Adding Parties to a Federal Lawsuit: Joinder, Intervention, Impleader, and Interpleader

Summary. Federal lawsuits rarely stay two-sided, and the rules that decide who else may be pulled in, who may push in, and who must be present are among the most consequential and least studied in civil procedure. This article explains each party-structuring device in the Federal Rules: joinder of claims under Rule 18, crossclaims and counterclaim joinder under Rule 13, permissive joinder and severance under Rules 20 and 21, required joinder under Rule 19, impleader under Rule 14, interpleader under Rule 22 and 28 U.S.C. section 1335, intervention under Rule 24, and substitution under Rule 25. It tells the stories behind the leading Supreme Court cases, from Provident Tradesmens and Tashire to Owen Equipment, Pimentel, Laroe Estates, Berger, and Cameron. It then lays the jurisdictional overlay on top: the section 1367(b) limits in diversity cases, the complete-diversity trap, post-removal joinder under section 1447(e), fraudulent joinder, personal jurisdiction and the 100-mile bulge, and the patent joinder statute. Open questions and circuit splits, practical implications for plaintiffs, defendants, and nonparties, an extended worked example built around a warehouse fire, common mistakes, an FAQ, and takeaways close the article.

In January 1972, the boom of a steel crane came too close to a high-voltage line and electrocuted a man named James Kroger. His widow, an Iowa citizen, sued the Nebraska power company in federal court in Nebraska on diversity. The power company brought in the crane owner as a third-party defendant, the widow added a direct claim against the crane owner, and the power company then won summary judgment and left the case. On the third day of trial, it came out that the crane owner's principal place of business was in Iowa, the same state as the widow. The jury found for her anyway. Six years after the accident, the Supreme Court held that the federal court had never had power to hear her claim against the crane owner at all. Owen Equipment & Erection Co. v. Kroger, 437 U.S. 365 (1978).

That is the lesson of party practice in one story. The Federal Rules make it easy to add people to a lawsuit. They do not make it easy to add people a federal court can actually adjudicate claims against, and the gap between those two things is where verdicts are vacated, removals are remanded, and limitations periods quietly expire. Every time a party is added, dropped, substituted, or allowed in, four separate questions have to be answered: does a rule permit it, does the court have subject-matter jurisdiction over the new claims, does the court have personal jurisdiction (and proper venue) over the new party, and is it a good idea?

This article works through those questions for each of the party-structuring devices, using the cases that built the doctrine.

The short answer

Rule 18 joins claims, Rule 20 joins parties, and Rule 21 fixes mistakes. A party may join any claims it has against an opposing party. Multiple plaintiffs or defendants may be joined if the claims arise from the same transaction, occurrence, or series of them and share a common question. Misjoinder is never a ground to dismiss the whole action; the remedy is severance or dropping a party.
Rule 19 is pragmatic, not mechanical. A person is required if complete relief is impossible without it or if its absence threatens its interests or exposes a party to inconsistent obligations. If a required person cannot be joined, the court weighs four equitable factors before dismissing. Joint tortfeasors are not required parties. Temple v. Synthes Corp., 498 U.S. 5 (1990).
Rule 14 is for derivative liability only. A defendant may implead a nonparty "who is or may be liable to it for all or part of the claim against it." It may not implead someone just to point the finger. File within 14 days of the original answer or get leave.
Interpleader comes in two forms. Rule 22 uses ordinary jurisdiction, venue, and service. The statute, 28 U.S.C. § 1335, needs only two adverse claimants of diverse citizenship and $500, and brings nationwide service and an injunction under 28 U.S.C. § 2361. State Farm Fire & Casualty Co. v. Tashire, 386 U.S. 523 (1967).
Intervention of right needs four things: a timely motion, a protectable interest, practical impairment, and inadequate representation, a burden the Supreme Court calls "minimal." Trbovich v. United Mine Workers, 404 U.S. 528 (1972). An intervenor seeking relief different from the existing parties' needs its own standing. Town of Chester v. Laroe Estates, Inc., 581 U.S. 433 (2017).
Diversity cases are where joinder goes wrong. 28 U.S.C. § 1367(b) withholds supplemental jurisdiction over a plaintiff's claims against parties joined under Rules 14, 19, 20, or 24 when those claims would break complete diversity. After removal, adding a nondiverse defendant forces a choice between denying joinder and remanding under 28 U.S.C. § 1447(e).
Personal jurisdiction does not come free. Parties joined under Rule 14 or Rule 19 can be served within 100 miles of the courthouse under Rule 4(k)(1)(B), but everyone else needs an ordinary basis, and each plaintiff's claim needs its own connection to the forum. Bristol-Myers Squibb Co. v. Superior Court, 582 U.S. 255 (2017).

Why party structure is a strategic decision, not a clerical one

Party structure decides who is bound by the judgment, who pays it, and who shows up at trial. A plaintiff who sues one manufacturer and leaves the installer out gets a simpler trial and an empty chair for the defense to blame. A defendant who impleads its supplier converts a two-party fight into a three-way one in which the supplier may help the plaintiff. An insurer that interpleads its limits ends its exposure to competing claimants but invites the court to supervise how the money is split. A nonparty that intervenes gets a voice and a right to appeal, and in exchange it is bound by the result.

Preclusion is the hidden variable. A judgment generally binds only parties and those in privity with them. The Supreme Court rejected the idea that nonparties are bound simply because they knew about a suit and could have intervened, Martin v. Wilks, 490 U.S. 755 (1989), and it rejected "virtual representation" as a general basis for nonparty preclusion, Taylor v. Sturgell, 553 U.S. 880 (2008). (Congress later created a narrow exception for employment consent decrees in Title VII.) The practical consequence is that if a party wants a judgment that settles a question for everyone affected, it usually has to bring everyone affected into the case. Rules 19, 22, and 24 exist largely to manage that problem.

For the jurisdictional foundations that every joinder question rests on, see Civil Procedure Toolkit: Pleadings, Jurisdiction, Preclusion, and Deadlines. For the step-by-step mechanics of asking to come into a case or keeping someone out, see the companion guide, Intervening in a Federal Case or Opposing Intervention: A Practical Guide.

A short history: from "indispensable" parties to pragmatism

The common law was hostile to multiparty litigation. Joinder of plaintiffs required a joint right; joinder of defendants required joint liability. Equity was more generous and developed the vocabulary of "necessary" and "indispensable" parties, a vocabulary that hardened in the nineteenth century into categories that seemed to answer questions by labeling them. The original Federal Rules of 1938 kept much of that language.

The 1966 amendments were the turning point. The Advisory Committee rewrote Rule 19 to replace the old categories with a functional inquiry: who needs to be here, can they be brought here, and if not, should the case go on without them? It rewrote Rule 24(a) to tie intervention of right to practical impairment of an interest rather than to whether the intervenor would be formally bound. It rewrote Rule 23 at the same time, which is no coincidence: all three rules address the same question of how far one lawsuit can reach. The 2007 restyling removed the word "indispensable" from Rule 19 altogether, though lawyers and judges still use it. The Supreme Court has said the restyling changed nothing of substance. Republic of Philippines v. Pimentel, 553 U.S. 851 (2008).

