Why Supplemental Jurisdiction Exists

Related Claims in Federal Court

Why Supplemental Jurisdiction Exists

Federal courts decide subject-matter jurisdiction claim by claim, not case by case. Every claim in a district court needs its own statutory “ticket of admission,” whether the ticket reads § 1331, § 1332, or some other statute that vests jurisdiction in the court, and a complaint with several counts must show a ticket for each count.¹ Supplemental jurisdiction, found in 28 U.S.C. § 1367(a), is a special ticket: it admits a claim that has none of its own, but only as a companion to a related claim that does.²

The claim-by-claim rule runs into the way modern lawsuits are built. The Federal Rules of Civil Procedure allow, and often require, the joinder of multiple claims and multiple parties in one suit.³ A federal court that properly hears one claim acquires no automatic power over a second claim or an added party, because each must qualify on its own. The Rules invite a single comprehensive lawsuit, the jurisdictional statutes admit claims one at a time, and the two pull apart whenever a joined claim lacks a basis of its own.

An employment dispute shows the collision. An employee sues her employer under Title VII and the Pregnancy Discrimination Act, and her claims fit comfortably under § 1331. She also alleges that the firing breached her employment contract. She and the employer are citizens of the same state, so diversity under § 1332 is unavailable, and the contract claim holds no ticket.⁴ The same gap opens if the employee sues only under Title VII and the employer answers with a breach-of-contract counterclaim, because a state-law counterclaim would lack jurisdiction under either § 1331 or § 1332.⁵ In either version, the court has power over the federal claims and, without more, no power over a contract claim that grows out of the same transaction.

Three responses to that gap are possible. The court could hear the federal claims and leave the contract claim to a state court, but that solution is badly inefficient: when the claims arise from the same transaction or occurrence, one court could hear the entire matter and preserve resources. The court could instead send the whole suit to state court, which holds general jurisdiction and can hear both sets of claims, but that solution dramatically limits access to a federal forum. The third response, and the one the law has adopted by statute, takes an expansive approach to federal jurisdiction. Where § 1331, § 1332, or another basis of original jurisdiction covers some but not all of the claims in a suit, the federal court may exercise supplemental jurisdiction and collect the related claims together.⁶

That solution does not work equally well in every setting. Where a federal question organizes the litigation, courts craft a welcoming jurisdictional principle that lets the plaintiff use the federal forum for the federal claim and try related state claims alongside it. Where the plaintiff instead chooses the federal forum for a state-law claim based on diversity, courts offer no expansive rules, and a plaintiff who wants unitary litigation may file all the related claims against all the related parties in state court.⁷

Two questions arise whenever a federal court is asked to extend its jurisdiction in this way. The first is constitutional: may the court hear the added claim consistently with Article III? The second is statutory: has Congress authorized it to do so? The Supreme Court answered the first question in United Mine Workers of America v. Gibbs by treating the case, rather than the claim, as the relevant unit for jurisdictional purposes. A federal claim and a state claim that arise from a common nucleus of operative facts together form one constitutional case.⁸ Congress answered the second question in § 1367(a), which gives the district courts supplemental jurisdiction over claims so related to claims within their original jurisdiction that they form part of the same case or controversy under Article III, and which reaches claims involving the joinder or intervention of additional parties.⁹ Later sections take each question in turn.

Four terms recur throughout the doctrine:

• An anchor claim is a claim with its own basis of original jurisdiction, such as a federal-question claim under § 1331 or a diversity claim that satisfies § 1332.
• A supplemental claim is a related claim, including one that brings in an added party, that has no independent basis and enters the case only because of the anchor claim.¹⁰
• Pendent jurisdiction is the older name for supplemental jurisdiction when the anchor claim is not based solely on diversity, as when it arises under § 1331 or § 1333.
• Ancillary jurisdiction is the older name for supplemental jurisdiction when the anchor claim is based solely on diversity.¹¹

The courts built pendent and ancillary jurisdiction themselves, without statutory authority, and in 1990 Congress codified both as supplemental jurisdiction in § 1367(a).¹² The old labels still matter. Courts continue to use them, and § 1367 continues the earlier preference for pendent jurisdiction over ancillary jurisdiction.¹³

Whatever the label, supplemental jurisdiction never stands alone. Section 1367(a) operates only “in any civil action of which the district courts have original jurisdiction,” so the court must first find an anchor claim and only then ask whether another claim can ride along with it.¹⁴ Without that requirement, joinder could do the work of the jurisdictional statutes: two claims that each belong in state court would become a federal case merely by being filed together.

The New York plaintiffs’ claims may be as closely related as the employee’s federal and contract claims, so relatedness does not decide the result. The employee’s Title VII claim carries its own ticket under § 1331, and the contract claim can accompany it. The New York plaintiffs hold only state-law claims that each fall short of the jurisdictional amount, so nothing in their case can carry the other claims in. Students often treat factual relatedness as sufficient, and it never is: a close connection admits a claim only when some other claim in the action independently falls within original jurisdiction.