Does a federal district court retain supplemental jurisdiction over state-law claims if a plaintiff amends her complaint to delete the federal-law claims that originally enabled the case's removal from state court? This question asks whether a post-removal amendment can divest a federal court of subject-matter jurisdiction. The Court must determine if the rule for cases originally filed in federal court applies equally to removed cases.

• Section 1367(a) provides broad supplemental jurisdiction over "all other claims" within a case or controversy unless Congress "expressly provided otherwise."
• Congress has not expressly stated that an amendment deleting federal claims eliminates supplemental jurisdiction.
• Precedent in *Carnegie-Mellon Univ. v. Cohill* and a footnote in *Rockwell Int'l Corp. v. United States* suggests that a federal court may retain jurisdiction even after the original basis for federal jurisdiction is eliminated via amendment.

• An amended complaint supersedes the original pleading and becomes the operative document for determining subject-matter jurisdiction.
• Once the federal-law claims are deleted, there is no longer a "federal question" to provide original jurisdiction under 28 U. S. C. § 1331.
• Without an underlying claim within the court's original jurisdiction, supplemental jurisdiction under 28 U. S. C. § 1367 vanishes because there is nothing left to supplement.

• The Court held that when a plaintiff amends her complaint to delete the federal-law claims that enabled removal, the federal court loses supplemental jurisdiction over any remaining state-law claims and must remand the case to state court.
• Under 28 U. S. C. § 1367(a), supplemental jurisdiction is only available for claims "so related to claims in the action within such original jurisdiction that they form part of the same case or controversy."
• Relying on *Rockwell Int'l Corp. v. United States*, the Court reasoned that courts must look to the amended complaint, not the original, to determine jurisdiction; thus, withdrawing federal allegations "will defeat jurisdiction" unless replaced by other jurisdictional claims.
• The Court noted that 28 U. S. C. § 1367(a) contains no text distinguishing between cases originally filed in federal court and those removed from state court, meaning the *Rockwell* rule applies to both.
• The Court found that 28 U. S. C. § 1367(c)—which lists reasons a court may decline supplemental jurisdiction—does not mention amendments deleting federal claims, implying such claims are not covered by the grant of jurisdiction in subsection (a) at all.
• This result is consistent with other statutes where amendments "wipe the jurisdictional slate clean," including 28 U. S. C. § 1653, § 1446(b)(3), and § 1332(d)(7).
• The Court observed that in removed diversity cases, adding a non-diverse party destroys jurisdiction under 28 U. S. C. § 1447(e), further demonstrating that jurisdiction follows the operative pleading.
• The Court dismissed the reliance on *Carnegie-Mellon Univ. v. Cohill* and a footnote in *Rockwell*, characterizing them as "dictum" or "drive-by jurisdictional rulings" that lack precedential effect under the standards set in *Wilkins v. United States*, *Arbaugh v. Y & H Corp.*, and *Henderson v. Shinseki*.