28 U.S.C. § 1367 is the federal statute on supplemental jurisdiction. It lets a federal court hear a state-law claim that is closely tied to a federal claim already before it, so related disputes stay in one lawsuit instead of being split between two court systems. The statute has four working parts: subsection (a) grants the jurisdiction, subsection (b) restricts it in diversity cases, subsection (c) lets judges decline it, and subsection (d) tolls the statute of limitations if the state-law claim is sent away.
When Supplemental Jurisdiction Applies
Subsection (a) grants jurisdiction over any additional claim “so related to claims in the action within such original jurisdiction that they form part of the same case or controversy under Article III.”1Office of the Law Revision Counsel. 28 USC 1367 – Supplemental Jurisdiction That language codifies the test the Supreme Court set out in United Mine Workers v. Gibbs: the federal and state claims must derive from a “common nucleus of operative fact.”2LII / Legal Information Institute. United Mine Workers of America v Gibbs
In practice, the claims need to grow out of the same events. A worker who sues an employer under a federal anti-discrimination statute and also raises a state-law wrongful termination claim based on the same firing satisfies the test easily. A worker who tries to tack on an unrelated state-law contract dispute from a separate business deal does not. Courts look at whether a reasonable person would expect the claims to be tried together, not whether the legal theories overlap.
Subsection (a) also reaches claims that bring new parties into the case through joinder or intervention. A defendant can file a third-party claim against someone new, and the court can hear it without independent federal jurisdiction, as long as it arises from the same core facts.1Office of the Law Revision Counsel. 28 USC 1367 – Supplemental Jurisdiction
The Diversity Carve-Out
Subsection (b) narrows things when the court’s original jurisdiction rests entirely on diversity of citizenship under 28 U.S.C. § 1332. In those cases, supplemental jurisdiction does not extend to claims by plaintiffs against parties brought in under Federal Rules of Civil Procedure 14, 19, 20, or 24, or to claims by persons seeking to join or intervene as plaintiffs under Rules 19 or 24, whenever exercising jurisdiction would be inconsistent with diversity requirements.1Office of the Law Revision Counsel. 28 USC 1367 – Supplemental Jurisdiction
The restriction is aimed at plaintiffs because they chose the forum. A plaintiff who files in federal court based on diversity cannot then use supplemental jurisdiction to bring in a non-diverse party and destroy the very basis for being there. Defendants are not restricted the same way. A defendant who files a third-party complaint under Rule 14 against a non-diverse party can still invoke supplemental jurisdiction, because the statute’s limits apply only to plaintiff-side claims.
Amount in Controversy Versus Complete Diversity
The Supreme Court drew the key line in Exxon Mobil Corp. v. Allapattah Services, Inc.: supplemental jurisdiction can rescue a claim that falls short of the $75,000 amount-in-controversy threshold, but it cannot rescue a claim that destroys complete diversity.3Supreme Court. Exxon Mobil Corp v Allapattah Services Inc When one plaintiff in a diversity action clears the amount requirement, the court can exercise supplemental jurisdiction over related claims from other plaintiffs who fall below $75,000. But if a non-diverse party enters the picture, the entire rationale for federal jurisdiction disappears.
The reasoning turns on how each requirement functions. The amount-in-controversy threshold is a claim-by-claim filter designed to keep trivial cases out of federal court. Diversity is an all-or-nothing structural requirement. If even one plaintiff shares citizenship with one defendant, there is no diversity jurisdiction over any claim, and supplemental jurisdiction has nothing to attach to.3Supreme Court. Exxon Mobil Corp v Allapattah Services Inc
When a Court Can Decline
Even when supplemental jurisdiction is available, subsection (c) gives judges discretion to turn it down on four grounds:1Office of the Law Revision Counsel. 28 USC 1367 – Supplemental Jurisdiction
- The state-law claim raises a novel or complex issue of state law. A dispute hinging on a recently enacted state statute with no appellate interpretation is a common example.
- The state-law claim substantially predominates over the federal claim in complexity, scope of discovery, or the relief sought.
