Concept
Related Federal Court Limits
Diversity jurisdiction
Related Federal Court Limits
Satisfying the diversity statute tells a federal court that it has authority to decide this kind of dispute. It does not tell the court that this defendant can be forced to appear there, that this district is the right place for the trial, or which state's law will decide the merits. Those are separate questions with separate sources, and a case can clear diversity and still fail one of them. The material below places diversity beside its neighbors. The cases mentioned here are taught in other readings and appear only for orientation.
Diversity Versus Personal Jurisdiction
Subject-matter jurisdiction is a court's authority over the nature of the case and the type of relief sought, while personal jurisdiction is a court's power to bring a particular person into its adjudicative process.1 The first question looks at the kind of dispute and the status of the parties as the statute defines them. The second looks at the defendant's relationship to the place where the court sits. Because the two ask about different things, satisfying one proves nothing about the other. Federal pleading rules reflect the first inquiry, since a complaint must contain a short and plain statement of the grounds for jurisdiction, and a diversity complaint should allege each party's citizenship rather than mere residence.2
The two inquiries also differ in who controls them. Subject-matter jurisdiction cannot be waived, so a party or the court may raise it before, during, or after adjudication in the district court.3 Personal jurisdiction protects the defendant and can be waived. In a diversity case the federal court usually asks whether a court of the state where it sits could reach the defendant under that state's long-arm statute and the Fourteenth Amendment Due Process Clause.4 A federal court in Boston may therefore exercise personal jurisdiction over a defendant only if a Massachusetts court could. The federal statute does not widen that reach. A diversity plaintiff has to clear both hurdles.
A matched pair shows which fact decides each question. Suppose Paula, a California citizen, sues David, an Illinois citizen, in federal court in California over an Illinois fireworks fire, claiming more than $75,000 under state tort law. Diversity is complete and the amount is met, so subject-matter jurisdiction exists. David has never set foot in California, so no minimum contacts support personal jurisdiction there, and the court cannot hear the case.5 Now move the same suit to Illinois state court with only $50,000 claimed. State courts are not bound by the $75,000 requirement, and David lives in Illinois and caused the fire there, so both kinds of jurisdiction exist.6 The state-court forum is available because diversity jurisdiction is concurrent. A plaintiff relying on it could have sued in an appropriate state court instead.7
Venue is a third filter. Suppose Powers, a Connecticut citizen, sues Doris, a New Jersey citizen, in Buffalo for more than $75,000 over a Manhattan car accident. The court would have diversity jurisdiction and, because the claim arises from Doris's New York conduct, personal jurisdiction too. Yet Buffalo is four hundred miles from the accident and from both parties. Congress passed venue statutes to keep cases out of courts that have power but no real connection to the dispute.8
State Law in Diversity Cases
Once a federal court has jurisdiction in diversity, a separate question arises: what law decides the merits? A federal court sitting in diversity applies state substantive law and federal procedural law. The reason follows from why the jurisdiction exists. Congress offered out-of-state litigants another tribunal, not another body of law, so the accident of diverse citizenship should not change who wins. The decisions that draw the line between substance and procedure, beginning with the Erie line, are taught in a separate reading on choice of law in federal court and are named here only so that the reader knows where this topic leads.
A short example shows the division of labor. Suppose a Texas citizen sues an Oklahoma citizen in federal court for breach of a contract governed by state law. Diversity supplies the court's power to hear the claim, while state contract law supplies the rule of decision. The Federal Rules of Civil Procedure govern how the case is pleaded, discovered, and tried. If the same plaintiff sued on a federal statute, state law would no longer supply the rule of decision.
Peripheral Authorities
Two decisions in the related materials bear on this reading only as constitutional background. In Flast v. Cohen the Court described the jurisdiction of the federal courts as defined and limited by Article III, which restricts the judicial power to cases and controversies.10 In Massachusetts v. EPA the Court accepted that a petitioner must have standing under Article III before the Court may reach the merits, even where the underlying question is important.11 Standing therefore operates as its own gate, separate from the statutory diversity requirements, and a diversity case also needs a plaintiff with a real stake in the dispute.
Interpleader offers a last point of comparison. Under Rule 22, a stakeholder who wants to deposit disputed property with the court must meet ordinary diversity: more than $75,000 at stake and citizenship diverse between the stakeholder and the claimants. The federal interpleader statute asks instead that the claimants be diverse among themselves and that the fund be worth at least $500.12 Interpleader is taught in its own reading, and the contrast is worth recalling only because it shows that a different jurisdictional statute can change the diversity arithmetic.
Diversity Versus Personal Jurisdiction
Clearing the diversity statute answers one question about a federal court's power, and a second question remains untouched. Subject-matter jurisdiction is a court's authority over the nature of the case and the type of relief sought, while personal jurisdiction is the court's power to bring a particular defendant into the proceeding and bind that defendant to the result.13 The first inquiry looks at the kind of dispute and at the parties' citizenship as § 1332 defines it, together with the amount claimed. The second looks at the relationship between the defendant and the place where the court sits. Because the two inquiries examine different facts, satisfying one says nothing about the other.
