Capacity and Mitigation

The U.S. Supreme Court’s recent decision in Roper v. Simmons [1] and the amicus briefs submitted in support of abolishing the death penalty for juveniles suggests that neuroscientific evidence will play an increasingly important role in shaping legal concepts of culpability [2]. As we saw in Chapter 9, neuroscience is already beginning to play an important role in insanity defense proceedings. In addition, when mental conditions do not meet the stringent standards required for exculpation on insanity grounds, they might still be relevant to culpability, either because they influenced the defendant’s mental state at the time of the offense (diminished capacity) or because they reduce the blameworthiness of the defendant for sentencing purposes (mitigation). Neuroimaging in these contexts may shed light on the mental state of the accused at the time of the offense in order to help juries and judges determine the defendant’s quality of thought or level of culpability. In these instances, neuroimaging evidence is relevant to the ‘mens rea’ element of the criminal offense, as explained below.