Supplemental jurisdiction has its own history. United Mine Workers v. Gibbs, 383 U.S. 715 (1966) let federal courts hear state claims that formed one constitutional "case" with a federal claim. Courts extended the idea to "ancillary" jurisdiction over impleader, counterclaims, and intervention. Then Finley v. United States, 490 U.S. 545 (1989) held that pendent-party jurisdiction needed congressional authorization, and Congress answered the next year with 28 U.S.C. § 1367, which codified supplemental jurisdiction and, in subsection (b), wrote the Owen Equipment limit into the statute.

Joining claims: Rules 18 and 13

Fed. R. Civ. P. 18(a) lets a party asserting a claim join "as many claims as it has against an opposing party," related or not. Rule 18 is about permission, not jurisdiction: each claim still needs its own basis for subject-matter jurisdiction, and unrelated state claims against a nondiverse opponent will usually fail under § 1367(a) because they do not form part of the same case or controversy. Rule 18(b) adds a useful clarification: a plaintiff may join a claim that depends on another claim being resolved first, such as a creditor's claim for money and a claim to set aside a fraudulent transfer of the debtor's assets.

Fed. R. Civ. P. 13 does the same work for defending parties. Compulsory counterclaims under Rule 13(a) must be asserted or lost. Crossclaims under Rule 13(g) run between coparties, must arise out of the transaction or occurrence that is the subject of the original action or a counterclaim, and may include a claim that the coparty "is or may be liable to the crossclaimant for all or part of a claim asserted in the action against the crossclaimant." Crossclaims are optional; failing to assert one does not forfeit it. Rule 13(h) is the bridge to party joinder: it lets a counterclaimant or crossclaimant add new parties, governed by Rules 19 and 20. A defendant who has a counterclaim against the plaintiff and the plaintiff's parent company can use Rule 13(h) to bring the parent in as a counterclaim defendant, which is cleaner than a Rule 14 third-party complaint because the parent's liability is direct, not derivative.

Counterclaim drafting, including the compulsory-permissive distinction, is covered in Answering a Federal Complaint: Denials, Affirmative Defenses, Counterclaims, and Judgment on the Pleadings.

Permissive joinder and severance: Rules 20 and 21

The test

Fed. R. Civ. P. 20(a) has two prongs for both plaintiffs and defendants. The claims must (1) arise "out of the same transaction, occurrence, or series of transactions or occurrences," and (2) present "any question of law or fact common to all." Relief can be joint, several, or in the alternative, which lets a plaintiff who does not know which of two defendants injured her sue both and let the jury sort it out.

The classic reading of "series of transactions" comes from Mosley v. General Motors Corp., 497 F.2d 1330 (8th Cir. 1974). Ten employees sued their employer and union, each alleging race and sex discrimination in different decisions affecting different people. The district court thought the claims were too individualized to join. The Eighth Circuit reversed: the employees alleged a company-wide policy of discrimination, and claims arising from a common policy are "logically related" enough to be a series of transactions. Mosley's "logical relationship" test, borrowed from the compulsory-counterclaim cases, is still the dominant reading.

Where Rule 20 meets mass litigation

Rule 20 is under pressure in three kinds of modern cases.

BitTorrent "swarm" cases. In the 2010s, copyright plaintiffs (many of them adult-film companies) sued hundreds or thousands of "Doe" defendants identified only by IP address, alleging that each had downloaded the same file through the same BitTorrent swarm. The joinder theory was that every participant in a swarm shares pieces with every other participant. The D.C. Circuit rejected it for defendants who used the swarm at different times. AF Holdings, LLC v. Does 1-1058, 752 F.3d 990 (D.C. Cir. 2014). Two people who download the same file months apart, the court reasoned, are no more part of the same transaction than two people who bought the same book at different stores. The court also held that the plaintiff could not get early discovery on Does who almost certainly were not subject to personal jurisdiction in the District of Columbia. District courts elsewhere divided before AF Holdings, and many began severing all but one Doe as a matter of routine.

Patent cases. Before 2011, patent plaintiffs commonly sued dozens of unrelated companies in one complaint on the theory that each infringed the same patent. The Federal Circuit tightened the test in In re EMC Corp., 677 F.3d 1351 (Fed. Cir. 2012), holding that independent defendants making similar products are not properly joined unless the claims share an "aggregate of operative facts," but Congress had already acted. The America Invents Act added 35 U.S.C. § 299, which allows accused infringers to be joined as defendants (or their actions consolidated for trial) only if the claims arise from the same transaction or occurrence "relating to the making, using, importing into the United States, offering for sale, or selling of the same accused product or process" and share common questions of fact. Section 299(b) adds a pointed sentence: accused infringers "may not be joined in one action as defendants or counterclaim defendants, or have their actions consolidated for trial, based solely on allegations that they each have infringed the patent or patents in suit." The statute does not apply to Hatch-Waxman cases under § 271(e)(2), and an accused infringer can waive it.

Schedule A cases. Brand owners in the Northern District of Illinois and a handful of other courts file trademark, copyright, and design-patent suits against dozens or hundreds of online storefronts listed on a sealed "Schedule A," seek ex parte asset freezes, and usually win default judgments. Joinder is the model's pressure point. Some judges have accepted allegations of a coordinated network of sellers; others have required evidence that the defendants are actually connected, severed defendants who sell different products, or demanded separate filing fees. The Seventh Circuit has upheld personal jurisdiction over a storefront that shipped an infringing product into Illinois, NBA Properties, Inc. v. HANWJH, 46 F.4th 614 (7th Cir. 2022), but that decision did not address joinder, and the district-court rulings on joinder are individual and evolving. Practitioners on both sides should check the assigned judge's standing orders before filing or responding. The broader enforcement model is described in Counterfeiting, Seizure Orders, and Schedule A Litigation: Fighting Fakes in Federal Court.

Rule 21 and Rule 20(b)

Fed. R. Civ. P. 21 says misjoinder "is not a ground for dismissing an action." The court may "at any time, on just terms, add or drop a party" and may "sever any claim against a party." Severance creates separate actions, each with its own judgment, which matters for appeal and for venue: a severed claim can be transferred under 28 U.S.C. § 1404 on its own. Rule 20(b) and Fed. R. Civ. P. 42(b) are the gentler tools, ordering separate trials while keeping one action. Courts use dismissal without prejudice of misjoined parties as the Rule 21 remedy, which is generally harmless unless a limitations period has run in the meantime. That limitations risk is the reason defense counsel in mass-joinder cases should think carefully before moving to sever; occasionally, plaintiffs' counsel welcome severance because the clock is no problem and the separate filing fees are affordable.

Rule 21 also has a jurisdictional use. A court (including a court of appeals) may drop a dispensable nondiverse party to preserve diversity jurisdiction rather than dismiss the whole case. Newman-Green, Inc. v. Alfonzo-Larrain, 490 U.S. 826 (1989).

Required joinder: Rule 19

The three-step analysis

Fed. R. Civ. P. 19 asks three questions in order.

