Respondent (Bayer) moved in Federal District Court for an injunction ordering a West Virginia state court not to consider a motion for class certification filed by petitioners (Smith), who were plaintiffs in the state-court action. Bayer thought such an injunction warranted because, in a separate case, Bayer had persuaded the same Federal District Court to deny a similar class-certification motion that had been filed against Bayer by a different plaintiff, George McCollins. The District Court had denied McCollins’ certification motion under Fed. Rule Civ. Proc. 23.

The court granted Bayer’s requested injunction against the state court proceedings, holding that its denial of certification in McCollins’ case precluded litigation of the certification issue in Smith’s case. The Court of Appeals for the Eighth Circuit affirmed. It first noted that the Anti-Injunction Act (Act) generally prohibits federal courts from enjoining state court proceedings. But it found that the Act’s relitigation exception authorized this injunction because ordinary rules of issue preclusion barred Smith from seeking certification of his proposed class. In so doing, the court concluded that Smith was invoking a State Rule, W. Va. Rule Civ. Proc. 23, that was sufficiently similar to the Federal Rule McCollins had invoked, such that the certification issues presented in the two cases were the same. The court further held that Smith, as an unnamed member of McCollins’ putative class action, could be bound by the judgment in McCollins’ case.