- The court has dismissed all claims over which it had original jurisdiction. This is the most commonly invoked ground.
- Exceptional circumstances counsel against federal jurisdiction. Courts invoke this sparingly.
Section 1367(c) essentially codified the discretionary framework the Court set out in Gibbs, which said federal courts should avoid hearing state claims that substantially predominate over federal ones, “whether in terms of proof, of the scope of the issues raised, or of the comprehensiveness of the remedy sought.”2LII / Legal Information Institute. United Mine Workers of America v Gibbs Appellate review is for abuse of discretion, so trial judges have wide latitude.
What Happens After the Federal Claims Are Dismissed
When the federal anchor disappears under subsection (c)(3), courts weigh judicial economy, convenience, fairness, and comity before deciding whether to keep or release the remaining state-law claims. Timing matters more than anything else. If the federal claim is dismissed at the pleading stage or early in discovery, courts almost always let the state-law claims go, because little time and money have been invested and sending the parties to state court costs less than continuing a case that no longer belongs in federal court. The Supreme Court took that position in Carnegie-Mellon University v. Cohill.
Later-stage dismissals are a harder call. If the case has gone through extensive discovery, summary judgment briefing, or expert depositions, courts sometimes keep the case to avoid making the parties start over. The Third Circuit in Growth Horizons, Inc. v. Delaware County applied that reasoning, weighing “judicial economy, convenience, and fairness to the litigants” against the usual practice of dismissal.4Justia Law. Growth Horizons Inc v Delaware County
Remand Versus Dismissal
How a case entered federal court determines what happens next. If the case was originally filed in state court and removed, the federal court can remand the remaining state-law claims to the state court where they started. Carnegie-Mellon held that remand is generally preferable to dismissal in removed cases, because dismissal might leave a plaintiff unable to refile if a state statute of limitations has run during the federal detour. If the case was filed originally in federal court, remand is not an option; the court dismisses the supplemental claims without prejudice, and the plaintiff must refile in state court. That is where subsection (d)’s tolling rule matters most.
Tolling the State Statute of Limitations
Subsection (d) protects plaintiffs from being time-barred when supplemental claims get dropped. The limitations period “shall be tolled while the claim is pending and for a period of 30 days after it is dismissed unless State law provides for a longer tolling period.”1Office of the Law Revision Counsel. 28 USC 1367 – Supplemental Jurisdiction
Courts disagreed for years about what “tolled” meant. Some read it as merely a 30-day grace period after dismissal, with the state clock running the whole time the case sat in federal court. Others read it as stopping the clock entirely. The Supreme Court settled the question in Artis v. District of Columbia, holding that “tolled” means the limitations period is suspended for the entire time the claim is pending in federal court, plus 30 days after dismissal.5Justia Supreme Court Center. Artis v District of Columbia Under the grace-period reading, a plaintiff whose state claim had only a few months left when the federal case was filed might return to state court and find the deadline long past. Under the stop-the-clock reading now in force, the plaintiff gets back whatever time remained, plus 30 days.
The tolling protection also reaches any other claim in the same action that is voluntarily dismissed at the same time as, or after, the supplemental claim.1Office of the Law Revision Counsel. 28 USC 1367 – Supplemental Jurisdiction Even so, the 30-day window is a hard deadline. Missing it can permanently end a claim.
How Removal Interacts With § 1367
Removal follows a different rule. When a defendant removes a case that includes both federal-question claims and state-law claims outside supplemental jurisdiction, 28 U.S.C. § 1441(c) requires the district court to sever the claims it cannot hear and remand them to the state court from which the case was removed.6Office of the Law Revision Counsel. 28 USC 1441 – Removal of Civil Actions
This mandatory sever-and-remand is not the same as § 1367(c) discretion. Under § 1441(c), the court has no choice: claims that lack both original and supplemental jurisdiction go back automatically. The court’s discretion under § 1367(c) applies only to claims that qualify for supplemental jurisdiction but that the judge believes are better handled in state court. Which statute governs a particular claim decides whether the judge has a choice at all.