Fourth Circuit Upholds Order Enjoining State Court Action

Today, in an interesting case that presented some thorny procedural issues, the Fourth Circuit upheld a district court order enjoining a North Carolina court from proceeding with a class action, invoking the so-called relitigation exception to the Anti-Injunction Act.

The Fourth Circuit left open a weird issue, which goes something like this: When a district court remands a claim to state court upon declining to exercise supplemental jurisdiction over it, thereby enabling the state court to retain jurisdiction over that claim, but the Fourth Circuit later vacates that district court order on the ground that the subject claim shouldn't have been remanded to state court but instead should've been dismissed, does the vacatur of the district court's order retroactively deprive the state court of jurisdiction? I bet that scenario doesn't arise very often.