The Admissibility of Expert Witness Testimony Based on Adolescent Brain Imaging Technology in the Prosecution of Juveniles: How Fairness and Neuroscience Overcome the Evidentiary Obstacles to Allow for Application of a Modified Common Law Infancy Defense

Adolescent brain imaging technology is an evolving area of science that reveals levels of maturity in the adolescent brain. Its potential effect on criminally culpable behavior is the source of extensive debate. The technology can inform judges and jurors on essential differences between how adults make decisions regarding their conduct as distinct from adolescents. United States Supreme Court precedence provides a relevant framework from which we can extrapolate fairness principles and their operation in developing a meaningful juvenile defense under which the technology can be considered. These principles should guide decisions made by the trial courts under the states’ applicable rules of evidence regarding the admissibility of scientific data like adolescent brain imaging technology. Admitting the technology and expert witness testimony in the context of an Infancy Defense model provides the fact finder with the data necessary to make a more in depth determination of adolescent criminal capacity.
Most Infancy Defense statutes currently implemented by the states create a gap comprised of fourteen to eighteen-year-olds by failing to address this population of adolescents whose deficiencies in judgment and decision-making pose the most credible argument for criminal exoneration. Offering adolescent brain research as part of an Infancy Defense model provides juveniles with an opportunity to combat harsher penalties imposed by the states and facilitates imposition of legal standards that require consideration of the differences between children and adults. If juvenile offenders are to be truly considered less blameworthy than adults, preservation of the Infancy Defense is crucial. This is true even when they should be held accountable for their actions. By allowing the juvenile offenders to offer expert witness testimony based on adolescent brain imaging as part of the meaningful defense, the fact-finder can more fairly assess adolescents’ decision-making capacity. Consequently, we must allow the admissibility of adolescent brain imaging in order to guard against overestimation of an adolescents’ criminal culpability.