This Essay asserts that in McCleskey v. Kemp, the Supreme Court created a problematic standard for the evidence of race bias necessary to uphold an equal protection claim under the Fourteenth Amendment of the U.S. Constitution. First, the Court’s opinion reinforced the cramped understanding that constitutional claims require evidence of not only disparate impact but also discriminatory purpose, producing significant negative consequences for the operation of the U.S. criminal justice system. Second, the Court rejected the Baldus study’s findings of statistically significant correlations between the races of the perpetrators and victims and the imposition of the death penalty within Georgia criminal courts as insufficient proof of discriminatory intent, overlooking unconscious and structural racism. Third, Justice Lewis Powell’s approach to causation in McCleskey would have rendered almost any social science study incapable of proving the existence of race bias to his satisfaction, creating an unduly high bar for proving intent. Furthermore, this Essay contrasts the Court’s use of the Baldus data in McCleskey with its use of social science data in other cases. For example, in oral arguments for a recent gerrymandering case, Gill v. Whitford, Chief Justice John Roberts summarily rejected the utility of applying empirical findings. In Brown v. Board of Education, by contrast, the Court positively endorsed studies on the harms of racial segregation that were less robust than the Baldus data. In response to uneven uses of empirical data in these cases, this Essay suggests approaches courts might develop to distinguish between stronger and weaker empirical evidence, including an update of how appellate courts review research introduced under the Daubert v. Merrell Dow Pharmaceuticals, Inc. standard. In the wake of decisions such as McCleskey, and the troubled history of considerations of race within social science research, this Essay also articulates the unique challenges that must be confronted when courts consider data on racial impact.