Subject Matter Jurisdiction — Determine whether federal subject matter jurisdiction exists - Bar Exam Uniform

SECTION 1

Historical Context & Constitutional Foundations

The concept of subject matter jurisdiction — the authority of a court to hear and decide a particular type of case — lies at the very foundation of the American federal system. Unlike courts of general jurisdiction in most state systems, federal courts are courts of limited jurisdiction, meaning they can only adjudicate disputes that fall within the powers granted to them by the Constitution and Congress. The Framers deliberately constrained federal judicial power, balancing the need for a national judiciary against the sovereignty of the states. This tension between federal and state authority has shaped the doctrine of subject matter jurisdiction from the earliest days of the Republic through modern practice.

1789 • Judiciary Act of 1789

Congress created the lower federal courts and established their original jurisdiction, including cases arising under federal law and certain diversity cases. Notably, the Act set a $500 amount-in-controversy requirement for diversity cases.

1806 • Strawbridge v. Curtiss

Chief Justice Marshall interpreted the diversity statute to require complete diversity — every plaintiff must be diverse from every defendant — a rule that persists today under 28 U.S.C. § 1332.

1875 • Federal Question Jurisdiction Broadened

Congress enacted general federal question jurisdiction, granting district courts original jurisdiction over civil actions arising under the Constitution, laws, or treaties of the United States, now codified at 28 U.S.C. § 1331.

1938 • Erie Railroad Co. v. Tompkins

The Supreme Court held that federal courts sitting in diversity must apply state substantive law, reinforcing that diversity jurisdiction does not create a separate body of federal common law and underscoring the federalism concerns animating jurisdictional limits.

2011 • Amount-in-Controversy Raised to $75,000

Congress most recently set the amount-in-controversy threshold at an amount exceeding $75,000, exclusive of interest and costs (28 U.S.C. § 1332(a)), reflecting ongoing legislative calibration of access to federal courts.

The central question this doctrine addresses is deceptively simple: Does this particular federal court have the constitutional and statutory authority to hear this particular case? Because subject matter jurisdiction cannot be waived by the parties and can be raised at any time — even on appeal — a failure to establish it is fatal to the litigation. Understanding the two primary bases for federal subject matter jurisdiction, federal question jurisdiction and diversity jurisdiction, is therefore essential to competent practice and a heavily tested area on the bar examination.

SECTION 2

Core Principles & Definitions

Federal subject matter jurisdiction rests on two primary statutory grants, each rooted in Article III, Section 2 of the Constitution. A plaintiff filing in federal court — or a defendant seeking to remove a case from state court — must demonstrate that the case satisfies the requirements of at least one of these grants. The following foundational principles govern the analysis.

Federal Question Jurisdiction (§ 1331)

District courts have original jurisdiction over all civil actions arising under the Constitution, laws, or treaties of the United States. The federal question must appear on the face of the plaintiff's well-pleaded complaint — anticipated federal defenses do not suffice.

Diversity Jurisdiction (§ 1332)

District courts have original jurisdiction over civil actions between citizens of different states (or between U.S. citizens and foreign citizens) where the amount in controversy exceeds $75,000, exclusive of interest and costs. Complete diversity is required under the statute.

Supplemental Jurisdiction (§ 1367)

When a district court has original jurisdiction over at least one claim, it may exercise supplemental jurisdiction over additional claims that form part of the same case or controversy under Article III — that is, claims sharing a common nucleus of operative fact.

Non-Waivable & Sua Sponte

Subject matter jurisdiction cannot be conferred by consent of the parties. A federal court has an independent obligation to confirm its own jurisdiction and must dismiss a case at any stage of the proceedings — including on appeal — if jurisdiction is lacking.

Burden of Proof

The party invoking federal jurisdiction bears the burden of establishing that jurisdiction exists. In an original filing, this is the plaintiff; in a removal action, it is the defendant. Ambiguities in the jurisdictional facts are generally construed against the party asserting jurisdiction.

