Cross-Examining the Brain: A Legal Analysis of Neural Imaging for Credibility Impeachment

Abstract

The last decade has seen remarkable process in understanding ongoing psychological processes at the neurobiological level, progress that has been driven technologically by the spread of functional neuroimaging devices, especially magnetic resonance imaging, that have become the research tools of a theoretically sophisticated cognitive neuroscience. As this research turns to specification of the mental processes involved in interpersonal deception, the potential evidentiary use of material produced by devices for detecting deception, long stymied by the conceptual and legal limitations of the polygraph, must be re-examined. Although studies in this area are preliminary, and I conclude they have not yet satisfied the foundational requirements for the admissibility of scientific evidence, the potential for use - particularly as a devastating impeachment threat to encourage factual veracity - is a real one that the legal profession should seek to foster through structuring the correct incentives and rules for admissibility. In particular, neuroscience has articulated basic memory processes to a sufficient degree that contemporaneously neuroimaged witnesses would be unable to feign ignorance of a familiar item (or to claim knowledge of something unfamiliar). The brain implementation of actual lies and deceit more generally, is of greater complexity and variability. Nevertheless, the research project to elucidate them is conceptually sound, and the law cannot afford to stand apart from what may ultimately constitute profound progress in a fundamental problem of adjudication.