Brain lesions and their implications in criminal responsibility

Abstract

For over 200 years, Western courts have considered pleas of "not guilty by reason of insanity" (NGRI) for defendants in possession of a mental defect rendering them unable to understand the wrongfulness of their act. Until recently, determining the mental state of a defendant has fallen largely upon the shoulders of court psychologists and experts in psychiatry for qualitative assessments related to NGRI pleas and mitigation at sentencing. However, advances in neuroscience--particularly neurological scanning techniques such as magnetic resonance imaging (MRI), functional magnetic resonance imaging (fMRI), computed tomography scanning (CT), and positron emission tomography scanning (PET)--may provide additional, pertinent biological evidence as to whether an organically based mental defect exists. With increasing frequency, criminal defense attorneys are integrating neuroimaging data into hearings related to determinations of guilt and sentencing mitigation. This is of concern, since not all brain lesions and abnormalities indicate a compromised mental state that is relevant to knowing whether the act was wrong at the time of commission, and juries may be swayed by neuroscientific evidence that is not relevant to the determination of the legal question before them. This review discusses historical and modern cases involving the intersection of brain lesions and criminality, neuroscientific perspectives of how particular types of lesions may contribute to a legally relevant mental defect, and how such evidence might best be integrated into a criminal trial.

The Influence of fMRI Lie Detection Evidence on Juror Decision‐Making

“…The issue of whether or not fMRI evidence has substantial probative value is beyond the scope of this paper, but it well addressed elsewhere (e.g., Feigenson, 2006;Dressing, Sartorius, & Meyer-Lindenberg, 2008;Sinnott-Armstrong et al, 2008). Some legal decisions have concluded that the admission of brain imaging evidence in a criminal trial would be more prejudicial than probative (see Batts, 2009), though others have suggested that if the technology reaches accuracy rates greater than 90%, its admission is inevitable (Rosen, 2007).…”

Neuroimage Evidence and the Insanity Defense

“…This concern is that, when jurors are able to "see" the source of behavior in the image of a malfunctioning brain, they will be substantially more persuaded than they have been by traditional forms of testimony such as behavioral descriptions by lay or expert witnesses or explanations of the behavior offered by psychological and psychiatric experts (Batts, 2009;Brown & Murphy, 2010;Dumit, 1999;Gurley & Marcus, 2008;Rose, 2000;Roskies, 2008).…”

Effects of Brain Lesions on Moral Agency: Ethical Dilemmas in Investigating Moral Behavior

“…In theory, most would agree that behaviors caused by defined brain lesions or abnormalities are not under the control of the individual and thus cannot be called acts or considered as an expression of moral agency. But in practice, brain lesions or other abnormalities often do not prove a lack of understanding the wrongness of a certain act at the time of commission (Batts 2009). Neither does it prove an absent ability to act according to one's insight, which would justify a diminished or missing criminal responsibility in most European countries.…”