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On Killing: Neuroscience and State-Sponsored Executions

A number of botched executions over the past 16 months have reopened national discourse about the relevance of capital punishment in the 21st century, which has been polarized by passage of a Utah bill reinstating use of the firing squad. As of March 2015, the United States is the lone Western power and one of only 36 nations (18%) worldwide that executes its own citizens. Some common points of contention against state-sponsored execution include, but are certainly not limited to: cases of wrongful execution; distributive injustice, whereby racial minorities are disproportionately executed; diminished mental capacity, which may limit the perpetrator’s moral discernment and decision-making abilities; and insufficient evidence of its deterrent effect on other criminals. On the other hand, death penalty supporters often speak from two conventional perspectives about punishment: (1) a consequentialist perspective – that capital punishment will protect society against that particular convict’s future crimes, and/or (2) a retributivist perspective – namely, an intuitive notion of “an eye for an eye,” that people deserve punishment in proportion to the evilness of their past misdeeds. It’s important to note that retributivists also require proof of criminal intent, known as mens rea. While both sides of the conversation about capital punishment raise defensible points that are worthy of debate, and other perhaps more compassionate approaches to punishment exist, I’ll focus here on the two perspectives most supportive of capital punishment, which neuroscience may have the capacity to inform.

The relevance of both perspectives – consequentialist and retributivist – in this debate is demonstrated in the recent high-profile case of Kelly Gissendaner, the State of Georgia’s only female death-row inmate. Hundreds of faith leaders cite Kelly’s psychological transformation during her time in prison when they insist that the State grant her clemency, which speaks to a consequentialist approach to justice: Kelly is no longer a threat to others, and therefore taking her life, versus lifetime imprisonment, is unwarranted and unjust. By contrast for the pure retributivists, rehabilitation is irrelevant when meting out an individual’s punishment. Such a position was recently articulated by Danny Porter, the District Attorney for Gwinnett Country (GA), who stated that “[Kelly’s] sentence is appropriate for the crime that was committed…and really what she’s done since is almost not something that needs to be considered.” These two perspectives are not necessarily mutually exclusive, but public discourse in this case tends to divide opponents and supporters along consequentialist and retributivist lines, respectively. So how can neuroscience, and possibly neurotechnology, speak to these perspectives?

Consequentialist arguments in the Gissendaner case – that Kelly is rehabilitated and no longer a threat to society – align with our contemporary understanding of neuroplasticity in that the adult brain is capable of profound structural and functional modifications through training and experience. Empirical research using interventions such as meditation [1], yoga [2], and psychotherapy [3], has demonstrated that neural changes correspond with changes in cognition and behavior, particularly in domains that are relevant to morality and criminality, like “empathic accuracy” [4] and “emotional reactivity” [5]. To that end, neurotechnologies like functional magnetic resonance imaging (fMRI) could in theory provide physical evidence of rehabilitation, which might mitigate a defendant’s punishment during parole board proceedings. To my knowledge, this sort of “functional evidence” of rehabilitation has yet to be admitted in court, but carries with it at least one major caveat. In most fMRI research studies, conclusions are based upon group comparisons (e.g. control vs. treatment groups), rather than a single individual’s brain per se. This means that simply scanning one’s brain is insufficient to infer group membership (known as the G2i problem) due to large inter-individual differences in brain activity. In other words, a person’s brain may “look” criminal, but he or she may perform normally on cognitive tests, or vice versa. The take-home message is that behavioral interventions aimed at rehabilitation can and often do have measured, lasting effects on the brain and behavior; however, generating and admitting such functional neuroevidence in court is problematic, at least given our current neurotechnological repertoire.

Retributivist arguments in the Gissendaner case – that Kelly deserves the death penalty for her involvement in taking another’s life – implicitly require that Kelly’s actions were uncoerced, intentional, and autonomous. Kelly can only be held responsible if these conditions are satisfied. Without this assumption, someone could be punished if her crime was compelled by external factors, like being forced at gunpoint to break into someone else’s car. The notion of external factors seems clear at first, but gets complicated in cases like brain tumor-induced pedophilia, or those with gene variants linked to impulsivity and violence [6]. Is one’s brain, and by extension one’s biology, an internal or external factor, or perhaps both? As researchers Joshua Greene and Jonathan Cohen suggest in their 2004 article [7], neuroscience may change criminal justice through shifts in the public’s understanding of human behavior, specifically its notions of  free will and autonomy. As neuroscience continues to discover the myriad ways in which behavior, and inextricably the human brain, is shaped by interactions of biological, psychological, and social forces that include genetics, early-life experiences, cultural environments, and human relationships, individuals will no longer judge others as completely autonomous agents making freely-willed, internal choices. Instead, they will recognize that nobody develops, perceives, thinks, and acts in such a way that is totally free from the many external forces that ultimately converge upon their brains and bodies. In that way, everyone is a little “unfree,” though some more than others. It is my hope that this scientifically-informed perspective will lead to more compassionate, humanistic approaches to criminal justice than the present system allows.

Retributivists beware: the idea of an entirely freely-willed crime may soon die.


1. Tang, YY, Holzel, BK, Posner MI. The neuroscience of mindfulness meditation. Nat. Rev. Neurosci (2015) 16, 213-25.

2. Gard, T, et al. Fluid intelligence and brain functional organization in aging yoga and meditation practitioners. Front Aging Neurosci (2014) 6, 76.

3. Linden, DEJ. How psychotherapy changes the brain – the contribution of functional neuroimaging. Mol Psychiatry (2006) 77, 775-81.

4. Mascaro, JS, et al. Compassion meditation enhances empathic accuracy and related neural activity. Soc Cogn Affect Neurosci (2013) 8, 48-55.

5. Taylor, VA, et al. Impact of mindfulness on the neural responses to emotional pictures in experienced and beginner meditators. Neuroimage (2011) 57, 1524-33.

6. Meyer-Lindenberg, A., et al. Neural mechanisms of genetic risk for impulsivity and violence in humans. PNAS (2006) 103, 6269-74.

7. Green, J. & Cohen, J. For the law, neuroscience changes nothing and everything. Phil. Trans. R. Soc. Lond. B (2004) 359, 1775-85.

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Kohn, J. (2015). On Killing: Neuroscience and State-Sponsored Executions. The Neuroethics Blog. Retrieved on , from


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