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KEY TAKEAWAY

Think of federal subject matter jurisdiction like an admission ticket to a specific venue. A state court is a general-admission arena — nearly any case can walk through the door. A federal court, by contrast, is an exclusive event: you need a valid ticket (federal question or diversity) to get in. No ticket, no entry — and the bouncer (the court itself) can check your ticket at any time, even after you've been inside enjoying the show for months. Unlike personal jurisdiction, you can't simply charm your way past the door — consent of the parties is irrelevant.

SECTION 3

Visual Explanation — Federal SMJ Decision Tree

This decision tree traces the analysis a court (or litigator) should follow when determining whether federal subject matter jurisdiction exists. The left branch addresses federal question jurisdiction under § 1331, while the right branch covers diversity jurisdiction under § 1332 and supplemental jurisdiction under § 1367. If no path leads to a green box, the case must be dismissed.

The decision tree above illustrates the sequential nature of the jurisdictional inquiry. A practitioner should first ask whether the plaintiff's complaint affirmatively pleads a cause of action created by federal law — if so, the analysis under § 1331 is typically straightforward. When no federal question exists on the face of the complaint, the inquiry shifts to diversity of citizenship and the amount-in-controversy requirement. Finally, for claims that do not independently satisfy § 1331 or § 1332, the court may still exercise supplemental jurisdiction under § 1367 if those claims share a common nucleus of operative fact with a claim that does carry original jurisdiction. At every stage, the burden rests on the party asserting federal jurisdiction.

SECTION 4

How It Works — The Two Primary Bases

Federal Question Jurisdiction — 28 U.S.C. § 1331

Section 1331 grants district courts original jurisdiction over "all civil actions arising under the Constitution, laws, or treaties of the United States." The Supreme Court has long interpreted this language through the well-pleaded complaint rule, established in Louisville & Nashville Railroad Co. v. Mottley (1908). Under this rule, federal question jurisdiction exists only if a federal issue appears as part of the plaintiff's cause of action, not merely as an anticipated defense. Even if the defendant is certain to raise a federal constitutional defense, that alone does not create federal question jurisdiction if the underlying claim sounds in state law.

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The Mottley Rule in Action

In Mottley, the plaintiffs sued a railroad for breach of contract (a state-law claim), but anticipated that the railroad would defend on the ground that a federal statute prohibited honoring their free passes. The Supreme Court held that federal question jurisdiction was absent because the federal issue arose only as a defense, not as part of the plaintiffs' own claim. This remains one of the most heavily tested rules on the bar exam.

Two principal categories of cases satisfy the "arising under" requirement. First, a claim is a federal question when federal law creates the cause of action — for instance, a claim under 42 U.S.C. § 1983 for deprivation of constitutional rights, or a patent infringement action under 35 U.S.C. § 271. Second, under the narrower Grable doctrine (Grable & Sons Metal Products, Inc. v. Darue Engineering & Manufacturing, 2005), a state-law claim may "arise under" federal law if it necessarily raises a substantial, disputed federal issue that a federal forum may entertain without disturbing any congressionally approved balance of federal and state judicial responsibilities.

Diversity Jurisdiction — 28 U.S.C. § 1332

Diversity jurisdiction requires two independent showings: complete diversity of citizenship and an amount in controversy exceeding $75,000. Complete diversity means that no plaintiff may share citizenship with any defendant. For natural persons, citizenship is determined by domicile — the state where the individual is physically present with the intent to remain indefinitely. For corporations, citizenship exists in both the state of incorporation and the state where it has its principal place of business (the "nerve center" test from Hertz Corp. v. Friend, 2010). Diversity is assessed at the time the action is commenced.

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Amount-in-Controversy Tricks

The amount must exceed $75,000 — a claim for exactly $75,000 is insufficient. Courts apply a preponderance standard, and a plaintiff's good-faith allegation of the amount generally controls unless it appears to a legal certainty that the claim cannot meet the threshold. A single plaintiff may aggregate all claims against a single defendant to satisfy the amount, but multiple plaintiffs generally cannot aggregate their separate claims against a defendant.

