Assessing the Context of Evidence: A Bayesian Perspective on the Role of Publicity, Notoriety, and False Memory in the Blasey Ford Testimony to the United States Senate Confirmation Committee for Supreme Court Justice Brett Kavanaugh

Abstract

Interpreting accusatory testimony in judicial and official hearings requires an assessment of its impact on the probability that an accused individual committed an offense or a crime. During a recent Senate Supreme Court confirmation hearing, Dr. Christine Blasey Ford accused Brett Kavanaugh of making unwanted sexual advances and committing a sexual assault. During the live broadcast of those hearings, American viewers were cast into a role, not unlike jurors sitting on a criminal trial. The potential for false memory, notoriety, and publicity to impact testimony is each considered. This paper provides a Bayesian perspective that accounts for the context in which the accusatory evidence is embedded. Bayesian posterior probabilities estimate the likelihood of guilt given the evidence presented in the testimony. Using the presumption of innocence criterion to set the prior probability suggests a small likelihood of guilt. While priors set using other criteria did yield substantially higher posterior probabilities, none reached the “beyond a reasonable doubt” threshold. The broader implications for evaluating evidence within a highly public context are considered.