Human behavior is the product of our genes and our environment. Law courses, such as Mental Health: Deprivations of Life and Liberty and Law and Neuroscience, depend on this adage to illustrate the role of scientific evidence in the criminal justice system.

For decades, the link between genes and the environment has been unknown. But modern scientific discovery has elucidated the underlying mechanism, epigenetics. This mechanism works though modulating the shape and structure of DNA. DNA does not exist simply as a double helix, but actually is wound into impossibly tight groupings (attached to histone proteins) to allow for storage and selective access to the genetic information contained within. By changing the outer structure of nucleotides (the building blocks of DNA), certain genes may become accessible for translation (encoding proteins from nucleotide sequences) and conversely, it may render certain expanses of DNA inaccessible.

This bio-rhetoric, while interesting, seems to stand outside the field of the law at first glance. However there are many ways in which our new understanding of epigenetics may inform our legal decision making.

Post Traumatic Stress Disorder (PTSD) is a complex and treatment resistant disorder that greatly impacts our nation with nearly 6.8% of the US population experiencing the disorder at some point throughout their lives. An even more staggering number, 30%, represents the number of Vietnam veterans who have suffered from the disorder. Next, consider that nearly 1 in 10 inmates has served in the military. The relationship between these factors must be examined given the prevalence of not only PTSD in veterans, but veterans incarcerated.

Epigenetics elucidate how a single event may drastically alter the normal production of neurotransmitters (NTs – the signals of the brain). A traumatic event occurs causing a physiological response so strong, that the body alters the structure of key NTs (e.g. GABA) gene production regions, which in turn causes downstream effects on neural plasticity and circuitry leading to staggering behavioral changes. See this ongoing blog on the research on epigenetic roles in PTSD.

How culpable is a violent act triggered by PTSD? It seems a simple logical jump to ascribe (at least partial) causality to the disorder rather than the man. However, ephemeral flashbacks lacking strong biological evidence are often unpersuasive to juries. The fear of malingering often outweighs reservations of guilt.

Some have suggested that the original traumatic event should be analyzed to determine whether an individual actually suffers from PTSD. This is inadequate and backwards looking. Further, the traditional ‘battle of the experts’, diagnosis versus diagnosis, serves only to mislead and confuse the jury. As with many cases in Mental Health, an inability to empathize and understand the relationship between the disease and the criminal act, may lead to the wrong result. Juries must be informed of the how a single event can reshape and condition an individual’s fear response into an exaggerated and uncontrollable physical response to a perceived threat, rather the simply pointing to a label of PTSD or a list of symptoms. Giving a tangible cause to the criminal behavior is a crucial step in a jury’s necessary understanding.  Assuming the acceptance of PTSD, what role should it play in the criminal justice system: as a mitigating factor, as a refutation of mens rea or as a basis for the insanity defense. Or possibly it could be used even more broadly, as a justification for self-defense or automatism. For a review of PTSD Case Law – See PTSD as a Criminal Defense: A Review of Case Law. Berger, O., McNiel, D., & Binder, R. See also here.

Epigenetics may also play a significant role in damages. Epigenetics has been the basis of arguments attempting to demonstrate second and third-generation damages. See The Ghost in Our Genes: Legal and Ethical Implications of Epigenetics. Rothstein, M., Cai, Y., & Marchant, G.(evidenced by structural changes in children of DES exposed parents). Damages could be limited with evidence of cessation of the disease, demonstrated by how therapy can affect the epigenome (collective term for epigenetic structure of DNA). See Epigenetic biomarkers as predictors and correlates of symptom improvement following psychotherapy in combat veterans with PTSD. Yehuda, Rachel, et al.

Our understanding of epigenetics is but a fraction of the whole, but its role in the criminal justice system in the future is certain. Epigenetics biggest challenge in the past, evidentiary burdens, may finally be hurdled given the recent increase in peer-review and accepted research.

Greg Miraglia

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