Is the absent person required? Under Rule 19(a)(1), a person is required if (A) the court cannot accord complete relief among the existing parties without it, or (B) the person claims an interest relating to the subject of the action and disposing of the action without it may (i) as a practical matter impair its ability to protect that interest or (ii) leave an existing party subject to a substantial risk of double, multiple, or inconsistent obligations.
Is joinder feasible? A required person must be joined if it is subject to service of process and its joinder will not destroy subject-matter jurisdiction. If it objects to venue and joinder would make venue improper, it must be dismissed.
If joinder is not feasible, should the case proceed? Rule 19(b) lists four factors: the prejudice a judgment would cause the absent person or the existing parties; whether protective provisions, shaped relief, or other measures could reduce that prejudice; whether a judgment without the person would be adequate; and whether the plaintiff would have an adequate remedy if the action were dismissed.

The defense is raised by motion under Fed. R. Civ. P. 12(b)(7) and, unusually, survives late: Rule 12(h)(2) preserves failure to join a required party through trial. Rule 19(c) requires a pleader to name any required person who is not joined and say why.

Provident Tradesmens: the case that made Rule 19 pragmatic

The modern reading of Rule 19 comes from Provident Tradesmens Bank & Trust Co. v. Patterson, 390 U.S. 102 (1968), decided two years after the 1966 amendments. A car owner named Dutcher lent his car to a friend; the friend let a third man drive; the car collided with a truck, killing two people and injuring the truck driver. The victims' estates and the truck driver sued Dutcher's insurer in federal court for a declaration that the driver had permission to use the car, which would bring him within the policy. Dutcher himself was not joined, because adding him would have destroyed diversity. The plaintiffs won at trial. On appeal, the Third Circuit raised the absence of Dutcher on its own and threw out the judgment, reasoning that Dutcher had a "substantive right" not to be affected by a judgment in his absence.

The Supreme Court reversed. Rule 19(b), the Court held, calls for a practical, case-specific weighing, not an inquiry into abstract substantive rights. The timing mattered: after a full trial, the plaintiffs' interest in keeping a judgment they had already won weighed heavily, and the risk to Dutcher could be managed because the judgment would not bind him. The appellate court, the Supreme Court said, should have asked whether the absent person was actually harmed, not whether he could theoretically be.

Temple v. Synthes: joint tortfeasors are not required

A patient whose spinal implant failed sued the manufacturer in federal court and, separately, sued his doctor and hospital in state court. The federal district court ordered him to join the doctor and hospital and dismissed when he did not. In a short per curiam opinion, the Supreme Court reversed: "It has long been the rule that it is not necessary for all joint tortfeasors to be named as defendants in a single lawsuit." Temple v. Synthes Corp., 498 U.S. 5 (1990). The Advisory Committee note to Rule 19 says the same. Temple is the first case a plaintiff cites when a defendant files a Rule 19 motion seeking to add a co-defendant the plaintiff chose not to sue, and it is why Rule 14, not Rule 19, is the tool a defendant uses when it wants someone else in the case.

Pimentel: sovereign immunity and the absent party

Republic of Philippines v. Pimentel, 553 U.S. 851 (2008) is the Court's most important modern Rule 19 decision, and it began as interpleader. Assets that Ferdinand Marcos allegedly stole had been transferred to a Panamanian company, Arelma, which held them in a Merrill Lynch brokerage account in New York. Several groups claimed the money: the Republic of the Philippines and its asset-recovery commission, which were litigating ownership in a Philippine anticorruption court; a class of roughly 9,500 human-rights victims holding a judgment against the Marcos estate; and others. Merrill Lynch filed statutory interpleader. The Republic and the commission were dismissed on sovereign immunity grounds, and then argued that the case could not go forward without them. The lower courts awarded the assets to the human-rights victims anyway.

The Supreme Court reversed and ordered dismissal. Where a required party's sovereign immunity claim is not frivolous and the litigation may injure the sovereign's interests, the Court held, dismissal "must be ordered." The Ninth Circuit had given too little weight to the Republic's immunity, to the comity owed to the pending Philippine proceedings, and to the fact that the Republic's claim was not frivolous merely because it might lose on the merits. Pimentel is cited constantly in cases involving foreign states and Indian tribes, which often cannot be joined because of immunity and whose interests the existing parties cannot protect. See Diné Citizens Against Ruining Our Environment v. Bureau of Indian Affairs, 932 F.3d 843 (9th Cir. 2019), where a tribe-owned mining company's immunity required dismissal of an environmental challenge to federal approvals for a mine and power plant.

Where Rule 19 arises in commercial practice

Contracts. A party to a contract is ordinarily required in an action to rescind or reform it, and often in an action to interpret it, because the judgment may affect its rights. Joint obligors, by contrast, are usually not required in an action for damages. Janney Montgomery Scott, Inc. v. Shepard Niles, Inc., 11 F.3d 399 (3d Cir. 1993).
Patents. All co-owners of a patent must ordinarily join as plaintiffs, and the Federal Circuit has held that Rule 19 cannot be used to force an unwilling co-owner into the case. STC.UNM v. Intel Corp., 754 F.3d 940 (Fed. Cir. 2014). But where a plaintiff lacks all substantial rights because a patent owner holds some of them, the court should consider joining that owner rather than dismissing. Lone Star Silicon Innovations LLC v. Nanya Technology Corp., 925 F.3d 1225 (Fed. Cir. 2019). The chain-of-title problems behind these cases are explained in Patent Ownership, Assignments, and Standing: Chain-of-Title Problems That Sink Cases.
Insurance and subrogation. An insurer that has paid part of a loss is a partial subrogee and a real party in interest along with its insured. United States v. Aetna Casualty & Surety Co., 338 U.S. 366 (1949). Courts usually treat the partially subrogated insurer as a party who should be joined if feasible, under Fed. R. Civ. P. 17(a) and Rule 19, so that the defendant is not sued twice for one loss.
Antitrust and distribution. A business partner whose contract is said to be part of the restraint is not automatically required. In Ward v. Apple Inc., 791 F.3d 1041 (9th Cir. 2015), the Ninth Circuit held that a carrier with an exclusive iPhone arrangement was not a required party to consumers' antitrust claims against Apple.

Impleader: Rule 14 third-party practice

Derivative liability, and nothing else

Fed. R. Civ. P. 14(a)(1) lets a defending party, "as third-party plaintiff, serve a summons and complaint on a nonparty who is or may be liable to it for all or part of the claim against it." The key words are "to it." Impleader is for indemnity, contribution, subrogation, breach of warranty running to the defendant, and similar claims whose existence depends on the defendant being held liable. It is not for the defense that "the third party, not me, is liable to the plaintiff." A defendant who believes someone else is solely responsible should deny liability and develop the empty-chair defense; it may not use Rule 14 to substitute a new defendant. Courts describe the requirement as one of derivative or secondary liability. See United States v. Joe Grasso & Son, Inc., 380 F.2d 749 (5th Cir. 1967); Stewart v. American International Oil & Gas Co., 845 F.2d 196 (9th Cir. 1988).

Whether the defendant has a substantive right to indemnity or contribution is a question of the governing substantive law, not of Rule 14. In a state that has abolished contribution among joint tortfeasors, or that allocates fault through comparative-fault verdict forms instead, a contribution third-party complaint may fail on the merits. In a state with a nonparty-at-fault statute, the defendant may be able to get a jury allocation against the absent party without impleading it at all. Check state law first.

