The remarkable advances in brain imaging technology in recent years have allowed us to discover much about the neurobiology of antisocial personality traits and behavior. For example, on average, violent felons have reduced functioning in the frontal lobe and psychopathic prisoners have under-responsive amygdalas. But what does this mean for responsibility? Are violent criminals less culpable if their brains are abnormal? Are psychopaths less accountable if their brain is less able to process empathy?

Presumably small differences in brain function should not be a “get out of jail free” card. Most psychologists agree that people need to be held accountable to the extent that they have choice and control over their actions. On the other hand, brain abnormalities can be used as evidence of mitigating factors. For example, a nonviolent first offender might receive a lesser sentence if there is evidence of recent head trauma. Most importantly, however, neurobiological research can help with treatment and prevention of antisocial behavior, to protect society from future crimes.