## Facts

- Anastasia Wullschleger bought dog food made by Royal Canin U.S.A., Inc. that was priced higher than ordinary dog food and sold only with a veterinarian’s prescription.
- Wullschleger later learned the product did not contain medication or other features that, in her view, justified the prescription requirement or the premium price.
- Wullschleger sued Royal Canin in Missouri state court, bringing state-law claims (including under Missouri’s merchandising-practice statute and Missouri antitrust law) and also asserting a claim under the federal Food, Drug, and Cosmetic Act (FDCA).
- Royal Canin removed the case to federal district court under 28 U.S.C. § 1441(a), relying on federal-question jurisdiction under 28 U.S.C. § 1331 based on the FDCA claim; the district court could also hear the related state claims, if at all, only through 28 U.S.C. § 1367 supplemental jurisdiction.
- Wanting to litigate in state court, Wullschleger amended her complaint after removal to delete the FDCA claim, leaving only state-law causes of action.
- Wullschleger moved to remand. The district court denied remand and later dismissed the case.
- The Eighth Circuit reversed, holding that once the operative complaint contained no federal claim, the federal court lacked a statutory basis to keep the case; it ordered remand.
- The Supreme Court granted certiorari to resolve disagreement among the circuits on whether federal courts may keep state-law claims after a post-removal amendment removes the only federal claim.

## Issues

1. After a case is removed based on federal-question jurisdiction, does a plaintiff’s amended complaint eliminating the only federal claim defeat federal-question jurisdiction under 28 U.S.C. § 1331?
2. If the operative complaint contains only state-law claims after the amendment, may the federal court nonetheless retain the case under supplemental jurisdiction, or must it remand?

## Decision

- The Supreme Court unanimously affirmed the Eighth Circuit in an opinion by Justice Kagan.
- When a plaintiff amends the complaint after removal to eliminate the federal-law claim that supplied federal-question jurisdiction, and the operative complaint then contains only state-law claims, § 1367 does not authorize the federal court to continue exercising supplemental jurisdiction over those claims.
- Because the amended complaint left no claim within the district court’s original jurisdiction, the district court was required to remand the case to state court rather than proceed to adjudicate (and dismiss) the state-law claims.

## Legal Principles

- In assessing subject-matter jurisdiction in this setting, the operative complaint matters; if an amendment removes all federal claims, the court must evaluate jurisdiction based on the amended pleading.
- Supplemental jurisdiction under 28 U.S.C. § 1367(a) extends only to claims that are part of the same Article III “case or controversy” as claims within the district court’s original jurisdiction; the statute’s grant depends on the existence, in the action as currently pleaded, of at least one claim within original jurisdiction.
- When a removed case becomes purely state law because the plaintiff has amended away the only federal claim, there is no remaining basis for § 1331 jurisdiction, and § 1367(a) no longer supplies authority to keep the state claims in federal court.
- This situation is distinct from cases in which a federal court dismisses federal claims on the merits and then considers whether to keep state-law claims under § 1367(c); here, the post-removal amendment leaves the court without the statutory predicate for supplemental jurisdiction in the first place.
- Concerns about plaintiff gamesmanship do not permit a federal court to retain a removed, state-law-only action when Congress has not granted jurisdiction for it.

## Conclusion

Royal Canin held that when a case is removed on the basis of a federal question and the plaintiff then amends the complaint to remove the only federal claim, the federal court loses the statutory basis to exercise supplemental jurisdiction over the remaining state-law claims and must remand the case to state court.


Royal Canin U.S.A., Inc. v. Wullschleger, 145 S. Ct. 41 (2025)