Timing and leave

A defendant may file a third-party complaint without leave within 14 days after serving its original answer. After that, it needs leave of court, and courts consider prejudice to the plaintiff, the complexity added, whether the third-party claim is meritorious on its face, and whether the defendant delayed without excuse. A scheduling order under Fed. R. Civ. P. 16(b) usually sets a deadline for joining parties, and after that deadline the defendant must also show good cause to modify the schedule. The interaction between leave standards and scheduling orders is the same trap discussed for amendments in Amending Pleadings Under Rule 15: Leave to Amend, Relation Back, and the Scheduling Order Trap.

The third-party defendant's toolkit

Rule 14(a)(2) gives the third-party defendant a full set of tools. It must assert its Rule 12 defenses against the third-party plaintiff and any compulsory counterclaims; it may crossclaim against other third-party defendants; and, critically, it may assert against the original plaintiff "any defense that the third-party plaintiff has to the plaintiff's claim." That last right exists because the third-party defendant ends up paying if the plaintiff wins, and it cannot trust the defendant to fight hard (especially if the defendant has insurance and the third-party defendant does not). The third-party defendant may also assert claims against the plaintiff arising from the same transaction. Rule 14(a)(3) runs the other way: the plaintiff may assert claims directly against the third-party defendant. Rule 14(a)(4) lets any party move to strike, sever, or try the third-party claim separately, and Rule 14(a)(5) allows fourth-party complaints. Rule 14(b) lets a plaintiff implead when a counterclaim is asserted against it.

Admiralty is different. Under Rule 14(c), in a case designated as an admiralty or maritime claim under Rule 9(h), the defendant may implead someone who may be liable either to the defendant or to the plaintiff, and may demand judgment in the plaintiff's favor against the third-party defendant, which then defends against the plaintiff as if sued directly. For the admiralty context generally, see Maritime and Admiralty Law: Jurisdiction, Seamen, Cargo, and Vessel Liability.

Owen Equipment and the plaintiff's claim against the third-party defendant

Return to Mrs. Kroger. Her claim against the power company was within diversity jurisdiction. The power company's third-party claim against the crane operator was within ancillary jurisdiction, because it was derivative of the main claim and the power company was haled into court involuntarily. But her own amended claim against the operator was different. She was a plaintiff who had chosen the federal forum, and allowing her to sue a nondiverse defendant by waiting for the original defendant to implead it would let plaintiffs evade the complete-diversity requirement of Strawbridge v. Curtiss, 7 U.S. 267 (1806) through a two-step maneuver. Owen Equipment & Erection Co. v. Kroger, 437 U.S. 365 (1978). The Court held there was no jurisdiction, and the verdict she had won against the crane owner fell with it.

Section 1367(b) codifies the result. In a case founded solely on diversity, the court lacks supplemental jurisdiction over "claims by plaintiffs against persons made parties under Rule 14, 19, 20, or 24" when exercising jurisdiction would be inconsistent with § 1332. The defendant's third-party claim survives; the plaintiff's Rule 14(a)(3) claim against a nondiverse third-party defendant does not. In federal question cases, § 1367(b) does not apply, and the plaintiff's claim against the third-party defendant is ordinarily within supplemental jurisdiction under § 1367(a) if it arises from the same nucleus of facts.

Removal and the third-party defendant

A third-party defendant generally cannot remove a case. In Home Depot U.S.A., Inc. v. Jackson, 587 U.S. 435 (2019), a bank sued a consumer in North Carolina state court on a credit-card debt; the consumer filed class-action third-party claims against Home Depot and a water-treatment company. Home Depot removed under the general removal statute and the Class Action Fairness Act. The Court held, 5-4, that a third-party counterclaim defendant is not a "defendant" entitled to remove under 28 U.S.C. § 1441(a) or 28 U.S.C. § 1453(b). For the mechanics of removal and remand generally, see Removal and Remand: Getting a Case to Federal Court and Keeping It There.

Interpleader: Rule 22 and the federal interpleader statute

What interpleader is for

Interpleader lets a stakeholder holding money or property that several people claim deposit it with the court, drop out, and let the claimants fight. The stakeholder may be disinterested (an insurer that admits it owes a life-insurance benefit but does not know to whom) or interested (an insurer that disputes whether it owes anything, and also faces competing claims). The point is to avoid double liability and inconsistent judgments, and to end the stakeholder's role early.

The federal interpleader statute exists because of New York Life Insurance Co. v. Dunlevy, 241 U.S. 518 (1916), which held that a state court interpleader judgment did not bind a claimant over whom the court lacked personal jurisdiction. Insurers faced claimants in different states with no single court able to bind them all. Congress responded in 1917, and the modern statute is the result.

The two forms compared

Feature	Rule 22 interpleader	Statutory interpleader
Source	Fed. R. Civ. P. 22	28 U.S.C. § 1335, § 1397, § 2361
Subject-matter jurisdiction	Ordinary: federal question, or complete diversity between stakeholder and every claimant plus more than $75,000	Two or more adverse claimants of diverse citizenship; $500 or more
Deposit	Not required by the rule (often ordered)	Required: deposit the money or property, or post a bond
Venue	Ordinary venue under 28 U.S.C. § 1391	Any district where one or more claimants reside
Service	Ordinary Rule 4 limits	Nationwide
Injunction against other suits	Limited by the Anti-Injunction Act	Express authority to restrain other proceedings affecting the stake

The minimal-diversity point comes from State Farm Fire & Casualty Co. v. Tashire, 386 U.S. 523 (1967). A Greyhound bus and a pickup truck collided in northern California; two passengers died and dozens were injured. The pickup driver's insurer, State Farm, had a $20,000 per-occurrence limit. It filed statutory interpleader in Oregon, deposited the $20,000, and obtained an injunction requiring every claim arising from the crash, including the claims against Greyhound, to be brought in the interpleader proceeding. The Supreme Court made three holdings. First, Article III requires only minimal diversity; complete diversity under Strawbridge is a statutory rule, so Congress could authorize interpleader with just two diverse claimants. Second, an insurer need not wait until claims are reduced to judgment before interpleading. Third, the injunction went too far. Interpleader protects the stakeholder's fund; it is not a device to force all tort litigation arising from an accident into one forum. The insurer's $20,000 could not be "the tail which wags the dog."

How interpleader proceeds

Interpleader usually runs in two stages. In the first, the court decides whether interpleader is proper: is there a single fund, are there adverse claims, does the stakeholder face a real risk of multiple liability? If so, the court may accept the deposit, enjoin other proceedings against the stakeholder concerning the fund, and discharge the stakeholder. In the second stage, the claimants litigate entitlement among themselves. A disinterested stakeholder often recovers attorney's fees from the fund, though courts are less generous with insurers, for whom interpleader is a routine cost of business, and they will not discharge a stakeholder from independent claims (bad faith, for example) that do not depend on who owns the fund. See Prudential Insurance Co. of America v. Hovis, 553 F.3d 258 (3d Cir. 2009); Lee v. West Coast Life Insurance Co., 688 F.3d 1004 (9th Cir. 2012).

