A rare and well-known neuroimaging case in the court of law is that of a 40-year-old man who inexplicably became a sexual impulsive with pedophilia . He had no history of prior sexual misconduct, but he abruptly began frequenting prostitutes and attempted to molest his 12-year-old stepdaughter . The patient attempted to conceal his activities because he felt they were unacceptable; however, he continued to act on his impulses stating that “the pleasure principle” overrode his urge restraint . After being reported to the authorities, he was found guilty of child molestation and was sentenced to either attend a 12-step sexual addiction program or face jail time .
Despite a strong desire not to go to prison, the patient was unable to inhibit his sexual impulses. It was soon discovered that he had a large tumor pressing on his orbitofrontal cortex . Upon resection of the tumor, the patient’s sexual impulsiveness diminished. When the impulsiveness later returned, a brain scan was able to show reappearance of the tumor. A second resection again diminished the defendant’s sexual impulsiveness . It has been argued that the defendant’s behavior was due to a loss of impulse control as opposed to a loss of moral knowledge; the patient could not refrain from acting despite awareness that his behavior was inappropriate . This case is unique and fascinating in that imaging was able to show a clear causal connection between the tumor and the defendant’s behavior because of the pronounced correlation between the two . Although most cases presenting neuro-scientific evidence in the law are not as clear-cut, with correlations rarely implying causation, neuro-law certainly seems to be a promising new area.
Using functional imaging techniques, various brain regions have been correlated with pro-social behavior. For instance, the anterior cingulate cortex is linked with empathy,the ventromedial prefrontal cortex with ethical decisions, and the orbital prefrontal cortex with regret . It is unsurprising, then, that changes in these brain regions have been associated with criminal behavior. For instance, in people with anti-social personality disorder (APD) there is an 11% reduction in PFC grey matter . Similar reductions were observed in a study of aggressive patients and pathological liars [5, 6]. The amygdala has been a major focus of attempts to understand the poor empathy and fear responses in psychopathic criminals . What is perhaps even more compelling is that there seems to be a higher prevalence of mental illness in incarcerated populations. A systematic review of studies examining mental illness in 23,000 prisoners showed that these prisoners were several times more likely to have some form of psychosis or major depression, and ten times more likely to exhibit APD .
In the Anglo-American criminal justice system, conviction of a crime requires that the state prove two elements: that the accused committed the criminal act (the ‘actus reus’) and that he or she did so with a guilty mind (‘mens rea’) [10, 11]. The relevance of neuroscientific evidence has been implicated in defenses that deny intentions. Other variants of mens rea, such as irresistible impulse and automatism also bear on criminal responsibility . An example of this is the 2007 case of Peter Braunstein, who was charged with kidnapping, sexual abuse, burglary, and arson . On Halloween, he dressed as a firefighter and set off a smoke alarm in the lobby of his coworker’s New York apartment building . He then knocked on her door, claiming that he had come to assess the damage to her apartment. Once she had let him in, he used chloroform to knock her out and then proceeded to sexually assault her for the next 13 hours . A PET scan of the defendant’s brain was performed and introduced into evidence by the defense to show that he was unable to plan the assault of his co-worker . They argued that Braunstein lacked the mens rea to be criminally responsible for the act . A psychiatrist was called to the stand and he indicated that Braunstein had decreased activity in his frontal lobes, which he described as the part of the brain that controls the initiation and cessation of behavior, planning, and moral judgment .
This case is an illustration of one of the problems associated with functional imaging and its presentation. Activity levels in functional imaging are determined by subtracting baseline activity from activity during a particular task. When there is no activation seen on an image, this does not denote that the region was inactive- only that it was not significantly more active than at baseline . A person who is more efficient at performing a particular task may show false results, making it seem as if the relevant region was not activated . Furthermore, levels at which results may be considered significant are not fixed and small differences in activity levels may manifest as dramatic activity on a scan . Additionally, it is crucial to factor in behavior when assessing a crime- a brain scan of the frontal lobes alone is insufficient evidence to postulate that the defendant was lacking in intent as well as the capacity to plan and execute the crime . Braunstein’s intricate actions and behavior do not support these claims and the jury only deliberated for four hours before finding the defendant guilty .
These data introduce complications into moral and legal systems that tend to divide responsibility into dichotomous alternatives- guilty or not guilty- instead of seeing responsibility and free will on a continuum [1, 8]. Although there seems to be a clear correlation between behavior and brain structure, these morphological and volumetric abnormalities may not necessarily cause behavior; this evidence does not insinuate that all criminal or violent behaviors are the result of a dysfunctional brain. However, there is extensive evidence suggesting that certain kinds of dysfunctions are likely to increase the probability of certain behaviors deemed criminal by a society . Neuroscientific evidence, however, is applicable to the insanity defense. A defendant can be excused from liability for a prohibited act if legally insane- that is, if they intentionally commit a proscribed act but are not found blameworthy because a mental condition meeting specified legal criteria prevented them either from knowing the nature of their actions or from understanding the wrongfulness of the act .
Neuroimaging is used as an attempt to demonstrate that the defendant has a neurological or psychiatric condition that predisposed the criminal behavior or caused them to be unaware of, or not responsible for, their actions . Functional imaging evidence has also been used for claims of incompetence to stand trial and pleas for mitigation in sentencing . Neuroscience clearly has much to offer the law. It can be useful in uncovering links between brain activity and behavioral tendencies. On a simpler level, imaging can help determine if the defendant exhibits any neurological damage and whether the resulting brain abnormalities fit with the crime . However, a clear division must be made between the promising aims and aspirations of neuroimaging, as well as the boundaries of what it is capable of achieving.
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- Burns, J.M. and Swerdlow, R.H. 2003. Right orbitofrontal tumor with pedophilia symptom and constructional apraxia sign. Archives of Neurology 60: 437-440.
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- Woermann, F.G., Tebartz van Elst, L., Keop, M.J., Free, S.L., Thompson, P.J., et al. 2000. Reduction of frontal neocortical grey matter associated with affective aggression in patients with temporal lobe epilepsy: An objective voxel by voxel analysis of automatically segmented MRI. Journal of Neurology, Neurosurgery, and Psychiatry 68: 162-169.
- Yang, Y.L., Raine, A., Lencz, T., Bihrle, S., LaCasse, L., et al. 2005. Prefrontal structural abnormalities in liars. The British Journal of Psychiatry 187: 320-325.
- Fazel, S. and Danesh, J. 2002. Serious mental disorder in 23000 prisoners: A systematic review of 62 surveys. Lancet 359: 545-550.
- Glannon, W. 2007. Bioethics and the brain. New York: Oxford University Press.
- Reeves, D., Mills, M.J., Billick, S.B., and Brodie, J.D. 2003. Limitations of brain imaging in forensic psychiatry. The Journal of the American Academy of Psychiatry 31: 89-96.
- Morse, S. 2006. Brain overclaim syndrome and criminal responsibility: A diagnostic note. The Ohio State Journal of Criminal Law 3:397-412.
- Edersheim, J.G., Brendel, R.W., and Price, B.H. 2012. Neuroimaging in Forensic Psychiatry: From the Clinic to the Courtroom 1st ed. Chichester, West Sussex: Wiley-Blackwell.
- Aharoni, E., Funk, C., Sinnott-Armstrong, W., and Gazzaniga, M. 2008. Can neurological evidence help courts assess criminal responsibility? Lessons from law and neuroscience. Annals of the New York Academy of Sciences 1124:145-160.
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