The reasons for keeping them apart follow from whom each rule protects. Subject-matter jurisdiction allocates power among court systems, so the parties cannot create it by agreement or surrender it by silence, and any party or the court itself may raise a defect before, during, or after adjudication in the district court.14 Personal jurisdiction protects the individual defendant against being hauled into a distant forum, and for that reason the defendant can waive it. The constitutional test for a defendant who is not present in the forum asks whether the defendant has such minimum contacts with it that the suit does not offend "traditional notions of fair play and substantial justice."15 That test is taught in the personal jurisdiction reading, and here it matters only as the second hurdle a diversity plaintiff must clear.
In most diversity cases the federal court borrows the forum state's answer to that second question. A federal court may exercise personal jurisdiction over a defendant if a court of the state where it sits could do so under that state's long-arm statute and the Fourteenth Amendment Due Process Clause.16 The federal diversity statute does not widen that reach. Burger King Corp. v. Rudzewicz illustrates the point: the franchisor invoked diversity under § 1332(a), yet the contested issue was whether a Michigan franchisee had enough contact with Florida for the Florida federal court to reach him.17 A diversity plaintiff therefore has to satisfy two separate requirements, and a failure on either one ends the case in that court.
A matched pair of invented cases shows which fact controls each inquiry. Suppose Paula, a California citizen, sues David, an Illinois citizen, in federal court in California for more than $75,000 under state tort law, alleging that David's fireworks set her Illinois house on fire. Citizenship is diverse and the amount is met, so subject-matter jurisdiction exists. David has never set foot in California, so no contacts support personal jurisdiction there, and the court cannot hear the case.18 Now change two facts. Paula files in Illinois state court and claims only $50,000. The $75,000 floor does not limit state courts, and David both lives in Illinois and caused the fire there, so the state court has subject-matter and personal jurisdiction alike.19 The first filing fails on the defendant's contacts and the second succeeds on them, even though the diversity analysis favored Paula only in the first.
State Law in Diversity Cases
Clearing § 1332 tells a federal court that it may hear the dispute, but it does not say what rules will decide it. In a diversity case the federal court applies state substantive law, such as the law of torts or contracts, and conducts its proceedings under the Federal Rules of Civil Procedure.21 The source of the first half of that rule is Erie Railroad Co. v. Tompkins, which held that outside matters governed by the Constitution or Acts of Congress, the law applied in any case is the law of the state, and that there is no federal general common law.22 The reason follows from why the jurisdiction exists. Diversity was conferred to guard out-of-state litigants against bias in state courts. Under the older practice of federal "general law," the rights a litigant enjoyed varied with whether suit was brought in state or federal court, and the nonresident got to choose the forum.23 A second tribunal, rather than a second body of law, is all that diversity was meant to supply.
The line between substance and procedure is where the difficulty lies, and a separate reading on the Erie doctrine takes it up; the cases are named here only to show where the topic leads. Guaranty Trust Co. v. York asked whether disregarding a state rule would significantly change the result compared with a state-court suit on the same claim.24 Klaxon Co. v. Stentor Electric Manufacturing Co. extended the same reasoning to conflict-of-laws rules, so the federal court follows those of the state where it sits.25 Hanna v. Plumer addressed a direct clash with a Federal Rule of Civil Procedure and tied the analysis to the twin aims of discouraging forum-shopping and avoiding inequitable administration of the laws.26 Semtek International Inc. v. Lockheed Martin Corp. held that the claim-preclusive effect of a federal diversity judgment is governed by a federal rule that borrows the law of the state where the federal court sits.27
A matched pair shows the division of labor. Suppose a Texas citizen sues an Oklahoma citizen in federal court for more than $75,000 over a car collision in Oklahoma. Diversity supplies the court's power to hear the claim, and Oklahoma negligence law decides whether the defendant is liable. No federal common law of torts exists to displace it, while the Federal Rules control how the complaint is pleaded and how discovery proceeds.28 Now change the basis of the suit. If the plaintiff sues under a federal statute, jurisdiction rests on the federal nature of the claim, and federal sources supply the substantive rule of decision, so no question of borrowing state law arises in the ordinary way.29 What moved the answer was the ground of jurisdiction, because Erie operates chiefly where the only link to federal court is the parties' citizenship.
Peripheral Authorities
A few decisions in the related materials touch diversity only at the edges, and they help most as contrasts. In Martin v. Hunter's Lessee the Court reasoned that the Constitution contemplated cases within the federal judicial power arising in state courts in the ordinary exercise of their jurisdiction, and that state judges must decide according to federal law as well as state law.31 That reasoning supports a point about diversity. A state court is fully competent to hear a case between citizens of different states, so diversity jurisdiction adds a second forum to the plaintiff's options. Because the federal court is an alternative to a state court that could already decide the case, the statute limits the federal forum through the citizenship, amount, and timing requirements covered earlier in this reading.
The other relevant decisions show diversity being absent or being only one of several gates. In Ex parte Young the Court observed that no one claimed jurisdiction on the ground of diversity of citizenship, and that the claim would have been unfounded in fact if made, so the case could proceed only because it presented federal questions.32 A case that fails the diversity count is therefore not necessarily lost in federal court, but it needs some other statutory basis. Standing is a separate requirement that applies to every federal case. It asks whether the party seeking relief is a proper party to request adjudication, which is a question about the party and not about the issue.33 A diversity plaintiff with complete diversity and a sufficient amount must still have a personal stake in the outcome.