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My Brain Made Me Pull the Trigger

The views expressed are those of the author and are not necessarily those of Scientific American.

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Growth in opinions by judges that mention neurology or behavioral science. A decrease occurred in 2012 because of fewer death-penalty cases.

The emerging academic discipline of neuroethics has been driven, in part, by the recognition that introducing brain scans as legal evidence is fraught with peril.  Most neuroscientists think that a brain scan is unable to provide an accurate representation of the state of mind of a defendant or determine whether his frontal lobes predispose to some wanton action.

The consensus view holds that studying spots on the wrinkled cerebral cortex that are bigger or smaller in some criminal offenders may hint at overarching insights into the roots of violence, but lack the requisite specificity to be used as evidence in any individual case.  “I believe that our behavior is a production of activity in our brain circuits,” Steven E. Hyman of the Broad Institute of Harvard and MIT told a session at the American Association for the Advancement of Science’s annual meeting earlier this year. “But I would never tell a parole board to decide whether to release somebody or hold on to somebody, based on their brain scan as an individual, because I can’t tell what are the causal factors in that individual.”

It doesn’t seem to really matter, though, what academic experts believe about the advisability of  brain scans as Exhibit One at trial. The entry of neuroscience in the courtroom has already begun, big time.

The introduction of a brain scan in a legal case was once enough to generate local headlines. No more. Hundreds of legal opinions each year have begun to invoke the science of mind and brain to bolster legal arguments—references not only to brain scans, but a range of studies that show that the amygdala is implicated in this or the anterior cingulate cortex is at fault for that. The legal establishment, in short, has begun a love affair with all things brain.

Nita Farahany, a professor of law at Duke University, laid out the extent of this infatuation at the recent meeting of the Society for Neuroscience. Helped by a team of 20 law students and undergrads, her research sifted through a massive pool of data to find more than 1,500 judicial opinions from 2005 to 2012 in which an appellate judge mentioned neurological or behavioral genetics evidence that had been used as part of a defense in a criminal case.  “The biggest claim people are making is: please decrease my punishment because I was more impulsive than the next person I was more likely to be aggressive than the next person I had less control than the next person,” Farahany said at a press conference.

Most cases where neuroscience evidence was introduced resulted in an unfavorable outcome for the defendant, but not all. A bizarre twist has turned up in some cases in which a defendant overturned a decision that went the wrong way by accusing his counsel of failing to look into whether he had some sort of brain abnormality—ineffective counsel typically being an impossibly difficult claim.  “If you were asleep as a defense counsel the entire time during the trial, if you were dead during the trial or if you failed to investigate a brain abnormality, you can be found responsible for ineffective assistance of counsel,” Farahany said. “That’s a surprising trio.”

There’s more to come. The arrival of brain science in the courtroom is “challenging fundamental concepts of responsibility and punishment,” Farahany said. “Should we hold people responsible for their actions once we understand concepts of impulsivity? Does that square with our fundamental concepts of how and why we hold people responsible?

Brain science has implications as well for the fate of a convicted offender. “This is a country largely focused on retributivism as a basis for punishment,” she continued. “Is that a legitimate justification for punishment or do we need to rethink what we do and instead focus more on rehabilitation. That has its own host of different types of social and ethical concerns and a bad history in this country of judges medicalizing behavior.” Whichever way things go, jurors and judges are going to be hearing a lot more about amygdalae and orbitofrontal cortices.

Image Source: Nita Farahany, Duke University

Gary Stix About the Author: Gary Stix, a senior editor, commissions, writes, and edits features, news articles and Web blogs for SCIENTIFIC AMERICAN. His area of coverage is neuroscience. He also has frequently been the issue or section editor for special issues or reports on topics ranging from nanotechnology to obesity. He has worked for more than 20 years at SCIENTIFIC AMERICAN, following three years as a science journalist at IEEE Spectrum, the flagship publication for the Institute of Electrical and Electronics Engineers. He has an undergraduate degree in journalism from New York University. With his wife, Miriam Lacob, he wrote a general primer on technology called Who Gives a Gigabyte? Follow on Twitter @@gstix1.

The views expressed are those of the author and are not necessarily those of Scientific American.

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  1. 1. Therapistmumbles 4:45 pm 11/25/2013

    While it is true that brain scans are still just one step above phrenology, there are many studies that document the relationship between traumatic brain injury and impulsive, often criminal behavior.

    One prominent neurologist ( I can’t remember who because my brain isn’t working that well) made the point that if someone commits a violent crime and he is found to have a brain tumor, he may be considered not guilty for medical reasons. However, if someone commits a crime, and that person was often abused as a child and has long-term brain injuries as a result, that is rarely, if ever, taken into consideration.

    It may not be a case of “my brain made me do it” as much as a case of “my brain didn’t stop me.”

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  2. 2. R. Douglas Fields 11:44 am 11/28/2013

    Maybe jurors should be given a brain scan. What do you think?

    The arrival of brain science in the courtroom is “challenging fundamental concepts of responsibility and punishment,” Farahany said. “Should we hold people responsible for their actions once we understand concepts of impulsivity? Does that square with our fundamental concepts of how and why we hold people responsible?

    Link to this
  3. 3. silverfeet 5:22 pm 12/2/2013

    All convicted criminals convicted on real evidence like dna
    or something similar like fingerprints or good confessions
    should go to physic jail hospitals and have their brains
    scanned,checked, and rewired if necessary, which would be most of the time.Then in one year,if the rewiring or fix
    was successful they should be checked again to make sure all is holding well. If so they may need to be re schooled
    for a good job and let out.No reason to keep them then. they will be a productive person of society and society
    will save a ton of money supporting a non correctable
    evil doer. Silverfeet

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  4. 4. jayjacobus 10:01 pm 12/25/2013

    People can hear voices, have hallucinations, suffer from obsessions and compulsions. If a perpetrator claims mental issues for the crime and the crime does not give him or her a personal gain from the crime, the courts should weigh the perpetrator’s mental incapacity.

    The court might reduce the charges or the penalty. Perhaps psychological or even medical treatment might be the sentence. Will a brain scan prove a perpetrators innocence? I suspect that the test may provide support but I doubt that it can provide proof. While the court might consider medical and psychological evidence, the court cannot excuse the perpetrator.

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  5. 5. short_sircuit 1:27 pm 01/9/2014

    As someone with bipolar disorder, I realize I cannot normally use the disease as an excuse for committing a crime. Slipping into a psychotic episode however, might make me do something totally out of character, something criminal that I am not even aware of doing. Is it “me” who committed the crime or some warped version of me? not an easy call.

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