In the absence of rigorous science, psychologists disagree about using the neurobiology of stress to defend police officers who kill.

Defense attorneys and prosecutors alike have long relied on expert testimony by psychologists to help divine the complex soup of chemical hormones and electrical impulses that drive human behavior. But the use of psychology in the defense of police officer shootings is less common—in part because so few officers ever end up on trial. But when they are, testimony on the unique and stressful psychological tableau of police work has become a staple for the defense.

Some psychologists argue that while the biology of stress is well established, its connection to deadly force is far less clear. While officers can experience cognitive and perceptual impairments, like tunnel vision and dissociation, during deadly encounters, researchers ultimately know very little about what role they play in the decision to use deadly force. In the absence of rigorous science, psychologists are dubious of using the neurobiology of stress in defense of police officers who kill.

Lisa Fournier.

Of course, everyone deserves a vigorous defense. “But the defense must also be rational,” said Lisa Fournier, professor of psychology at WSU and an editor at the American Journal of Psychology. That means expert witnesses should have no conflicts of interest, refrain from cherry-picking, and only cite peer-reviewed articles.

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Scientific American