It has been suggested that the state of mind of the perpetrator of a crime plays a strong part in people's judgement of what constitutes an appropriate punishment. This functional MRI study showed that when people are shown an intentionally harmful act, activity in their amygdala and its connectivity with lateral prefrontal regions was increased. Observers also voted for a stronger punishment for the perpetrator. However, when the same harmful act was perpetrated unintentionally, activity in the observer's amygdala was suppressed by a circuit involving temporoparietal–medial prefrontal regions; views on appropriate punishment severity were also reduced. These findings provide insight into the neural mechanisms underlying emotion-driven punishment.