Interpleader also appears outside insurance: escrow agents facing conflicting instructions, banks holding disputed accounts, retirement plan administrators facing competing beneficiaries, and purchasers of a business holding back a payment that two sellers claim. For the escrow version, see Escrow Toolkit: Escrow Agreements, Joint Instructions, and Claim Notices.

Intervention: Rule 24

Intervention of right

Fed. R. Civ. P. 24(a) gives a right to intervene to anyone who files a timely motion and either (1) is given an unconditional right to intervene by federal statute, or (2) "claims an interest relating to the property or transaction that is the subject of the action, and is so situated that disposing of the action may as a practical matter impair or impede the movant's ability to protect its interest, unless existing parties adequately represent that interest."

Statutory rights under Rule 24(a)(1) are few but important: the United States (and a state) may intervene when the constitutionality of a federal (or state) statute is drawn into question in a case to which it is not a party, 28 U.S.C. § 2403, with notice procedures in Fed. R. Civ. P. 5.1; the EEOC and aggrieved persons have intervention rights in Title VII actions, 42 U.S.C. § 2000e-5(f)(1); and in qui tam cases, the government may intervene within the seal period or later for good cause, 31 U.S.C. § 3730(b)-(c). The last is discussed in False Claims Act Qui Tam Litigation: The Seal, Materiality, Scienter, and Government Intervention.

Under Rule 24(a)(2), courts break the test into four elements: timeliness, interest, impairment, and inadequate representation.

Interest. The interest must be "significantly protectable," a phrase from Donaldson v. United States, 400 U.S. 517 (1971). Property rights and contract rights at stake in the case qualify. A purely economic interest in the outcome (a creditor of a party, a competitor who would benefit if one side lost) usually does not. Courts are divided on whether the precedential effect of a ruling can be enough; the Fifth Circuit has said stare decisis can supply the practical impairment in some cases, and other circuits treat it as relevant only in unusual situations.

Impairment. The question is practical, not legal: will the case's disposition, as a practical matter, make it harder for the movant to protect its interest? Formal preclusion is not required. The leading early case is Cascade Natural Gas Corp. v. El Paso Natural Gas Co., 386 U.S. 129 (1967), in which the Court held that California and two other interested parties were entitled to intervene in shaping an antitrust divestiture decree that would determine the structure of the new gas company serving them.

Inadequate representation. Trbovich v. United Mine Workers, 404 U.S. 528 (1972) set the standard. A union member had complained to the Secretary of Labor about a union election; the Secretary sued to set the election aside, and the member asked to intervene. The Court allowed it, limited to the grounds the Secretary had raised, because the Secretary had a dual duty (to the individual member and to the public interest in fair union elections) that might pull in different directions. The requirement is satisfied if the applicant shows that representation of its interest "may be" inadequate, and "the burden of making that showing should be treated as minimal."

Courts of appeals then built presumptions on top of Trbovich: a presumption of adequacy when the applicant and a party share the same "ultimate objective," and a stronger presumption when the party is a government entity charged with representing the applicant's interest. Arakaki v. Cayetano, 324 F.3d 1078 (9th Cir. 2003). Berger v. North Carolina State Conference of the NAACP, 597 U.S. 179 (2022) put those presumptions under strain. North Carolina's legislative leaders sought to intervene to defend the state's voter-identification law alongside the State Board of Elections, which was represented by an attorney general who, as a legislator, had opposed an earlier voter-identification law. A state statute expressly authorized the leaders to defend state laws on the State's behalf. The lower courts presumed the Board adequate. The Supreme Court reversed, 8-1. It held that a presumption of adequate representation is inappropriate when a duly authorized state agent seeks to intervene to defend a state law, reaffirmed that the Trbovich burden is minimal, and pointedly declined to endorse a presumption of adequacy in other government-representation settings. Lower courts have since split on how much of the "same ultimate objective" presumption survives.

Timeliness

Timeliness is judged from all the circumstances and reviewed for abuse of discretion. NAACP v. New York, 413 U.S. 345 (1973). Courts usually ask how long the movant knew or should have known its interest was at stake, the prejudice to existing parties from the delay, the prejudice to the movant if denied, and any unusual circumstances. Stallworth v. Monsanto Co., 558 F.2d 257 (5th Cir. 1977). The clock runs from when the movant knew its interest was not being protected, not from when the case was filed. That principle carried the day in United Airlines, Inc. v. McDonald, 432 U.S. 385 (1977), where a putative class member moved to intervene promptly after final judgment, once the named plaintiffs made clear they would not appeal the denial of class certification, and the motion was timely.

Cameron v. EMW Women's Surgical Center, P.S.C., 595 U.S. 267 (2022) applied the same logic on appeal. Kentucky's health secretary had defended a state abortion restriction through an adverse Sixth Circuit decision, and then, after a change in administration, decided not to seek further review. The state attorney general moved to intervene in the court of appeals within two days. The Sixth Circuit called the motion untimely because the case was years old. The Supreme Court reversed, 8-1: the Federal Rules of Appellate Procedure have no general intervention rule, but the policies of Rule 24 apply, and the attorney general moved as soon as it became clear the secretary would stop defending the law. The state's interest in defending its own statutes weighed heavily.

Standing and the intervenor

In Town of Chester v. Laroe Estates, Inc., 581 U.S. 433 (2017), a developer sued a town for a regulatory taking, and a company that had paid the developer for the land sought to intervene of right as a co-plaintiff seeking its own damages. The Court held unanimously that "an intervenor of right must have Article III standing in order to pursue relief that is different from that which is sought by a party with standing," including a money judgment in the intervenor's own name. An intervenor that merely supports the relief an existing party seeks does not need independent standing to participate, though some circuits, notably the D.C. Circuit, have long required intervenors to show standing. Fund for Animals, Inc. v. Norton, 322 F.3d 728 (D.C. Cir. 2003). An intervenor who wants to appeal alone after the original party gives up must have standing of its own. Diamond v. Charles, 476 U.S. 54 (1986); Hollingsworth v. Perry, 570 U.S. 693 (2013); Virginia House of Delegates v. Bethune-Hill, 587 U.S. 658 (2019).

Permissive intervention

Rule 24(b)(1)(B) allows the court to permit intervention by anyone who "has a claim or defense that shares with the main action a common question of law or fact." Rule 24(b)(2) allows government officers and agencies to intervene when a party's claim or defense is based on a statute or regulation they administer. Under Rule 24(b)(3), the court "must consider whether the intervention will unduly delay or prejudice the adjudication of the original parties' rights." Permissive intervention is discretionary and rarely reversed. Many courts add a requirement of an independent jurisdictional basis for the intervenor's claims, but relax it when the intervenor seeks only to modify a protective order or unseal records rather than to litigate the merits. EEOC v. National Children's Center, Inc., 146 F.3d 1042 (D.C. Cir. 1998); Beckman Industries, Inc. v. International Insurance Co., 966 F.2d 470 (9th Cir. 1992).

That relaxation is the doorway for the press and for collateral litigants seeking access to sealed filings and discovery. See Pansy v. Borough of Stroudsburg, 23 F.3d 772 (3d Cir. 1994), where newspapers intervened to seek access to a settlement agreement, and Foltz v. State Farm Mutual Automobile Insurance Co., 331 F.3d 1122 (9th Cir. 2003), where collateral litigants intervened to modify a protective order. The access standards themselves are covered in Protective Orders, Confidentiality Designations, and Sealing: Secrecy and Its Limits in Federal Court.