SECTION 5

Detailed Breakdown — Citizenship, Supplemental Jurisdiction & Removal

Determining Citizenship

Party Type	Citizenship Rule	Key Details
Natural Person	State of domicile	Domicile = physical presence + intent to remain indefinitely. A person has only one domicile at a time.
Corporation	State of incorporation AND state of principal place of business	A corporation can be a citizen of two (or more) states. The nerve center (headquarters) determines the principal place of business.
Unincorporated Association	Citizenship of every member	LLCs, partnerships, and unions take on the citizenship of each member, making complete diversity harder to establish.
Class Action (CAFA)	Minimal diversity under 28 U.S.C. § 1332(d)	Only minimal diversity required (any class member diverse from any defendant). AIC must exceed $5,000,000 in aggregate.

Citizenship Rules for Diversity Jurisdiction

Supplemental Jurisdiction — 28 U.S.C. § 1367

Supplemental jurisdiction allows a federal court exercising original jurisdiction over one claim to hear additional claims that are so related as to form part of the same case or controversy under Article III. This "common nucleus of operative fact" test, derived from United Mine Workers v. Gibbs (1966), is codified in § 1367(a). However, § 1367(b) imposes critical limitations when original jurisdiction is based solely on diversity: the court may not exercise supplemental jurisdiction over claims by plaintiffs against parties joined under Rules 14, 19, 20, or 24 if doing so would destroy complete diversity. The purpose of this restriction is to prevent plaintiffs from circumventing the complete diversity requirement through artful joinder.

This diagram illustrates how § 1367's two subsections interact. Under § 1367(a), any claim sharing a common nucleus of operative fact with the jurisdictional anchor claim can qualify for supplemental jurisdiction. However, when the anchor is based solely on diversity jurisdiction, § 1367(b) restricts supplemental jurisdiction over claims by plaintiffs against parties joined under certain joinder rules.

Removal Jurisdiction — 28 U.S.C. § 1441

Removal is not an independent basis of jurisdiction but rather a procedural mechanism that allows a defendant to transfer a case from state court to the federal district court embracing the place where the state action is pending. A case is removable only if it could have been filed originally in federal court — that is, only if federal subject matter jurisdiction exists. An important wrinkle for diversity-based removal is the forum-defendant rule under § 1441(b)(2): a case may not be removed on the basis of diversity if any properly joined and served defendant is a citizen of the state in which the action was brought. The rationale is that the historical purpose of diversity jurisdiction — protecting out-of-state litigants from local bias — is not implicated when the defendant is already "at home" in the forum state.

SECTION 6

Worked Example — Analyzing Federal SMJ

Consider the following hypothetical: Paula, a citizen of New York, sues Delta Corp. (incorporated in Delaware with its principal place of business in Georgia) and Epsilon LLC (whose two members are citizens of Georgia and New Jersey) in federal court. Paula's complaint alleges a state-law breach-of-contract claim for $100,000 and a state-law negligence claim for $50,000 against both defendants.

Determining Federal Subject Matter Jurisdiction

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Step 1 — Check for Federal Question Jurisdiction (§ 1331)

Examine the face of the well-pleaded complaint. Paula's claims are for breach of contract and negligence, both arising under state law. No federal statute, constitutional provision, or treaty forms the basis of either cause of action. Accordingly, no federal question appears on the face of the complaint, and § 1331 is not satisfied.

No federal question jurisdiction.
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Step 2 — Check for Diversity Jurisdiction (§ 1332) — Citizenship

Identify the citizenship of each party. Paula is a citizen of New York. Delta Corp. is a citizen of both Delaware (state of incorporation) and Georgia (principal place of business). Epsilon LLC is an unincorporated association, so it takes the citizenship of each of its members: Georgia and New Jersey. Complete diversity requires that no plaintiff share citizenship with any defendant. Paula (NY) is diverse from Delta (DE, GA) and from Epsilon (GA, NJ). No overlap exists.

