Without thinking: impulsive aggression and criminal responsibility.

In the U.S. the decision to impose criminal responsibility rests on an assumption about the defendant's decision to engage in proscribed conduct. We punish only those who we believe had the capacity to make a choice. In an increasingly violent world, the criminal law and the assumptions upon which it rests are relentlessly tested. A new generation of neuro-imaging technologies offers to provide insights into structural and functional abnormalities in the brain that may limit the autonomy of many dangerous offenders and unravel the fabric of the criminal justice system. How will the results of these technologies be received by the courts--are they relevant to existing formulations of the prima facie case, the insanity defense, or mitigation of sentence; will changes in the science or the law be required to accommodate this knowledge? The new generation of technologies may appropriately play a role in assessing culpable mental states only if they are also reliable. This short article takes on these and a host of other related questions at the intersection between science, law, and science fiction.