Supreme Confusion About Causality at the Supreme Court

Twice in the 2020 term, in Bostock and Comcast, the Supreme Court doubled down on a particular interpretation of how “but-for causation” applies to antidiscrimination statutes. According to the Court’s reasoning, an outcome is discriminatory because of some status—say, sex or race—if the outcome would not have occurred “but-for” the plaintiff’s status. We think this reasoning embeds profound conceptual errors that render the decisions deeply confused. Furthermore, those conceptual errors tend to limit the reach of antidiscrimination law.

In this essay, we first unpack the ambiguity of the Court’s interpretation and application of but-for causal reasoning. We then show that this reasoning arises from a misapplication of tort law principles within antidiscrimination law, and that, as a result, it is both conceptually and normatively indeterminate.