Recently posted on SSRN: "G2i Knowledge Brief: A Knowledge Brief of the MacArthur Foundation Research Network on Law and Neuroscience"
DAVID L. FAIGMAN, University of California Hastings College of the Law
RICHARD J. BONNIE, University of Virginia - School of Law
BJ CASEY, Yale University - Department of Psychology
ANDRE DAVIS, US Court of Appeals - Fourth Circuit
MORRIS B. HOFFMAN, Second Judicial District Court Judge, State of Colorado
OWEN D. JONES, Vanderbilt University - Law School & Dept. of Biological Sciences
READ MONTAGUE, Virginia Polytechnic Institute & State University - Virginia Tech Carilion Research Institute
STEPHEN MORSE, University of Pennsylvania Law School
MARCUS E. RAICHLE, Washington University School of Medicine
JENNIFER A. RICHESON, Yale University - Department of Psychology
ELIZABETH S. SCOTT, Columbia University - Law School
LAURENCE STEINBERG, Temple University
KIM A. TAYLOR-THOMPSON, New York University School of Law
ANTHONY D. WAGNER, Stanford University - Psychology
GIDEON YAFFE, Yale Law School
Courts are daily confronted with admissibility issues – such as in cases involving neuroscientific testimony – that sometimes involve both the existence of a general phenomenon (i.e., “G”) and the question of whether a particular case represents a specific instance of that general phenomenon (i.e., “i”).
Unfortunately, courts have yet to carefully consider the implications of “G2i” for their admissibility decisions. In some areas, courts limit an expert’s testimony to the general phenomenon. They insist that whether the case at hand is an instance of that phenomenon is exclusively a jury question, and thus not an appropriate subject of expert opinion. In other cases, in contrast, courts hold that expert evidence must be provided on both the group-data issue (i.e., that the phenomenon exists) and what is called the “diagnostic” issue (i.e., that this case is an instance of that phenomenon).
Consequently, the MacArthur Foundation Research Network on Law and Neuroscience has prepared this knowledge brief to help courts manage the G2i divide. Specifically, we recommend that courts first determine whether proffered expert testimony concerns only the existence of the general phenomenon or instead concerns both that and the diagnosis that a particular case represents an instance of that phenomenon. Only after making that determination should the court make its admissibility decision (guided, for instance, by the Daubert factors for admitting scientific evidence).
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