Appeal

A nonparty who wants to appeal an adverse judgment generally must first intervene. Marino v. Ortiz, 484 U.S. 301 (1988). Unnamed class members who object to a settlement are an exception. Devlin v. Scardelletti, 536 U.S. 1 (2002). An order denying intervention of right is generally treated as a final, appealable order as to the would-be intervenor, while an order granting intervention, or granting permissive intervention with conditions, is not immediately appealable. Stringfellow v. Concerned Neighbors in Action, 480 U.S. 370 (1987).

Substitution and representative parties: Rules 25, 23.1, and 23.2

Fed. R. Civ. P. 25 handles changes in party identity after filing. If a party dies and the claim survives, a motion to substitute must be made within 90 days after service of a statement noting the death, or the action against (or by) the decedent must be dismissed. Rule 25(c) lets an action continue by or against the original party after a transfer of interest, unless the court orders the transferee substituted or joined. Public officers sued in an official capacity are substituted automatically under Rule 25(d). Substitution does not defeat diversity jurisdiction once established; in Freeport-McMoRan, Inc. v. K N Energy, Inc., 498 U.S. 426 (1991), the Court held that a nondiverse transferee substituted under Rule 25(c) did not oust the court of jurisdiction.

Two representative rules sit alongside. Fed. R. Civ. P. 23.1 governs shareholder derivative suits, in which the shareholder sues on the corporation's behalf and the corporation is joined as a nominal defendant; the details are in Shareholder Derivative Litigation: Demand Futility, Special Litigation Committees, and Settlement. Fed. R. Civ. P. 23.2 lets members of an unincorporated association sue or be sued as representatives of the association. Class actions under Rule 23 are the largest representative device of all; see Class Actions Under Rule 23: Certification, Settlement, and Defense Strategy.

The jurisdictional overlay

Every party-joinder rule carries the warning of Fed. R. Civ. P. 82: the rules "do not extend or limit the jurisdiction of the district courts or the venue of actions in those courts." Permission to join under Rule 20 says nothing about whether the court can hear the claim against the new party. Five jurisdictional problems recur.

1. Complete diversity and the time-of-filing rule

In a diversity case under 28 U.S.C. § 1332, no plaintiff may share citizenship with any defendant. Adding a nondiverse defendant destroys jurisdiction over the whole action, not just the new claim. Jurisdiction is measured at filing, and a later change in a party's citizenship does not cure an original defect. Grupo Dataflux v. Atlas Global Group, L.P., 541 U.S. 567 (2004). Dropping the spoiler under Rule 21 does cure it, which is why Newman-Green matters. And if a case was improperly removed but the nondiverse party is dismissed before judgment, the judgment stands. Caterpillar Inc. v. Lewis, 519 U.S. 61 (1996).

Citizenship errors are common with business entities. A corporation is a citizen of its state of incorporation and the state of its principal place of business, its "nerve center." Hertz Corp. v. Friend, 559 U.S. 77 (2010). An LLC, partnership, or other unincorporated entity takes the citizenship of every member, traced through every layer. Americold Realty Trust v. ConAgra Foods, Inc., 577 U.S. 378 (2016). A new party that is an LLC needs a full membership trace before anyone signs a pleading adding it.

Manufactured diversity is barred. Under 28 U.S.C. § 1359, a court lacks jurisdiction where a party "by assignment or otherwise, has been improperly or collusively made or joined to invoke" it. In Kramer v. Caribbean Mills, Inc., 394 U.S. 823 (1969), an assignment of a claim to an out-of-state attorney for $1, with a side agreement to pay most of the recovery back, was collusive.

2. Supplemental jurisdiction and § 1367(b)

28 U.S.C. § 1367(a) grants supplemental jurisdiction over claims forming part of the same Article III case, "including claims that involve the joinder or intervention of additional parties." Subsection (b) then subtracts, in diversity-only cases, claims by plaintiffs against persons made parties under Rules 14, 19, 20, or 24, and claims by persons proposed to be joined as plaintiffs under Rule 19 or seeking to intervene as plaintiffs under Rule 24, when exercising jurisdiction would be inconsistent with § 1332.

Read literally, § 1367(b) leaves some odd gaps. It restricts claims "by plaintiffs," so it does not restrict a defendant's third-party claim, crossclaim, or Rule 13(h) counterclaim joinder. And it does not list persons joined as plaintiffs under Rule 20. In Exxon Mobil Corp. v. Allapattah Services, Inc., 545 U.S. 546 (2005), the Court took the text at its word. In two consolidated cases (a class action by Exxon dealers and a suit by a young girl who cut her hand on a tuna can, joined by family members with smaller claims), the Court held that § 1367 permits supplemental jurisdiction over the claims of co-plaintiffs, whether joined under Rule 20 or as class members under Rule 23, who do not individually satisfy the amount in controversy, as long as at least one plaintiff does and complete diversity exists. The Court rejected the argument that a single small claim "contaminates" the whole action, while reaffirming that a nondiverse party does contaminate it: complete diversity remains required. The practical result for plaintiffs: co-plaintiffs with small claims can ride along with one plaintiff who exceeds $75,000, but a nondiverse co-plaintiff or intervening plaintiff cannot.

3. Joinder after removal: § 1447(e) and fraudulent joinder

After removal on diversity, plaintiffs sometimes try to add a nondiverse defendant (often a local store manager, employee, or distributor) to force remand. 28 U.S.C. § 1447(e) gives the court two choices: deny joinder, or permit joinder and remand. Courts weigh the factors from Hensgens v. Deere & Co., 833 F.2d 1179 (5th Cir. 1987): whether the purpose is to defeat jurisdiction, whether the plaintiff was dilatory, whether the plaintiff will be significantly harmed if joinder is denied, and other equities. The Fourth Circuit treats the fraudulent-joinder doctrine as one factor in the § 1447(e) analysis. Mayes v. Rapoport, 198 F.3d 457 (4th Cir. 1999). Plaintiffs should also remember Royal Canin U.S.A., Inc. v. Wullschleger, 604 U.S. 22 (2025): when a plaintiff amends after removal to delete the federal claims that supported removal, the federal court loses supplemental jurisdiction over the state claims and must remand. Amendments that change parties or claims change the jurisdictional analysis.

Fraudulent (or "improper") joinder is the defendant's counterpart. A removing defendant may ignore the citizenship of a nondiverse defendant if there is no reasonable possibility that the plaintiff can recover against it under state law, or if jurisdictional facts were pleaded fraudulently. Smallwood v. Illinois Central Railroad Co., 385 F.3d 568 (5th Cir. 2004) (en banc). The standard is more demanding than Rule 12(b)(6) in some circuits; the Ninth Circuit has emphasized that a defendant must show the plaintiff could not possibly state a claim, even with leave to amend. Grancare, LLC v. Thrower, 889 F.3d 543 (9th Cir. 2018). A distinct and more contested doctrine, "fraudulent misjoinder," addresses a nondiverse plaintiff or defendant whose claims are properly pleaded but have no real connection to the diverse claims. The Eleventh Circuit recognized it in Tapscott v. MS Dealer Service Corp., 77 F.3d 1353 (11th Cir. 1996) for "egregious" misjoinder. Many district courts have declined to follow it, and the circuits have not settled the question. The broader removal picture, including the one-year limit for diversity removal in 28 U.S.C. § 1446(c), is in Removal and Remand: Getting a Case to Federal Court and Keeping It There.