Complete diversity exists.
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Step 3 — Check Amount in Controversy

A single plaintiff may aggregate all claims against a single defendant. Against Delta, Paula has $100,000 + $50,000 = $150,000, which exceeds $75,000. Against Epsilon, she likewise has $100,000 + $50,000 = $150,000. Both exceed the statutory threshold. (Note: if the negligence claim were only against Epsilon for $30,000 total, Paula would still satisfy the amount against Delta at $150,000 and could potentially invoke supplemental jurisdiction over the Epsilon claim under § 1367.)

Amount in controversy exceeds $75,000 as to each defendant.
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Step 4 — Confirm Jurisdictional Requirements Are Met at Filing

Diversity is measured at the time the complaint is filed. Subsequent changes in domicile or party alignment generally do not destroy diversity (the "time-of-filing" rule). As long as Paula was domiciled in New York and the defendants' citizenships were as described at the moment the complaint was filed, the jurisdictional snapshot is complete.

Diversity jurisdiction is properly invoked under § 1332.
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Step 5 — Consider Supplemental Jurisdiction (if needed)

Here, both claims against both defendants independently satisfy § 1332, so supplemental jurisdiction is unnecessary. However, if Paula had an additional claim falling below the amount-in-controversy threshold against a diverse party, § 1367(a) could bring it within the court's jurisdiction provided the claims share a common nucleus of operative fact. Under Exxon Mobil Corp. v. Allapattah Services, Inc. (2005), supplemental jurisdiction may cure an amount-in-controversy deficiency for additional plaintiffs or additional claims in a diversity action, though § 1367(b) restricts its use to prevent plaintiffs from circumventing complete diversity.

Supplemental jurisdiction analysis not required on these facts, but always check.

SECTION 7

Comparing Federal Question and Diversity Jurisdiction

Feature	Federal Question (§ 1331)	Diversity (§ 1332)
Constitutional Basis	Art. III, § 2 — cases arising under federal law	Art. III, § 2 — controversies between citizens of different states
Key Test	Well-pleaded complaint rule: federal issue on face of plaintiff's claim	Complete diversity + amount in controversy exceeding $75,000
Amount in Controversy	Not required	Required: must exceed $75,000 (exclusive of interest and costs)
Substantive Law Applied	Federal law (the source of the claim)	State substantive law (Erie doctrine)
Removal Limitation	No forum-defendant bar; removable regardless of defendant's home state	Forum-defendant rule: no removal if any defendant is citizen of forum state
Policy Rationale	Uniformity of federal law interpretation; federal expertise	Protection of out-of-state litigants from local bias

Federal Question vs. Diversity Jurisdiction — Side-by-Side Comparison

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KEY TAKEAWAY

Federal question and diversity jurisdiction serve fundamentally different purposes within the federal system. Federal question jurisdiction ensures that cases implicating national law are heard by courts with expertise in that law, promoting uniform interpretation. Diversity jurisdiction, by contrast, provides a neutral forum for disputes between parties from different states, guarding against the risk — real or perceived — that a local court might favor its own citizens. Recognizing these distinct policy rationales will help you anticipate how courts resolve close jurisdictional questions and how examiners construct tricky fact patterns.

SECTION 8

Connection to Advanced Jurisdictional Doctrine

A solid grasp of subject matter jurisdiction is the gateway to more nuanced doctrinal areas that regularly appear on the bar examination and in practice. Three advanced topics deserve particular attention.

Basic Concept	Advanced Extension	Key Distinction
Complete diversity (§ 1332)	CAFA minimal diversity (§ 1332(d))	Class actions with 100+ members and aggregate AIC > $5M require only one class member diverse from one defendant.
Well-pleaded complaint rule	Complete preemption doctrine	In certain fields (ERISA, LMRA § 301, national bank acts), federal law so completely preempts state-law claims that the complaint is recharacterized as stating a federal cause of action, permitting removal.
Supplemental jurisdiction (§ 1367)	Discretionary decline under § 1367(c)	Courts may decline supplemental jurisdiction when the state claim raises novel/complex state law issues, the state claim predominates, all original-jurisdiction claims have been dismissed, or exceptional circumstances exist.
Removal (§ 1441)	Fraudulent joinder	A defendant may argue that a non-diverse party was fraudulently joined (no reasonable basis for the claim against them) and should be disregarded for diversity analysis, thereby permitting removal.

