How Can Criminal Forensic Neuropsychology Be of Assistance in Legal Proceedings?
Forensic neuropsychologists’ contributions can be critical in assisting the trier of fact in terms of the neuropsychologist’s knowledge of cognitive functions, brain-behavior, relationships, psychometric data, knowledge of cognitive and behavioral expressions of syndromes, psychopathology, and symptom exaggeration. In the field of criminal forensic neuropsychology, the forensic neuropsychologist can help rule in or rule out malingered cognitive deficits using empirically validated, specific instruments that detect malingered cognitive or psychiatric symptoms.
Forensic neuropsychologists can be helpful in commenting on whether the person opined to be incompetent can be restored, taking into account that person’s neurologic, psychiatric, and criminal history. If the defendant is suspected to be incompetent because of the cognitive sequelae of a brain injury or dementia, the forensic neuropsychologist can offer a prognosis and an opinion on the likelihood that the defendant will become competent again in the future, based on recovery trajectories, knowledge of the condition, and the relationship between the disorder, injury, cognitive deficits and the legal standards for competence. The forensic neuropsychologist can outline the timeline to restoration, proposed treatments and associated costs, and probability of restoration.
Severity of injury is an important consideration in these cases. Residual effects of traumatic brain injury (TBI) can potentially affect competence to stand trial in some cases (e.g., some cases where dementia is present due to TBI); however, a mild TBI would be quite unlikely to affect competence to stand trial. It is also important to note that in many if not most cases individuals with dementia due to TBI are still competent to stand trial. In one non-TBI case with which I am familiar where competence to stand trial was felt to be affected by a neurologic condition, the forensic neuropsychologist had diagnosed a degenerative dementia and results of the evaluation showed that the person did not have the ability to assist legal counsel in a manner necessary for sentencing. The person in such a case may have difficulty following lines of reasoning when discussing their defense, difficulty recalling prior discussions, and difficulty speaking on their own in a rational manner and in a manner necessary (when asked to recall facts of the case) due to memory or executive functioning deficits.
Another role of forensic neuropsychologists in “mental status at time of offense” or competency to stand trial cases is to opine on preexisting (pre-crime) contributors to the picture. Cognitive deficits resulting from disorders diagnosed in infancy, childhood, or adolescence, such as mental retardation, learning disorders, and developmental disorders, may have contributed in some cases to criminal behavior. In some cases these issues have not been fully appreciated or worked up prior to the trial. Forensic neuropsychologists can contribute to documentation of relevant conditions and raise the issue for fuller consideration by the jury during sentencing and mitigation.
Testing is frequently critical in cases where the questions of mental status at time of offense or competency to stand trial are raised (criminal forensic neuropsychology). There are formal competency assessment instruments which can be administered by the forensic neuropsychologist to help answer these questions, although the forensic neuropsychologist is also heavily reliant on obtaining a good history using records review and interviews with others knowledgeable of the defendant’s history. Testing of cognitive functioning is especially helpful in cases where cognitive concerns are raised,and can assess for malingered neurocognitive dysfunction. Over the past 10 years, there have been significant advances in detecting feigned versus genuine neurocognitive deficits within the field of neuropsychology, which can be extraordinarily helpful when evaluating claimed amnesia for crimes. Amnesia can be organically based, such as due to a dementia, tumor, severe TBI or stroke, or alcohol or drug induced intoxication (although knowledge of intent and actions remains a very controversial area of study in cases of claimed amnesia due to substance use); psychogenic (due to psychiatric conditions or factors); and malingered.
Most neuropsychologists are not routinely involved in competency to stand trial evaluations, part of the branch of the field known as criminal forensic neuropsychology. It has been my observation to date, and that of others, that crimes carried out by individuals with severe neurological compromise tend to be very minor in many cases. It appears that the majority of individuals who have successfully pursued an insanity defense have a major mental illness, particularly psychosis. Even then, most defendants diagnosed with mental illness are not considered insane and are considered competent to stand trial. There has been limited support for insanity based on organic mental disorder. However, the evaluation can be quite helpful during the sentencing and mitigation phases of the case. I have been expert consultant or witness in several cases where competency to stand trial was raised, and observed that when the defendant claims amnesia, when there is a suspicion of dementia or a recent head injury or other neurological illness that could impair the cognitive abilities underlying competence, neuropsychological assessment was a valuable addition.
To identify an individual who can perform evaluations in the area of criminal forensic neuropsychology, you may consult the directory of board certified neuropsychologists at http://www.theaacn.org. The American Academy of Forensic Psychology (http://www.aafp.abfp.org) is also a great resource.