4. Personal jurisdiction, service, and venue over added parties

Every new defendant needs a basis for personal jurisdiction and an authorized method of service. Omni Capital International, Ltd. v. Rudolf Wolff & Co., 484 U.S. 97 (1987). Usually that means the forum state's long-arm reach under Fed. R. Civ. P. 4(k)(1)(A), measured by the due process tests of cases like Ford Motor Co. v. Montana Eighth Judicial District Court, 592 U.S. 351 (2021). Rule 4(k)(1)(B) adds a narrow extension: parties joined under Rule 14 or Rule 19 may be served "within a judicial district of the United States and not more than 100 miles from where the summons was issued." Courts generally read this "bulge" as requiring contacts with the 100-mile area, not with the forum state. It does not help Rule 20 defendants or intervenors (who come voluntarily and submit to jurisdiction). Statutory interpleader and other federal statutes with nationwide service (Rule 4(k)(1)(C)) go further.

Joinder of plaintiffs has a personal jurisdiction dimension too. In Bristol-Myers Squibb Co. v. Superior Court, 582 U.S. 255 (2017), hundreds of plaintiffs, most of them not California residents, joined a mass action in California state court against a drug maker not at home there. The Court held that the nonresidents' claims, which had no connection to California, could not be heard there on a specific-jurisdiction theory, even though the residents' identical claims could. Each plaintiff's claim must connect to the forum. For the doctrine generally, see Personal Jurisdiction Over Online and Foreign Defendants: From Zippo to Ford Motor.

Venue is evaluated for the original claim. Third-party claims, compulsory counterclaims, and intervention generally do not need independent venue, but Rule 19(a)(3) lets a required party who objects to venue be dismissed if its joinder would make venue improper. Severed claims become separate actions and must satisfy venue on their own. See Venue and Transfer Checklist: A Practical Checklist.

5. Limitations and relation back for new parties

A claim against a party added after limitations runs survives only if it relates back under Fed. R. Civ. P. 15(c)(1)(C): the new claim must arise from the same conduct, and within the Rule 4(m) service period the new party must have received notice of the action and known or should have known that it would have been sued but for a mistake about the proper party's identity. The focus is on what the new party knew, not on whether the plaintiff's mistake was careless. Krupski v. Costa Crociere S.p.A., 560 U.S. 538 (2010). Many circuits hold that naming a "John Doe" because the plaintiff did not know the defendant's identity is not a "mistake." Relation back is covered in depth in Amended Pleading and Relation Back Checklist: A Practical Checklist and Moving for or Opposing Leave to Amend a Pleading: A Practical Guide.

Splits and open questions

How much of the "same objective" presumption survives Berger? Berger rejected a presumption of adequacy for a state agent authorized by state law, and noted the Trbovich burden is minimal, but it did not abolish presumptions generally. Some circuits continue to apply a presumption of adequacy where the applicant and a party share the same ultimate objective; others now treat that presumption more skeptically. The question matters most for trade associations and industry groups seeking to defend agency rules alongside the government.
Do permissive intervenors need standing? Laroe Estates addressed intervenors of right seeking different relief. The D.C. Circuit has long required standing of intervenors generally; most circuits do not for intervenors who seek the same relief as a party. Whether Laroe's logic extends to permissive intervenors seeking distinct relief is not settled.
Is precedential effect a protectable interest? Most circuits say a stare decisis effect alone is not enough, but the Fifth Circuit has allowed it to supply practical impairment in some settings. Movants should not rely on it alone.
Fraudulent misjoinder. Recognized by the Eleventh Circuit, rejected or questioned by many district courts, and unresolved in most circuits.
Schedule A joinder. District judges in the Northern District of Illinois and elsewhere apply differing standards to mass-defendant counterfeiting complaints. Expect continued divergence until a court of appeals addresses Rule 20 squarely.
The 100-mile bulge. Courts disagree on whether contacts with the bulge area must be measured against the third-party claim or the party generally, and on how the bulge interacts with modern specific-jurisdiction doctrine.
Insurer intervention in liability suits. Courts usually deny an insurer's motion to intervene in a suit against its insured when the insurer is defending under a reservation of rights, reasoning that its interest is contingent on the coverage question. Travelers Indemnity Co. v. Dingwell, 884 F.2d 629 (1st Cir. 1989). A minority allow limited intervention to seek special interrogatories that will help resolve coverage. Practice varies within circuits.

What it means for each side

Plaintiffs. Decide party structure before filing, because a nondiverse defendant added later can destroy the forum. Plead joinder facts, not labels: the common policy, the shared supply chain, the single accident. In diversity cases, trace every party's citizenship, including LLC members. If a required party cannot be joined, plead the reason (Rule 19(c)) and be ready to argue the Rule 19(b) factors with Provident Tradesmens and Temple. When a defendant impleads a nondiverse party, do not assume you can assert a direct claim against it.

Defendants. Calendar the 14-day impleader window from the date the answer is served. Tender the defense to indemnitors and insurers before impleading; a cooperative indemnitor is cheaper than a third-party defendant. Use Rule 19 for genuine absent-party prejudice, not to add co-defendants. Test misjoinder early in mass-defendant cases, but think about whether severance helps or merely multiplies your costs. Watch for opportunities to remove when a nondiverse defendant is fraudulently joined, and for the one-year limit if the plaintiff later drops it.

Nonparties. Monitor cases that affect your property, contracts, regulatory approvals, or access rights. Move promptly when an existing party stops protecting your interest, because timeliness runs from that moment. Attach the proposed pleading required by Rule 24(c). If you want to appeal, you must be a party. If you seek relief of your own, establish your own standing. For an insurer or stakeholder facing competing claims, interplead early and deposit the fund.

Extended worked example: the warehouse fire

The facts. Calloway Distribution, LLC operates a refrigerated warehouse outside Columbus, Ohio. Its two members are Ohio citizens. In 2025 it hired SunRidge Installers, Inc. (incorporated in Delaware, headquartered in Pittsburgh) to install a rooftop solar array, using panels and inverters made by Kestrel Photovoltaic Corp. (incorporated in Delaware, headquartered in Dayton, Ohio). In February 2026, an inverter fault started a roof fire. Calloway's inventory was destroyed; a subtenant, Brightline Foods, Inc. (a Pennsylvania corporation based in Erie), lost its stock; and a firefighter was injured. Calloway's property insurer, Granite Mutual, paid $1.8 million of Calloway's roughly $3 million loss. SunRidge carries a $2 million general liability policy with Harborline Casualty.

Step 1: Calloway's complaint. Calloway sues SunRidge in the Southern District of Ohio for negligence and breach of contract, invoking diversity. It does not sue Kestrel, which would destroy diversity. That is a legitimate choice: Temple means SunRidge cannot force Kestrel in as a Rule 19 co-defendant merely because Kestrel is a joint tortfeasor.