From Basic SMJ to Advanced Doctrinal Extensions

As you progress through civil procedure, keep in mind that subject matter jurisdiction intersects with virtually every other procedural topic: joinder of parties and claims, class actions, removal and remand, and even choice of law under the Erie doctrine. The analytical framework you develop here — systematically checking § 1331, § 1332, and § 1367 — forms a template you will return to repeatedly throughout practice and the bar examination. Mastering the basics ensures that the advanced extensions feel like natural elaborations rather than entirely new doctrines.

SECTION 9

Practice Problems

Question 1: CONCEPTUAL

A plaintiff files a state-law tort claim in federal court. The defendant plans to assert a defense based on the First Amendment to the U.S. Constitution. Does the anticipated constitutional defense give the federal court subject matter jurisdiction under § 1331? Explain why or why not.

Show answer

No. Under the well-pleaded complaint rule established in Louisville & Nashville Railroad Co. v. Mottley (1908), federal question jurisdiction exists only when a federal issue appears on the face of the plaintiff's complaint as part of the plaintiff's own cause of action. A plaintiff's state-law tort claim does not "arise under" federal law merely because the defendant intends to invoke a federal constitutional defense. The federal issue must be part of the claim, not the anticipated defense. Accordingly, § 1331 is not satisfied, and the court must look to another basis (such as diversity) for jurisdiction.

Question 2: BASIC APPLICATION

Alice, a citizen of California, sues Bob, a citizen of Nevada, for breach of contract seeking $80,000 in damages. She also asserts a claim against Carol, a citizen of California, for the same breach, seeking $40,000. Alice files in federal district court. Does the court have diversity jurisdiction? Identify all issues.

Show answer

The court does not have diversity jurisdiction over the entire action. Under § 1332, complete diversity requires that no plaintiff share citizenship with any defendant. Here, Alice (California) and Carol (California) are co-citizens — but the question presents Carol as a defendant, not a plaintiff. If Carol is a defendant, then Alice (CA) shares citizenship with Carol (CA), destroying complete diversity under Strawbridge v. Curtiss. The amount in controversy against Bob ($80,000) exceeds $75,000, but the jurisdictional defect in diversity (Alice and Carol share California citizenship) is fatal to the entire diversity analysis. As for Carol's claim amount of $40,000, even if diversity were otherwise satisfied, this would fall below the threshold, though supplemental jurisdiction might cure it under Allapattah — but that issue never arises because complete diversity is absent in the first place.

Question 3: INTERMEDIATE

MedTech LLC has two members: one is domiciled in Texas, the other in Florida. MedTech sues PharmaCorp, incorporated in Delaware with its principal place of business in Texas, in federal court for state-law breach of a supply contract worth $200,000. Does diversity jurisdiction exist? What if MedTech also asserts a federal patent infringement claim?

Show answer

On the diversity analysis: MedTech LLC is an unincorporated association, so its citizenship is determined by the citizenship of each of its members — Texas and Florida. PharmaCorp is a citizen of Delaware (incorporation) and Texas (principal place of business). Because MedTech's Texas member shares citizenship with PharmaCorp (also a Texas citizen), complete diversity is destroyed, and § 1332 jurisdiction fails despite the amount exceeding $75,000. However, if MedTech also asserts a federal patent infringement claim, that claim arises under federal law (35 U.S.C. § 271), satisfying § 1331 federal question jurisdiction. The court would then have original jurisdiction over the patent claim and could exercise supplemental jurisdiction over the state-law breach-of-contract claim under § 1367(a), provided the claims share a common nucleus of operative fact. Since the anchor is federal question (not diversity), § 1367(b) limitations do not apply.

