Supreme Confusion about Causality at the Supreme Court

Twice in the 2020 term, in Bostock and Comcast, the Supreme Court doubled down on the reasoning of “but-for causation” to interpret antidiscrimination statutes. According to this reasoning, an outcome is discriminatory because of some status—say, sex or race—just in case 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 this 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.