Supplemental Jurisdiction Guide
Supplemental jurisdiction under 28 U.S.C. Section 1367 allows federal courts to exercise jurisdiction over claims that do not independently qualify for federal subject matter jurisdiction, provided those claims are part of the same "case or controversy" as a claim that does. This doctrine prevents the inefficiency and inconvenience of requiring parties to litigate related claims in separate federal and state proceedings. It is the statutory codification and expansion of the earlier judge-made doctrines of pendent claim jurisdiction (United Mine Workers v. Gibbs) and ancillary jurisdiction.
Section 1367(a) establishes the broad grant: federal courts have supplemental jurisdiction over all claims that are "so related to claims in the action within [the court's] original jurisdiction that they form part of the same case or controversy under Article III." The Supreme Court has interpreted this "same case or controversy" language to mean claims sharing a "common nucleus of operative fact" with the jurisdictionally sufficient claim. This is a generous standard — if the claims arise from the same transaction, occurrence, or series of transactions and share significant factual overlap, supplemental jurisdiction generally reaches them.
Section 1367(b) contains critical exceptions that apply only in cases where the sole basis for original jurisdiction is diversity under Section 1332. In such cases, supplemental jurisdiction does not extend to claims by plaintiffs against persons made parties under Rules 14, 19, 20, or 24, or to claims by persons proposed to be joined as plaintiffs under Rule 19 or seeking to intervene as plaintiffs under Rule 24, if exercising jurisdiction would be inconsistent with the requirements of Section 1332. These exceptions prevent plaintiffs from using supplemental jurisdiction to circumvent the complete diversity requirement. Importantly, Section 1367(b) limits apply only to claims by plaintiffs, not by defendants — defendants' compulsory counterclaims, crossclaims, and third-party claims are not restricted.
Section 1367(c) provides discretionary grounds for declining supplemental jurisdiction: when the supplemental claim raises a novel or complex issue of state law, when the state-law claim substantially predominates over the federal claim, when the court has dismissed all claims over which it had original jurisdiction, or in exceptional circumstances. In practice, courts routinely decline supplemental jurisdiction under Section 1367(c)(3) when the federal claims are dismissed before trial, remanding the state-law claims to state court. Understanding when courts will and will not exercise discretion is critical for predicting litigation outcomes and for exam analysis.
Key Elements
- 1
Same Case or Controversy (Section 1367(a))
The supplemental claim must share a 'common nucleus of operative fact' with the claim that has independent federal jurisdiction. This means the claims arise from the same transaction, occurrence, or core set of facts.
- 2
Anchor Claim Requirement
There must be at least one claim in the action that independently satisfies federal subject matter jurisdiction (federal question or diversity). The supplemental claim 'piggybacks' on this anchor claim.
- 3
Section 1367(b) Exceptions (Diversity-Only Cases)
In cases where the sole basis for jurisdiction is diversity, supplemental jurisdiction does not extend to claims by plaintiffs against parties joined under Rules 14, 19, 20, or 24 if doing so would destroy complete diversity. Claims by defendants are not restricted.
- 4
Discretionary Declination (Section 1367(c))
Courts may decline supplemental jurisdiction if the claim raises a novel state-law issue, the state claim predominates, the anchor federal claims have been dismissed, or exceptional circumstances exist.
- 5
Amount in Controversy and Supplemental Jurisdiction
Under Exxon Mobil Corp. v. Allapattah Services, supplemental jurisdiction cures amount-in-controversy deficiencies in diversity cases: if one plaintiff meets the $75,000 threshold, additional plaintiffs with lower-value claims can piggyback via Section 1367.
Step-by-Step Analysis Flowchart
- Step 1: Identify the anchor claim — the claim that independently satisfies federal subject matter jurisdiction (federal question or diversity).
- Step 2: Identify the supplemental claim — the claim that does not independently satisfy federal jurisdiction.
- Step 3: Determine whether the supplemental claim shares a 'common nucleus of operative fact' with the anchor claim (Section 1367(a)).
- Step 4: If the claims arise from the same transaction, occurrence, or set of related events, the common-nucleus test is likely satisfied.
- Step 5: Check whether the case is based solely on diversity jurisdiction (not federal question). If yes, proceed to the Section 1367(b) analysis.
- Step 6: Under Section 1367(b), determine whether the supplemental claim is asserted by a plaintiff against a party joined under Rules 14, 19, 20, or 24, or by a person seeking to join as plaintiff under Rule 19 or intervene under Rule 24.
