Neuroscience and the insanity defense: Trying to put a round peg in a square hole

Abstract

The insanity defense remains one of the most difficult evaluations for a forensic examiner because it requires a retrospective reconstruction of an individual's mental state and extracting that mental state to specific psycholegal criteria (e.g., capacity to understand wrongfulness) at the time of an alleged crime. Some scholars have suggested that neuroimaging can improve the objectivity of insanity evaluations by highlighting brain deficits in the defendant that led to a compromised ability to understand wrongfulness or an inability to comport their behavior to the requirements of the law. This brief review highlights six principal limitations that, to date, have not been appropriately addressed by proponents of using neuroimaging in insanity evaluations. Researchers are encouraged to address these specific limitations to improve its application to insanity defense evaluations. We posit that until this work is completed, neuroimaging provides limited value to insanity evaluations.