I Doctrinal Framework

A joinder problem should proceed in sequence.

This sequence prevents the most common exam mistake: saying “the rule allows joinder” and forgetting jurisdiction.

II Claim Joinder by a Plaintiff

A plaintiff may generally join as many claims as the plaintiff has against an opposing party. The claims do not need to arise from the same transaction or occurrence.

For example, if Paula sues David, Paula may join a contract claim from a failed business deal, a tort claim from an unrelated car accident, and a property claim involving a boundary dispute. The claim-joinder rule (Rule 18) is extremely broad.

But procedural permission does not automatically create federal subject-matter jurisdiction. If Paula files in federal court, each claim must have an independent jurisdictional basis or fall within supplemental jurisdiction. If the contract claim is a federal claim and the unrelated tort claim is a state-law claim, supplemental jurisdiction may not cover the unrelated tort claim because it does not arise from the same case or controversy.

In diversity cases, the amount in controversy rules may allow a single plaintiff to aggregate multiple claims against a single defendant, even if unrelated. Thus, broad claim joinder sometimes works together with diversity aggregation.

III Permissive Joinder of Parties

Permissive party joinder (Rule 20) allows multiple plaintiffs or multiple defendants to join in one action when two requirements are met.

This standard is designed to permit related disputes to proceed together without allowing completely unrelated parties to be bundled into one case.

For example, several passengers injured in the same bus crash may sue the driver and bus company in one action. Their claims arise from the same occurrence, and common questions include negligence, causation, and damages evidence.

By contrast, ten unrelated plaintiffs who were injured by the same defendant in ten unrelated accidents over several years usually may not join merely because each alleges negligence. The claims do not arise from the same transaction or occurrence.

IV Counterclaims

A counterclaim is a claim asserted by an opposing party against a party who has already asserted a claim against it. Most commonly, the defendant asserts a counterclaim against the plaintiff.

Counterclaims are divided into compulsory and permissive counterclaims.

A. Compulsory Counterclaims

A compulsory counterclaim arises out of the same transaction or occurrence as the opposing party’s claim and generally must be asserted in the current action if it does not require adding a party over whom the court cannot acquire jurisdiction. Failure to assert a compulsory counterclaim may bar the party from bringing it later.

The same-transaction-or-occurrence standard is practical. Courts consider whether the claims involve many of the same facts, witnesses, documents, and legal issues, and whether resolving them together promotes efficiency.

Suppose Paula sues David for injuries from a car crash. David claims Paula caused the same crash and damaged David’s car. David’s claim arises from the same occurrence and is likely a compulsory counterclaim. If David fails to assert it, he may lose the ability to bring it later.

Compulsory counterclaims are often supported by supplemental jurisdiction because they arise from the same common nucleus of operative fact as the original claim. This is why they are frequently litigated in federal court even when they lack an independent federal-question or diversity basis.

B. Permissive Counterclaims

A permissive counterclaim does not arise out of the same transaction or occurrence. It may be asserted, but it need not be. Failure to assert it does not ordinarily bar later litigation.

Suppose Paula sues David for injuries from a car crash. David wants to sue Paula for failing to repay an unrelated loan. That loan claim is a permissive counterclaim. It does not arise from the same transaction or occurrence as the crash.

A permissive counterclaim generally needs its own basis for federal subject-matter jurisdiction. Supplemental jurisdiction usually will not cover it because it is not part of the same case or controversy.

V Crossclaims

A crossclaim is a claim by one party against a co-party. A defendant may assert a crossclaim against another defendant. A plaintiff may assert a crossclaim against another plaintiff.

A crossclaim must arise out of the same transaction or occurrence as the original action or a counterclaim, or relate to property that is the subject of the original action. Crossclaims are never compulsory under the Federal Rules. A party may assert a crossclaim, but failure to do so does not automatically bar a later action under the joinder rule itself.

For example, Paula sues Driver and Truck Company for a crash. Driver claims Truck Company’s defective brakes caused the crash. Driver may assert a crossclaim against Truck Company for indemnity or contribution if it arises from the same accident.

Because crossclaims arise from the same transaction or occurrence, supplemental jurisdiction often exists. But always analyze jurisdiction separately.

VI Impleader (Third-Party Practice)

Impleader allows a defending party to bring in a nonparty who may be liable to the defending party for all or part of the plaintiff’s claim. The defending party becomes a third-party plaintiff, and the new party becomes a third-party defendant.

The key requirement is derivative or secondary liability. The third-party defendant’s liability must depend on the defendant’s liability to the plaintiff. Common examples include indemnity, contribution, subrogation, and warranty obligations.

Impleader is not a device for blaming someone else directly to the plaintiff. A defendant may not implead a third party merely by saying, “That person, not me, injured the plaintiff.” The defendant must assert that if the defendant is liable to the plaintiff, the third party is liable over to the defendant.

Impleader Procedure and Jurisdiction

A defending party may implead a third-party defendant within the time allowed by the rule without leave of court; after that, leave is required. The third-party defendant must be served and brought under the court’s authority.

Once impleaded, the third-party defendant may assert defenses against the third-party plaintiff and may assert certain claims arising from the same transaction or occurrence. The plaintiff may also assert claims against the third-party defendant if the rules allow and jurisdiction exists.

Jurisdiction is essential. An impleader claim for indemnity or contribution will often fall within supplemental jurisdiction because it is related to the original claim. But plaintiff claims against third-party defendants in diversity-only cases may be restricted by supplemental-jurisdiction limits. This prevents plaintiffs from using impleader to evade diversity requirements.

