These 15 death-row inmates had numerous neuropsychiatric symptoms that were not addressed. It was thought that the attorneys and judges did not address the organic conditions because of their subtle nature. Objective evidence through collateral and testing ruled out malingering, as did the fact that these inmates were not searching for evaluations or exaggerating their symptoms. The authors concluded that neuropsychiatric status could be a potentially strong mitigating factor, but such evidence is often neglected.
TBI and the insanity defense
Criminal responsibility is dependent on actus reus, the harmful act, and mens rea, guilty or wrongful intent. The accountability and blameworthiness of the crime fall under mens rea. Do TBI patients have the mens rea for the crime? Can TBI be a basis for a plea of not guilty by reason of insanity (NGRI) or a diminished capacity defense? Can the worsening of TBI-related behaviors by substance abuse be the basis for an insanity defense or diminished capacity?
For an NGRI plea, a mental illness or defect must exist. TBI is an abnormal condition of the mind leading to a mental disease that can substantially affect control of emotions and behaviors. The NGRI plea historically had two prongs: cognitive and volitional impairment.9 The M’Naghten test, the cognitive prong, is based on whether the defendant knew the nature and quality of the criminal act or knew the act was wrong. Under the American Law Institute (ALI)test and American Bar Association standards, the defendant can meet the criteria for insanity by demonstrating a substantial lack of capacity to appreciate, rather than knowing, the criminality or wrongfulness of the act.
There is a substantial amount of evidence for cognitive impairment in TBI patients. The TBI patient may have several co-existing “neurolinguistic deficits associated with the pragmatics of language.”10 For example, a TBI patient with damage in the nondominant hemisphere may misinterpret the prosody of language, leading to an inappropriate response. Other neurolinguistic deficits in TBI patients include decreased intelligibility, a constricted operational vocabulary, perseveration, and limited listening.
TBI can also lead to short-term memory impairment due to injury to the vulnerable hippocampus within the anterior temporal lobe. When the hippocampus is damaged, the transformation of memories from long-term to active is impaired. Consequently, retrieval of learned information is more difficult for the TBI patient.10
Also, higher-order cognitive processes can be damaged after TBI. Executive functioning, through the frontal lobe, involves data collection, prioritizing, formulating a plan, and carrying out the plan. This process is almost always impaired in TBI patients, according to a study by Szekeres et al in 1987.14 Poor abstraction associated with frontal lobe damage can lead to difficulties of TBI patients in understanding or appreciating certain concepts related to the wrongfulness, nature, and quality of their acts.
Finally, interpretation of sensory input is impaired as a result of widespread subcortical damage. Deficient central processing could lead to inability to realistically perceive the external world.10 In theory, the TBI patient could potentially have enough cognitive impairment to have a substantial lack of appreciation of the criminality or wrongfulness of an act.
The insanity defense reforms after John Hinckley’s attempted assassination of former President Ronald Reagan have rendered the volitional prong largely irrelevant. One way to judge volitional control is the “policeman at the elbow,” defined as a lack of control such that the offender would have committed the act with a police officer present. Although studies have not focused on whether TBI can lead to “policeman at the elbow” impulsivity, they have proven that TBI-related deficits can lead to severe impulsivity through neuroanatomy and neurotransmitter systems. Silver et al developed the specific diagnosis of “organic aggression syndrome” to describe TBI patients whose aggression is characterized as being “reactive,” “nonreflective,” “nonpurposeful,” “explosive,” “periodic,” and “ego-dystonic.”10
Diminished capacity and mens rea testimony can be subdivided into four categories under the ALI model Penal Code formulation, including “purpose,” “knowledge,” “recklessness,” and “negligence.”9 If an offender has purpose or knowledge, he or she specifically intended to commit the crime. In contrast, with negligence, the offender should have been aware of the risk but may not have been. If the offender is reckless, he or she consciously disregarded a known risk. In general, TBI-related impulsivity and cognitive impairment can lead to recklessness and negligence.
As previously discussed, substance abuse is frequently comorbid in the TBI patient. Evidence for intoxication often exists at the time of the offense. Although the effects of drugs and alcohol might be more severe in such a patient, and the patient probably knew this, the intoxication remains voluntary. An NGRI plea might be unobtainable with voluntary intoxication, but diminished capacity remains a possibility (albeit a weak one).