Cornell Law Review Volume 95 Issue 6

Can Bad Science Be Good Evidence? Neuroscience, Lie-Detection, and Beyond

How should the legal system confront the advances in the brain sciences that may possibly allow more accurate determinations of veracity—lie detecting—than those that now pervade the litigation process?  In this Essay, I question the view, widespread among the scientists most familiar with these advances, that the neuroscience of lie detection is not, or at least not yet, nearly reliable enough to be used in civil or criminal litigation or for related forensic purposes.  But in challenging the neuroscientists and their allies, I make no claims about the science of lie detection that go beyond the current state of scientific knowledge or, more importantly, my own ability to speak about the relevant scientific developments.  Rather, I argue that because law’s goals and norms differ from those of science, there is no more reason to impose the standards of science on law than to impose the standards of law on science.  Law must use science, and should always prefer good science to bad.  In some contexts, however, good science may still not be good enough for law, while in other contexts—hence the title of this Essay—bad science, as measured by the standards of scientists, may still have valuable legal uses.  To be clear, my goal in this Essay is decidedly not to argue that neuroscience-based lie detection should, now or even in the foreseeable future, necessarily be admissible in court or used for other forensic purposes.  Rather my goal is to argue that the question of whether the law should use neuroscience-based lie detection cannot be answered by scientific standards of reliability and validity alone.  Science can—and should— inform the legal system about facts, including facts about degrees of reliability and the extent of experimental validity, but the ultimate normative and institutional question of whether and when, if at all, a given degree of validity or reliability is sufficient for some legal or forensic purpose is a legal and not a scientific question.


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