VII Required Parties (Rule 19)

Some persons are so connected to the dispute that the court should attempt to join them if feasible. Required-party analysis protects absent persons, existing parties, and the integrity of judgments.

Dismissal is not automatic merely because a required person cannot be joined. The court balances practicality, fairness, and the need for resolution.

VIII Intervention

Intervention allows a nonparty to actively enter ongoing litigation. There are two main forms: intervention of right and permissive intervention.

• Intervention of Right: Required when the applicant has an interest relating to the property or transaction that is the subject of the action, disposition may impair or impede the applicant’s ability to protect that interest, and existing parties do not adequately represent the applicant’s interest. (e.g., litigation threatens a person's claimed ownership interest in specific property).
• Permissive Intervention: May be allowed when the applicant has a claim or defense sharing a common question of law or fact with the main action. The court considers whether intervention will unduly delay or prejudice the adjudication of the original parties’ rights.

Timeliness is required for both forms. A person who waits too long may be denied intervention even if the person otherwise has a strong interest.

IX. Interpleader

Interpleader protects a stakeholder from multiple liability when several claimants assert rights to the same property, fund, or obligation. The stakeholder asks the court to bring the claimants into one action so their competing claims can be resolved together.

For example, an insurance company may face competing claims to the same life-insurance proceeds. Rather than pay one claimant and risk suit by another, the insurer may file interpleader and deposit the funds with the court.

Interpleader may proceed under rule interpleader (Rule 22) or statutory interpleader (28 U.S.C. § 1335). The two forms differ in jurisdictional requirements, venue, service, and amount thresholds. For exam purposes, the central concept is that interpleader is appropriate when a stakeholder faces competing claims to the same stake and wants protection from inconsistent obligations or multiple liability.

X Class Actions (Rule 23)

A class action allows one or more representative parties to litigate on behalf of a larger group. Class actions can promote efficiency and access to justice when many persons have similar claims that would be impractical to litigate individually.

A. The Four Prerequisites (Rule 23a)

Class certification requires careful analysis. The party seeking certification must first satisfy four prerequisites.

B. Types of Class Actions and Jurisdiction

After satisfying the prerequisites, the proposed class must fit within a recognized class-action type (Rule 23(b)(1), (2), or (3)).

Some class actions are appropriate because separate actions would risk inconsistent adjudications or impair interests of absent persons. Others are appropriate because the defendant has acted or refused to act on grounds generally applicable to the class, making injunctive or declaratory relief appropriate for the class as a whole.

The most common damages class (Rule 23(b)(3)) requires that common questions predominate over individual questions and that a class action be superior to other available methods. Predominance is more demanding than commonality. It asks whether the common issues are central enough to justify classwide adjudication. Superiority asks whether class treatment is practical and fair compared to alternatives.

Notice and Opt-Out Rights

In damages class actions, class members generally must receive the best notice practicable under the circumstances and an opportunity to opt out. Notice protects due process because absent class members may be bound by the judgment. In some non-damages class actions, opt-out rights may not be required in the same way.

Subject-Matter Jurisdiction in Class Actions

A class action in federal court still requires subject-matter jurisdiction. Federal-question jurisdiction may exist if the class claims arise under federal law. Diversity may exist under ordinary rules or under special class-action statutes (like CAFA) in qualifying cases.

The named plaintiff must have standing. A class action does not eliminate Article III requirements. At least one named plaintiff must have a concrete injury traceable to the defendant and redressable by the court.

Supplemental jurisdiction and class-action statutes may affect the treatment of unnamed class members, amount in controversy, and diversity. For exam purposes, do not assume Rule 23 itself creates federal jurisdiction. It does not.

XI. Severance and Misjoinder

Misjoinder is not ordinarily a ground for dismissing an entire action. The court may drop a party or sever claims to cure joinder problems.

Severance allows claims to proceed separately when joint litigation would be confusing, prejudicial, inefficient, or inconsistent with the joinder rules. Courts have discretion to manage complex cases by separating claims or parties.

This flexibility reinforces the idea that joinder rules are tools for fair and efficient adjudication, not traps designed to destroy claims unnecessarily.

XIII. Bar-Style Analysis Notes

• For claim joinder, ask whether the same plaintiff is joining claims against the same opposing party. Then analyze jurisdiction separately.
• For permissive party joinder, ask whether the claims arise from the same transaction or occurrence and share a common question.
• For counterclaims, classify the claim as compulsory or permissive. Compulsory counterclaims arise from the same transaction or occurrence and are often supported by supplemental jurisdiction. Permissive counterclaims usually need independent jurisdiction.
• For crossclaims, ask whether the claim is against a co-party and arises from the same transaction or occurrence.
• For impleader, ask whether the third-party defendant may be liable to the defending party for all or part of the plaintiff’s claim. Do not use impleader merely to blame a third party.
• For required parties, ask whether the absent person is required, whether joinder is feasible, and whether the action should proceed if joinder is not feasible.
• For intervention, analyze timeliness, interest, impairment, and adequacy for intervention of right. For permissive intervention, look for common questions and lack of undue delay or prejudice.
• For interpleader, identify the stake, stakeholder, competing claimants, and risk of multiple liability.
• For class actions, analyze numerosity, commonality, typicality, adequacy, class type, notice, opt-out rights, predominance, superiority, and jurisdiction.