What You'll Learn

  • The anchor claim
  • Section 1367(a)
  • Section 1367(b) limits
  • Section 1367(c) discretion
  • Exxon and amount in controversy
  • Tolling and exam structure

Educational information only; not legal advice. This article is a general study aid and should be checked against current authority and course materials.

Federal lawsuits often contain a mix of claims. One claim may independently belong in federal court while another does not. Supplemental jurisdiction asks whether the second claim is close enough to accompany the first, whether Congress has barred it in a diversity case, and whether the court should nevertheless decline it.

1. Start with an Anchor Claim

Supplemental jurisdiction cannot create a federal case from nothing. The action needs at least one claim within the district court's original jurisdiction, such as a federal claim under § 1331 or a diversity claim under § 1332.

Original Jurisdiction

Identify the federal-question, diversity, or other anchor claim. >

§ 1367(a)

Ask whether the additional claim forms part of the same Article III case or controversy. >

§ 1367(b)-(c)

Check diversity limits and discretionary reasons to decline.

2. Section 1367(a): Same Case or Controversy

Section 1367(a) generally extends jurisdiction to claims so related to the anchor claim that they form part of the same case or controversy under Article III. Courts commonly use the United Mine Workers v. Gibbs formulation: the claims share a common nucleus of operative fact such that a plaintiff would ordinarily be expected to try them together.

Key Takeaway

Look for overlapping events, witnesses, documents, injuries, transactions, or proof. Merely sharing a legal topic or involving the same parties is not enough if the factual cores are separate. Section 1367(a) can include claims involving additional parties, subject to the remaining statutory limits.

3. Section 1367(b): Diversity-Only Plaintiff Limits

Section 1367(b) applies when original jurisdiction is founded solely on diversity. It prevents specified plaintiff-side uses of supplemental jurisdiction that would be inconsistent with § 1332.

The statute restricts claims by plaintiffs against persons made parties under Rules 14, 19, 20, or 24, and specified claims by persons seeking to join as plaintiffs under Rule 19 or intervene as plaintiffs under Rule 24, when exercising jurisdiction would conflict with diversity requirements.

Common Mistake

Do not say that § 1367(b) bars every claim involving Rules 14, 19, 20, or 24. The text is targeted, primarily at claims by plaintiffs in diversity-only actions. Claims asserted by defendants are often treated differently.

Key Takeaway

A diverse plaintiff sues a diverse defendant. The defendant impleads a third-party defendant under Rule 14. The plaintiff then wants to assert a state-law claim against that third-party defendant, who shares the plaintiff's citizenship. Although the claims may share a common nucleus, § 1367(b) ordinarily prevents the plaintiff from using supplemental jurisdiction to evade complete diversity through a claim against a Rule 14 party.

4. Section 1367(c): The Court May Decline

Even when subsection (a) grants jurisdiction and subsection (b) does not remove it, the court may decline under § 1367(c) when: 1. the claim raises a novel or complex issue of state law; 2. the state claim substantially predominates over claims within original jurisdiction; 3. the court has dismissed all claims over which it had original jurisdiction; or 4. exceptional circumstances provide other compelling reasons.

The word "may" matters. The court balances economy, convenience, fairness, and comity rather than treating every listed condition as automatic dismissal.

5. Exxon and Smaller Claims

In a diversity action, Exxon Mobil Corp. v. Allapattah Services, Inc. permits supplemental jurisdiction over certain related claims by additional completely diverse plaintiffs who do not individually meet the amount in controversy, so long as at least one plaintiff's claim does and § 1367(b) does not bar the additional claim. Exxon does not permit a nondiverse plaintiff or defendant to enter an ordinary diversity case. Complete diversity remains mandatory.

6. Tolling Under Section 1367(d)

When a state-law claim is pursued under supplemental jurisdiction and later dismissed, § 1367(d) protects the state limitations period while the claim is pending in federal court and for at least 30 days after dismissal, unless state law provides a longer period. This protection helps a claimant refile in state court.

7. Worked Hypothetical

Key Takeaway

A federal employee-discrimination claim and a state contract claim both arise from the same termination meeting, the same compensation agreement, and the same witnesses. The federal claim is later dismissed on summary judgment. The federal claim originally supplies § 1331 jurisdiction. The state claim likely satisfies § 1367(a) because the factual cores overlap. Section 1367(b) does not apply because original jurisdiction was not founded solely on diversity. After dismissal of the federal claim, the court may decline the state claim under § 1367(c)(3), but dismissal is discretionary rather than automatic.

8. Exam Checklist

  1. Identify the anchor claim and its original jurisdictional basis. 2. Apply the common-nucleus test under § 1367(a). 3. If the anchor is solely diversity, read § 1367(b) by claimant, target party, and joinder rule. 4. Apply each relevant § 1367(c) ground. 5. State whether dismissal would be with or without prejudice and consider § 1367(d) tolling.

Key Takeaway

The additional claim falls within § 1367(a) because it shares a common nucleus of operative fact with the anchor claim. Because original jurisdiction is [or is not] founded solely on diversity, § 1367(b) [does or does not] apply. The court may still decline under § 1367(c) if a listed ground and the discretionary factors support doing so.

Primary Authorities

  • 28 U.S.C. § 1367.

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

  • Owen Equipment & Erection Co. v. Kroger, 437 U.S. 365 (1978).

  • Exxon Mobil Corp. v. Allapattah Services, Inc., 545 U.S. 546 (2005).

Exam-ready conclusion

Supplemental jurisdiction is a three-stage analysis: grant under subsection (a), diversity limits under subsection (b), and discretion under subsection (c). Skipping any stage turns a manageable statute into confusion.