Danger at the Edge of Chaos: Predicting Violent Behavior in a Post-Daubert World
85 Pages Posted: 4 Oct 2002
Date Written: August 2002
This interdisciplinary article explores the boundaries of predicting violence in the context of capital sentencing decisions. Currently, experts are permitted to proffer opinions in death sentencing proceedings that have little grounding in science, without any examination of the scientific validity of their assertions. They are permitted to do so because, despite being widely castigated as wholly unscientific by the scientific community, predictions of future dangerousness were found to be constitutionally admissible in Barefoot v. Estelle. Standards for evaluating expert testimony have changed considerably since Barefoot, however. The Supreme Court, through its Daubert line of cases, has caused a paradigm shift in the evaluation of scientific evidence in both state and federal courts. The kind of unscientific predictions proffered in Barefoot continue nonetheless to be routinely admitted in sentencing proceedings without any judicial gatekeeping efforts. The tension between the scientific scrutiny required for admissibility even in civil cases (where money damages are at stake) and the unscientific predictions freely admissible in capital sentencing determinations (where the issue is death) is, at best, troubling.
This article explores the validity of dangerousness predictions in light of the latest scientific research about brain structure and function. It also discusses the development of actuarial instruments to assess risk, and compares three predominant actuarial instruments. Based on criteria scientists themselves use to assess validity, as well as the Supreme Court's requirements in Daubert, Joiner, and Kumho Tire, this article outlines a framework for sound analysis of scientific evidence regarding predictions of future violence. Drawing on insights from brain science as well as complexity theory and empirical studies of jury decisionmaking, this article concludes that although actuarial instruments should be used with caution, they offer improvements over the unaided judgment of juries and over the kind of unscientific assertions about future dangerousness currently typical in capital sentencing proceedings. This is an important and timely issue, because the consequences of misleading the jury in a death sentencing determination are severe, not only for the defendant, but for a society that values justice and aspires to rationality.
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