New Evidence About Circumstantial Evidence

Judicial fact-finders are commonly instructed to determine the reliability and weight of any evidence, be it direct or circumstantial, without prejudice to the latter. Nonetheless, studies have shown that people are reluctant to impose liability based on circumstantial evidence alone, even when this evidence is more reliable than direct evidence. Proposed explanations for this reluctance have focused on factors such as the statistical nature of some circumstantial evidence and the tendency of fact-finders to assign low subjective probabilities to circumstantial evidence. However, a recent experimental study has demonstrated that even when such factors are controlled for, the disinclination to impose liability based on non-direct evidence — dubbed the anti-inference bias — remains. The present Article describes seven new experiments that explore the scope and resilience of the anti-inference bias. Intriguingly, it shows that this bias is significantly reduced when legal decision-makers confer benefits, rather than impose liability. In so doing, the Article points to a new legal implication of the psychological phenomenon of loss aversion. In contrast, the Article finds no support for the hypothesis that the reluctance to impose legal liability on the basis of circumstantial evidence correlates with the severity of the legal sanctions. It thus casts doubt on the common belief that sanction severity affects the inclination to impose legal liability. Finally, the Article demonstrates the robustness of the anti-inference bias and its resilience to simple debiasing techniques. These and other findings reported in the Article show that the anti-inference bias reflects primarily normative intuitions, rather than merely epistemological ones, and that it reflects conscious intuitions, rather than wholly unconscious ones. The Article discusses the policy implications of the new findings for procedural and substantive legal norms.