Previously posted on SSRN.


One major conundrum in the field of law and neuroscience is that the mental states that are most relevant to legal determinations are often mental states that occurred in the past, and can longer be assessed. Could the defendant, at the time he committed the crime, have had the cognitive capacity to satisfy the required mens rea for the crime charged? Was an individual's tortious conduct intentional or inadvertent? Even if the field of neuroscience eventually gains the ability to provide data relevant to understanding of immediate mental states, those data will be unavailable to legal actors by the time someone is actually interested in gathering them. The issue of mental competency in criminal cases is an exception to this general problem. Unlike most other relevant mental states in the law, competency deals with a criminal defendant's current mental state, during the litigation itself. Surprisingly, however, relatively little scholarship has been written addressing the potential for neuroscience to aid in competency evaluations. We do not have clear data as to how often neuroscience is used in competency evaluations by experts or in hearings conducted by courts. There is virtually no literature discussing how neuroscience data, at our current level of understanding, might be able to aid in determining competency. This article aims to begin to fill that gap, by exploring several ways in which neuroscience could aid in competency determinations.