- Step 7: If Section 1367(b) applies, determine whether exercising supplemental jurisdiction would be inconsistent with Section 1332's requirements (i.e., would it destroy complete diversity?).
- Step 8: If Section 1367(b) does not bar the claim, consider whether the court should exercise discretionary declination under Section 1367(c).
- Step 9: Evaluate the four Section 1367(c) factors: novel state-law issue, state-law claim predominance, dismissal of all original jurisdiction claims, or exceptional circumstances.
- Step 10: Conclude whether supplemental jurisdiction permits the federal court to hear the claim.
Key Rules
- Section 1367(a) grants supplemental jurisdiction over all claims sharing a common nucleus of operative fact with the jurisdictionally sufficient anchor claim (codifying United Mine Workers v. Gibbs).
- Section 1367(b) exceptions apply only in diversity-only cases and only restrict claims by plaintiffs — defendants' compulsory counterclaims, crossclaims, and third-party claims are not affected.
- Supplemental jurisdiction cures amount-in-controversy deficiencies: additional plaintiffs can join a diversity case even if their individual claims are below $75,000, so long as one plaintiff meets the threshold (Allapattah).
- Courts routinely decline supplemental jurisdiction under Section 1367(c)(3) when all federal claims are dismissed before trial.
- The common nucleus of operative fact test is generous — claims need not be identical in their factual basis, only substantially overlapping.
- Supplemental jurisdiction extends to compulsory counterclaims (which by definition arise from the same transaction) even without independent jurisdictional basis.
Common Exam Patterns
Plaintiff brings a federal claim and a related state-law claim against the same defendant — straightforward Section 1367(a) supplemental jurisdiction over the state-law claim.
In a diversity case, plaintiff joins an additional defendant under Rule 20 who shares citizenship with plaintiff — tests Section 1367(b) restriction on plaintiff's claims.
A third-party defendant (Rule 14) asserts a claim against the original plaintiff — tests whether Section 1367(b) restricts this claim (it does not, because it is not a claim by a plaintiff).
Federal claims are dismissed on summary judgment, leaving only state-law claims — tests discretionary declination under Section 1367(c)(3).
Multiple plaintiffs sue under diversity, but some do not meet the $75,000 threshold — tests Allapattah supplemental jurisdiction over amount-deficient plaintiffs.
An intervening plaintiff under Rule 24 seeks to join a diversity case — tests Section 1367(b) restriction on intervenors whose presence would destroy complete diversity.
Landmark Cases
United Mine Workers of America v. Gibbs (1966)
Established the 'common nucleus of operative fact' test for pendent jurisdiction (the precursor to statutory supplemental jurisdiction), holding that a federal court can hear a related state-law claim when the facts substantially overlap.
Exxon Mobil Corp. v. Allapattah Services, Inc. (2005)
Held that Section 1367 permits supplemental jurisdiction over diversity plaintiffs who do not independently meet the amount-in-controversy requirement, resolving a circuit split on the issue.
Owen Equipment & Erection Co. v. Kroger (1978)
Held that a plaintiff cannot use ancillary jurisdiction (now supplemental jurisdiction) to assert a claim against a third-party defendant who destroys complete diversity — a principle codified in Section 1367(b).
Finley v. United States (1989)
Held that pendent-party jurisdiction (joining an additional party on a supplemental claim) required statutory authorization, prompting Congress to enact Section 1367 to fill the gap.
Tips for Success
- Section 1367(b) is the most tested part of supplemental jurisdiction. Memorize which Rules it references (14, 19, 20, 24) and remember it only restricts claims by plaintiffs in diversity-only cases.
- Always start with Section 1367(a) — establish the common nucleus of operative fact — before checking Section 1367(b) exceptions or Section 1367(c) declination.
- The distinction between claims by plaintiffs and claims by defendants under Section 1367(b) is critical: a defendant's compulsory counterclaim that destroys diversity is not barred by Section 1367(b).
- When all federal claims are dismissed before trial, courts almost always decline supplemental jurisdiction over remaining state-law claims under Section 1367(c)(3). Flag this on every exam where federal claims are dismissed.
- Allapattah applies only to amount-in-controversy deficiencies, not to diversity deficiencies. If a plaintiff destroys complete diversity, Section 1367(b) bars the claim.
- Think of supplemental jurisdiction as 'piggyback' jurisdiction: the supplemental claim rides on the anchor claim's jurisdictional coattails. No anchor, no piggyback.
- Do not confuse supplemental jurisdiction with removal. Supplemental jurisdiction is about adding claims; removal is about moving the case from state to federal court.