Sunday, August 30, 2009
Frederick Schauer (University of Virginia School of Law) has posted Can Bad Science Be Good Evidence: Lie Detection, Neuroscience, and the Mistaken Conflation of Legal and Scientific Norms on SSRN. Here is the abstract:
As the capabilities of cognitive neuroscience, in particular functional magnetic resonance imaging (fMRI) 'brain scans,' have become more advanced, some have claimed that fMRI-based lie-detection can and should be used at trials and for other forensic purposes to determine whether witnesses and others are telling the truth. Although some neuroscientists have been at the forefront of promoting such claim, most neuroscientists aggressively resist them, and have argued that the existing research on neuroscience-based lie-detection is deeply flawed in numerous ways. And so these neuroscientists have resisted any attempt to use such methods in litigation, arguing, in effect, that they are the product, so far, of poor science. But although it is probably true that the existing studies have serious problems of validity when measured by the standards of science, and true as well that the reliability of such methods is significantly lower than their advocates claim, it is nevertheless an error to assume that the distinction between good and bad science, whether as a matter of validity or a matter of reliability, should be dispositive for law. Law is not only about putting criminals in jail, and once we understand that numerous uses of evidence in various contexts in the legal system require a degree of probative value far short of proof beyond a reasonable doubt, we can understand the larger point that legal and scientific norms and standards are different. Some examples of good science may still not be good enough for some legal purposes, and, conversely, some examples of bad science my, in some contexts, still be good enough for some legal purposes.