Step 2: SunRidge's Rule 19 motion on Granite. SunRidge moves under Rule 12(b)(7) to require joinder of Granite, the partial subrogee, so that it does not face a second suit for the $1.8 million. Under Aetna, Granite owns part of the claim. Granite (an Indiana mutual company) is diverse from SunRidge, so joinder is feasible. The court orders joinder, and Granite joins as a co-plaintiff. Its claim is within § 1332 on its own, so § 1367(b) does not matter.

Step 3: SunRidge impleads Kestrel. Ten days after serving its answer, SunRidge files a third-party complaint against Kestrel for contribution and contractual indemnity under its distributor agreement. No leave is needed. Supplemental jurisdiction covers SunRidge's claim against Kestrel because § 1367(b) restricts only claims by plaintiffs. Kestrel answers, asserts Calloway's contributory negligence as a defense to Calloway's claim under Rule 14(a)(2)(C), and counterclaims against SunRidge for installation errors.

Step 4: Calloway tries to sue Kestrel directly. Calloway moves to amend to add a Rule 14(a)(3) claim against Kestrel. This is Owen Equipment: Calloway (Ohio) cannot assert a diversity-based claim against Kestrel (Ohio). Section 1367(b) bars it. Calloway's lawyers instead file a separate state-court action against Kestrel, protecting the limitations period, and the federal court considers whether to stay its third-party claim or proceed.

Step 5: Harborline interpleads. Harborline faces claims against SunRidge from Calloway and Granite (about $3 million combined), Brightline ($900,000), and the firefighter (unliquidated). Its $2 million limit is inadequate. It files statutory interpleader under § 1335 in the Western District of Pennsylvania, where Brightline resides, deposits $2 million, and seeks a § 2361 injunction. Minimal diversity is easy: Calloway (Ohio) and Brightline (Pennsylvania) are adverse claimants of diverse citizenship. Under Tashire, the court enjoins claimants from enforcing any judgment against Harborline's policy proceeds outside the interpleader, but refuses to enjoin the underlying liability suits against SunRidge or Kestrel. The fund is protected; the tort cases continue.

Step 6: Brightline seeks to intervene in the Ohio case. Brightline moves to intervene as a plaintiff against SunRidge under Rule 24(a)(2) and (b). It is a Pennsylvania citizen, and so is SunRidge. Section 1367(b) bars claims "by persons ... seeking to intervene as plaintiffs under Rule 24" when inconsistent with § 1332, and complete diversity would fail. The court denies intervention. Brightline sues SunRidge in Pennsylvania state court instead and participates in the interpleader.

Step 7: The firefighter. The firefighter, an Ohio citizen, sues SunRidge in Ohio state court and names a Columbus-based SunRidge site supervisor (also an Ohio citizen). SunRidge removes and argues fraudulent joinder of the supervisor. Like most states, Ohio generally allows an employee who personally participates in a tort to be held personally liable for it, and the complaint alleges that the supervisor overrode an inverter fault alarm. The court finds a reasonable possibility of recovery against the supervisor and remands under Smallwood-type reasoning.

What the example shows. The same fire generated a required-party joinder, a proper impleader, a barred plaintiff's claim, a successful interpleader, a denied intervention, and a remand. In each case the outcome turned less on the joinder rule than on jurisdiction and citizenship. A lawyer who maps every party's citizenship on day one would have predicted every result.

Common mistakes

Using Rule 14 to shift blame. A third-party complaint alleging that the nonparty is liable to the plaintiff, rather than to the defendant, will be struck.
Missing the 14-day window. After it closes, leave is needed, and after the scheduling-order deadline, good cause too.
Asserting a plaintiff's claim against a nondiverse third-party defendant. Owen Equipment and § 1367(b) bar it in diversity-only cases, and the error may not surface until after trial.
Ignoring LLC citizenship. A single member of a member of an LLC who shares citizenship with the other side destroys diversity.
Filing a Rule 19 motion to add a joint tortfeasor. Temple forecloses it, and the motion signals weakness.
Moving to intervene without a proposed pleading. Rule 24(c) requires one. Some courts excuse the omission; others deny the motion outright.
Waiting to intervene until the appeal. Timeliness runs from when the movant knew its interest was not being protected; after that point, delay is fatal.
Treating interpleader as a global-settlement device. Under Tashire, the court protects the fund, not the stakeholder's insured from liability litigation.
Severing without checking limitations. A severed and dismissed defendant may be time-barred when refiled.
Assuming Rule 4(k)(1)(B) covers everyone. The 100-mile bulge reaches only Rule 14 and Rule 19 parties.

Frequently asked questions

Can a defendant force the plaintiff to sue someone else? Not usually. A defendant can implead someone liable to it (Rule 14) or seek joinder of a genuinely required party (Rule 19), but it cannot make the plaintiff sue a joint tortfeasor. Temple v. Synthes settles that.

What is the difference between a crossclaim and a third-party claim? A crossclaim under Rule 13(g) runs against someone who is already a coparty. A third-party claim under Rule 14 brings in a nonparty. Both may seek indemnity or contribution.

Can a plaintiff sue a third-party defendant directly? Yes, under Rule 14(a)(3), if the claim arises out of the same transaction, but in a diversity-only case the claim needs its own complete diversity.

When should an insurer interplead rather than wait? When it faces multiple claims that together exceed its limits, or competing claims to a single benefit, and wants to avoid paying twice or being accused of favoring one claimant. Tashire allows interpleader before claims are reduced to judgment.

Does an intervenor have to show standing? If it seeks relief different from what an existing party with standing seeks, yes. Laroe Estates. If it seeks to appeal alone, yes. If it simply supports one side, most circuits do not require it, but the D.C. Circuit does.

Can the press intervene to unseal records? Yes. Courts regularly permit limited-purpose permissive intervention to challenge sealing or protective orders, often relaxing the independent-jurisdiction requirement. The guide Negotiating a Protective Order and Filing Under Seal: A Practical Guide explains the underlying standards.

What happens if a party dies during the case? A motion to substitute the proper party (usually the estate's representative) must be filed within 90 days after a statement noting the death is served under Rule 25(a), or the claims by or against the decedent are dismissed.

Takeaways

Ask four questions every time the party lineup changes: rule, subject-matter jurisdiction, personal jurisdiction and venue, and strategy.
Rule 19 is pragmatic. Courts weigh real prejudice, and joint tortfeasors are never required.
Rule 14 is derivative. If the nonparty would owe the plaintiff but not the defendant, it is not an impleader case.
Statutory interpleader is a powerful tool with minimal diversity and nationwide service, but it protects the fund, not the stakeholder's insured.
Intervention turns on timeliness and adequacy. Move when representation becomes inadequate, attach a pleading, and establish standing for any distinct relief.
In diversity cases, § 1367(b), complete diversity, and § 1447(e) are where joinder decisions are won and lost.

For the companion materials, see Party Joinder and Third-Party Practice Checklist: A Practical Checklist and Party Practice Toolkit: Third-Party Complaints, Intervention Motions, and Joinder Analyses.

This document is general information, not legal advice for any particular situation. Joinder, jurisdiction, and limitations rules turn on specific facts and on state law; consult counsel about your case.