eight regions of the brain was measured in 44 forensic psychiatry patients. This data was added to an existing model of risk factors currently being used to predict recidivism, and the model’s accuracy increased from 64 percent to 82 percent [33]. While the application of artificial intelligence to the prediction of recidivism is exciting and provides new and interesting data, there are many challenges associated with the ethics and legality of its use [39,40]. It is important to recognize that while machine learning may reduce human bias, it does not automatically negate bias as a whole, especially because the algorithms are trained with

existing data which may already reflect human bias. For example, Correctional Offender Management Profiling for Alternative Software (COMPAS) is a widely-used risk factor algorithm that aids in sentencing based upon prediction of recidivism, but it was found to be incorrectly classifying Black defendants and women as high-risk demographics, wrongly predicting recidivism [39,40]. Delfin’s 2019 algorithm makes use of neurodata and is more accurate, but still includes behavioral risk factors like the ones used in COMPAS, demonstrating that algorithms that include neurodata are not automatically free of bias. Other concerns with neurodata are privacy and biological rights. While neurodata may be useful for predicting recidivism, it also may be useful for other purposes such as health insurance or job applications [30]. Even more concerning is the possibility for one’s neurodata to be used against them in a situation reminiscent of eugenics. Where would we draw the line with these privacy and biological concerns?

Brains For Good: Alternatives to Incarceration

Neuroscience may not currently be a primary method of defense or prosecution in the courtroom or an integral part of the recidivism prediction process, but its use in criminal cases has raised awareness about the mental health crisis occurring across the United States. While we are still learning about crime prediction measurements and methods, psychology and neuroscience are being implemented in criminal justice programs throughout the country to treat and support individuals who have committed crimes while living with a severe mental illness, such as major depressive disorder, bipolar disorder, and schizophrenia spectrum disorder [43]. Jail recidivism rates have shown significant decreases with the introduction of neuroscience research regarding mental health into the criminal justice sphere [44].

Based on a 2009 prevalence study of jails in Maryland and New York, 16.7 percent of inmates (14.5 percent of male inmates and 31.0 percent of female inmates) were determined to have a severe mental illness [43]. A more recent review from 2016 states that it would be reasonable to estimate that around 20 percent of all jail inmates are living with a mental illness [45]. This number is especially shocking when compared to the prevalence of severe mental illnesses in the general population, which the National Institute of Mental Health has estimated at 5.6 percent of all US adults [46]. On a national level, approximately 380,000 people living with a mental illness are incarcerated per day [44]. In 2016, it was reported that there were only about 20,000 total beds in civil state psychiatric facilities in the US, indicating that there are 19 times as many people with severe mental illnesses in jail than in treatment centers [43,46].

Steve Leifman, a county criminal court judge in Miami-Dade County, was appalled by these statistics and has since dedicated much of his professional career to shining light on the mental health crisis occurring within the country’s jail system. Leifman and his colleagues have developed the Eleventh Judicial Circuit Criminal Mental Health Project (CMHP), also known as the Miami Model for Jail Diversion [44]. The Miami Model consists of a two-fold approach to diverting offenders with mental illnesses from the jail system. The initial diversion tactic involves Crisis Intervention Team (CIT) training for law enforcement, which takes place before law enforcement officers respond to calls involving someone who may be struggling with a mental illness [44]. This tactic is based on the CIT training originally developed in Memphis, Tennessee in the late 1980s and aims to educate law enforcement officers on how to treat individuals with mental illnesses when responding to a call [48]. The second is a post-booking diversion tactic, involving an individualized treatment and check-in plan for the arrested individual, which is carried out after an official arrest record has been made. Once the CMHP identifies a person with a severe mental illness that has been arrested, they conduct an intensive screening process to determine the individual needs of the person, including assistance with mental health and substance abuse. If participants in the program willingly take part in and successfully complete their treatment plan, charges can be adjusted or dismissed completely [44].

After the initial implementation of the Miami Model in 2000, recidivism rates in Miami for people who have participated in the misdemeanor jail diversion program have decreased from 75 percent to 20 percent annually. Individuals from the felony jail diversion program have also seen more than a 75 percent reduction in rearrests [44]. Due to the success of programs like the Miami CMHP, we are able to develop a new understanding of the applicability of neuroscience and mental illness treatments in the criminal justice system. These models provide encouraging evidence that improved treatment of mental illness and neurological disorders can also decrease the number of people committing crimes and serving jail sentences. On top of that, people who are living with severe mental illnesses and do not have access to treatment are being treated with empathy and understanding, and are being given opportunities to heal, work, study, and thrive in today’s society. Developing the psychological and neuroscientific understanding of people with severe mental illnesses that commit crimes allows for the wonderful displays of humanity that are seen through programs such as the Criminal Mental Health Project.

The Verdict Is In

Neurocriminology and neurolaw are still very young fields, dominated mostly by theory and correlation. In the two decades since the case of the school teacher’s tumor, the field of neuroscience and the use of neuroscientific evidence in a court of law have evolved rapidly, and yet we continue to grapple with the same questions about ethics, admissibility, and accessibility. Brain imaging has the potential to provide a unique perspective on the neural processes behind crimes, but limiting accessibility to only high-profile court cases will only perpetuate the existing cycle of oppression existing in the United States criminal justice system. What’s more, correlating behavioral characteristics to physical brain matter has sparked controversy and allowed for discriminatory views and racial stereotyping [17]. While the integration of neuroscience into law is exciting, it is also imperative that the system takes every step necessary to ensure that brain imaging, neurological assessments, and expert testimonies for use in the courtroom are accessible and foster equal opportunities for justice across all defendants. If not handled with care, those in power have an opportunity to leverage brain science in the courtroom in hopes of absolving heinous criminal acts and exploiting those without resources, including access to private lawyers and neurological consultations [17]. Similar early ethical issues in neuroscience foreshadowed the fine line between the ethical and unethical domains which the modern-day field of neurocriminology treads.

If neuroscience continues on its current trajectory and continuously gains influence in the courtroom, it should remain as simply an aid for a holistic understanding of a crime and the human that committed it. That being said, it is becoming increasingly clear that the criminal justice system is inextricably linked to mental health, psychology, and neuroscience. We hope that inviting neuroscientific evidence into the courtroom encourages humanity and empathy from judges and juries. In cultivating a symbiotic relationship between science and the law, our evolving understanding of the brain’s role in behavior promises inspiring new avenues of treatment and rehabilitation to reduce recidivism and provide better care for our communities.


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