What does recent neuroscience tell us about criminal responsibility?

Abstract

A defendant is criminally responsible for his action only if he is shown to have engaged in a guilty act-actus reus (eg for larceny, voluntarily taking someone else's property without permission)-while possessing a guilty mind-mens rea (eg knowing that he had taken someone else's property without permission, intending not to return it)-and lacking affirmative defenses (eg the insanity defense or self-defense). We therefore first review neuroscientific studies that bear on the nature of voluntary action, and so could, potentially, tell us something of importance about the actus reus of crimes. Then we look at studies of intention, perception of risk, and other mental states that matter to the mens rea of crimes. And, last, we discuss studies of self-control, which might be relevant to some formulations of the insanity defense. As we show, to date, very little is known about the brain that is of significance for understanding criminal responsibility. But there is no reason to think that neuroscience cannot provide evidence that will challenge our understanding of criminal responsibility.

Keywords: Intention and perception of risk; neuroscience and criminal responsibility; neuroscience and law; self-control; voluntary action.

Figure 1.

Decoding outcome of decisions over time before they were reported to reach awareness. The three gray patches designate regions where the specific outcome of a motor decision could be decoded before it had been made (mean ± s.e.m.; filled circles indicate significant decoding accuracy at p < 0.05). The vertical red line shows the earliest time at which the subjects became aware of their choices. The dashed (right) vertical line in each graph shows the onset of the next trial. (Adapted with permission from Soon et al., 2008.)

Figure 2.

Premotor and parietal responsive sites shown after registration of the individual MR images to the MNI template. Left stimulations have been reported on the right hemisphere. Colored areas define the anatomical boundaries of Brodmann Area (BA) 40, BA 39, and BA 6. (Adapted with permission from Desmurget et al., 2009.)

Figure 3.

(A) an illustration of the task progress. (B) Brain regions encoding the subjects’ specific intentions during either the delay (light gray) or execution (dark gray) periods. (MPFCa, anterior medial prefrontal; MPFCp, posterior medial prefrontal cortex; LLFPC, left lateral frontopolar cortex; LIFS, left inferior frontal sulcus; RMFG, right middle frontal gyrus; LFO, left frontal operculum.) (Adapted with permission from Haynes et al., 2007.)

Figure 4.

(A) The experimental setup in the clinic. The patient and experimenter are watching the game screen (inset on bottom right) on a computer (bottom left) and still pressing down the buttons of the response box. The real-time system already computed a prediction, and thus displays an arrow on the screen behind the patient and plays a tone in the experimenter's ear ipsilateral to the hand it predicts he should raise to beat the patient. (B) Across-subjects average of the prediction accuracy (mean ± s.e.m. shaded) versus time before the go signal. Values above the dashed horizontal line are significant at p = 0.05. (Adapted with permission from Maoz et al., 2012.)

Figure 5.

(A) Depictions of the experimental progress during the health, taste and decision blocks (in grayscale). (B) The vmPFC (top) may control the DLPFC (bottom) through an intermediate brain region like IFG (inferior frontal gyrus, BA 46; middle). (Adapted with permission from Hare et al., 2009.)