Courts routinely engage in counterfactual analysis—considering what might have been, had things been different—in a variety of legal contexts (such as determining causation for tort claims and establishing damages). But in the last two Terms, the Supreme Court has issued several opinions restricting the use of counterfactual reasoning in the context of federal habeas corpus review of state criminal convictions (under § 2254(d) of the Antiterrorism and Effective Death Penalty Act, or AEDPA). Specifically, the Court has refused to consider what state courts might have done if presented with a slightly different set of facts or law. This practice leaves a group of petitioners without redress for acknowledged constitutional violations.

This Note presents a novel framework for categorizing the modes of counterfactual reasoning in which courts engage. It then analyzes the Court’s decision in Cullen v. Pinholster and related opinions, examining them for possible explanations for the Court’s departure in habeas cases from its usual practice of accepting the need for counterfactuals. It concludes that the Court has given no clear reason why it should depart from the usual background principle that counterfactual reasoning is a valid method of analysis. Finally, it proposes a more coherent scheme for addressing counterfactuals in habeas proceedings.