Question 4: APPLIED

Defendant removes a case from New York state court to the Southern District of New York. The complaint alleges a state-law products liability claim for $100,000. The plaintiff is a citizen of New York. The defendant is a corporation incorporated in New Jersey with its principal place of business in New York. The defendant argues federal diversity jurisdiction supports removal. Should the federal court remand? Identify all relevant rules.

Show answer

Yes, the court should remand for at least two independent reasons. First, complete diversity may be lacking: the plaintiff is a citizen of New York, and the defendant corporation is a citizen of both New Jersey (incorporation) and New York (principal place of business under the Hertz nerve center test). Because the defendant is a citizen of the same state as the plaintiff (New York), complete diversity is destroyed under § 1332. Second, even if diversity existed, § 1441(b)(2) — the forum-defendant rule — bars removal of a case on diversity grounds when any properly joined and served defendant is a citizen of the state where the action was originally filed. Here, the defendant is a citizen of New York and the action was filed in New York, so the forum-defendant rule independently bars removal. The court must remand under 28 U.S.C. § 1447(c) for lack of subject matter jurisdiction.

Question 5: CRITICAL THINKING

A plaintiff files a state-law wrongful termination claim in federal court, alleging that she was fired in violation of her employment contract. However, the employment contract contains a clause requiring disputes to be resolved under procedures specified in a federal statute (the Labor Management Relations Act, 29 U.S.C. § 185). The defendant argues the claim is completely preempted and thus arises under federal law. Analyze whether federal question jurisdiction exists, discussing both the well-pleaded complaint rule and the complete preemption doctrine. How does this scenario differ from Mottley?

Show answer

This scenario tests the tension between the well-pleaded complaint rule and the complete preemption doctrine. Under the well-pleaded complaint rule, the plaintiff's wrongful termination claim appears to be a state-law contract claim, and federal jurisdiction would normally be absent — much like in Mottley, where the federal issue appeared only as an anticipated defense. However, the complete preemption doctrine, recognized in cases like Avco Corp. v. Aero Lodge No. 735 (1968), provides a narrow exception. When Congress has so completely preempted a field that any claim within its scope is necessarily federal in character, the plaintiff's state-law claim is recharacterized as arising under federal law regardless of how the plaintiff pleads it. LMRA § 301 is one of the recognized areas of complete preemption: claims substantially dependent on the interpretation of a collective bargaining agreement are treated as federal claims. If the plaintiff's employment contract is a CBA governed by § 301, her wrongful termination claim would be recharacterized as a federal claim, conferring § 1331 jurisdiction and permitting removal. This differs from Mottley because complete preemption transforms the nature of the plaintiff's claim itself, rather than merely raising a federal defense. The key analytical question is whether the state-law claim is truly independent of the CBA or whether resolution requires interpreting CBA terms — only in the latter case does complete preemption apply.

SUMMARY

Summary — Federal Subject Matter Jurisdiction

Summary

Federal courts are courts of limited jurisdiction, and every case filed in or removed to federal court must satisfy subject matter jurisdiction. The two principal bases are federal question jurisdiction under 28 U.S.C. § 1331, which requires a federal issue on the face of the well-pleaded complaint, and diversity jurisdiction under § 1332, which demands complete diversity of citizenship and an amount in controversy exceeding $75,000. When neither basis independently applies, supplemental jurisdiction under § 1367 may extend the court's power to related claims sharing a common nucleus of operative fact, though § 1367(b) limits plaintiff claims in diversity-only cases.

Critical rules to remember: subject matter jurisdiction cannot be waived by the parties and can be raised at any stage, even on appeal. The party invoking federal jurisdiction bears the burden of proof. For diversity purposes, natural persons are citizens of their domicile, corporations hold dual citizenship (incorporation and nerve center), and unincorporated entities take the citizenship of every member. On the bar exam, always apply the framework methodically: check § 1331 first, then § 1332, then § 1367, and finally consider removal and the forum-defendant rule if the case was originally filed in state court.