T. M. v. University of Md. Medical System Corporation

Majority reasoning

The majority held that the Rooker-Feldman doctrine's core logic — that federal district courts have only "original" jurisdiction (the power to hear new cases) and not "appellate" jurisdiction (the power to review another court's decision) — applies regardless of whether the state court judgment is still being appealed. The Court reasoned that when a party asks a federal district court to declare a state court judgment void or unconstitutional, that party is effectively asking the district court to act as an appeals court over the state court, which only the U.S. Supreme Court is authorized to do. The majority rejected the argument that Rooker-Feldman should be limited to judgments that have reached the state's highest court, finding that prior precedents never imposed that requirement and that the doctrine's reasoning applies equally to lower state court judgments still on appeal. The Court also warned that allowing federal district courts to review state judgments mid-appeal would undermine cooperation between state and federal court systems, encourage parties to rush to federal court while state appeals are pending, and produce arbitrary results depending on the timing of when a federal suit is filed. Finally, the majority declined to address arguments that the Rooker and Feldman cases were wrongly decided in the first place, since that question was not properly before the Court.

Dissent reasoning

The dissent argued that the Court's 2005 decision in Exxon Mobil Corp. v. Saudi Basic Industries Corp. already settled this question by confining Rooker-Feldman to cases where the state court proceedings had fully ended — a feature Exxon specifically identified as present in both original Rooker-Feldman cases. Seven federal appeals courts had read Exxon that way, and the dissent argued they were correct. The dissent also raised deeper doubts about Rooker-Feldman's foundations, arguing that a "collateral attack" on a judgment in a new lawsuit is fundamentally different from an appeal, and that Congress's grant of broad federal question jurisdiction to district courts does not contain a carve-out for cases that challenge state court judgments. The dissent contended that existing legal tools — including preclusion rules, abstention doctrines, and the Full Faith and Credit Act — already handle the situations Rooker-Feldman is meant to address, making the doctrine largely redundant. The dissent further argued that the majority's reliance on "federalism" as a rationale is inconsistent with Exxon, which rejected similar federalism-based reasoning, and is in tension with statutes like 42 U.S.C. §1983, which was specifically designed to allow federal courts to protect people from unconstitutional state court action.