Supplemental Jurisdiction

Supplemental jurisdiction, codified at 28 U.S.C. Section 1367, allows a federal court to hear claims that do not independently satisfy subject-matter jurisdiction requirements when those claims are so related to claims within the court's original jurisdiction that they form part of the same case or controversy under Article III. The doctrine prevents parties from having to split related claims between federal and state courts.

The statutory framework has two key components. Section 1367(a) grants supplemental jurisdiction over all claims that share a common nucleus of operative fact with the jurisdictionally sufficient anchor claim. This language, drawn from United Mine Workers v. Gibbs (1966), means that the federal and supplemental claims must arise from the same transaction or occurrence such that a plaintiff would ordinarily be expected to litigate them in a single proceeding.

Section 1367(b) contains an important limitation for diversity cases. To prevent parties from using supplemental jurisdiction to circumvent the complete diversity requirement, Section 1367(b) excludes certain claims by plaintiffs against persons made parties under Rules 14, 19, 20, or 24, or claims by persons proposed to be joined as plaintiffs under Rule 19 or seeking to intervene under Rule 24, when exercising jurisdiction over those claims would be inconsistent with the diversity statute. The Supreme Court in Exxon Mobil Corp. v. Allapattah Services held that Section 1367(a) overruled the Zahn v. International Paper requirement of complete diversity of amount in controversy for class actions — only one plaintiff must meet the amount in controversy, and supplemental jurisdiction extends to the others.

Section 1367(c) gives district courts discretion to decline supplemental jurisdiction in four situations: when the state claim raises a novel or complex issue of state law, when the state claim substantially predominates, when the court has dismissed all claims over which it has original jurisdiction, or in other exceptional circumstances. Courts routinely decline supplemental jurisdiction when the federal claims are dismissed early in the litigation, remitting the parties to state court for the remaining state-law claims.