“The Magic of Numbers is Strong”: Hobson v Hansen and Contested Social Science in Judicial Decision Making

Abstract Hobson v. Hansen (1967) is best known as the first federal court case to rule against discriminatory use of standardized tests in the context of educational tracking. It was also significant as one of the first desegregation cases after Brown v Board of Education (1954) to use psychological evidence in its ruling. This essay briefly examines the debates over ability testing before Hobson, the contexts of post-desegregation D.C. educational politics that shaped the case, the social scientific evidence presented in the case, and its application to the court’s ruling. It argues that while scholars have correctly acknowledged the court’s mistaken assumptions about testing, the evidence presented of testing bias nevertheless cogently illustrated a broader constellation of discriminatory District practices. A review of the testimony suggests that while the psychological evidence was central to the court’s ruling, the opinion rested less on the resolution of social scientific debates over testing bias than it did on the need to determine the justification of ability testing in the context of District tracking practices. Although sweeping in scope, the decision did little to resolve long running disputes over ability testing. Instead, it only helped inaugurate a more heated and contentious legal environment for educational testing in the coming decades.