Supplemental Jurisdiction

28 U.S.C. §1367 - Supplemental Jurisdiction

(a) “[I]n any civil action of which the district courts have original jurisdiction, the district courts shall have supplemental jurisdiction over all other claims that are so related to claims in the action within such original jurisdiction that they form part of the same case or controversy under Article III of the United States Constitution. Such supplemental jurisdiction shall include claims that involve the joinder or intervention of additional parties.”

Supplemental Jurisdiction Test:

If a federal claim is substantive, and state and federal claims derive from a common nucleus of operative fact, then the state claims can be heard alongside the federal claims in federal court. 

  • United Mine Workers v. Gibbs, 383 U.S. 715 (1966)

Amended Complaint Rule:

When an amendment removes the federal-law claims that enabled federal jurisdiction, the federal court loses its supplemental jurisdiction over the related state-law claims. 

  • Royal Canin U.S.A., Inc. v. Wullschleger, 604 U.S. __ (2025)