The Supreme Court’s decision affirms that ruling. “Wullschleger had reconfigured her suit to make it only about state law,” Justice Elena Kagan wrote for the court. “And so the suit became one for a state court.”
During October oral arguments, Katherine Wellington, a partner at Hogan Lovells representing the pet food companies, argued that the Eighth Circuit’s decision conflicted with the text and structure of Section 1367, which governs supplemental jurisdiction, as well as long-standing precedents.
“It conflicts with the text and structure of Section 1367 and with more than a century of precedent,” Wellington told the court. “Chief Justice [John] Marshall held in Mollan v. Torrance in 1824 that in a diversity case, a federal court’s jurisdiction, once vested, cannot be divested by subsequent events.”
Justice Ketanji Brown Jackson questioned whether federal jurisdiction would remain if a plaintiff dropped federal claims intentionally, asking, “If a plaintiff said, ‘Oops, I didn’t mean to bring the federal claims; I’m dropping them,’ is there still a basis for federal jurisdiction?” Wellington responded that there was not.
