Impleader under Federal Rule of Civil Procedure 14 lets a defendant pull a non-party into an existing lawsuit when that outsider may owe the defendant reimbursement for some or all of what the plaintiff is claiming. The defendant becomes the “third-party plaintiff,” files a new complaint against the outsider (the “third-party defendant”), and the court sorts out the related liability in one case instead of a second one later. The mechanism only works when a specific legal relationship exists between the defendant and the outsider, and misreading that requirement is the fastest way to have a third-party complaint tossed.
The Derivative Liability Requirement
Impleader is not a tool for pointing fingers. Rule 14(a)(1) allows a defendant to bring in a third party only “who is or may be liable to it for all or part of the claim against it.”1Legal Information Institute. Federal Rules of Civil Procedure Rule 14 – Third-Party Practice Courts enforce that language strictly. The third-party defendant’s obligation must flow from the outcome of the original case. If the defendant loses, the third-party defendant owes the defendant something. If the defendant wins, the third-party claim goes away.
A defendant cannot implead someone just because that person might be independently liable to the plaintiff. If the real argument is “they did it, not me,” that belongs in the answer as a defense, not in a third-party complaint. Courts routinely strike impleader claims where the defendant is trying to substitute a different tortfeasor rather than establish a secondary obligation running back to the defendant.
Indemnity and Contribution
Two theories support most impleader claims, and they work differently.
Indemnity shifts the entire loss from one party to another. The most common form is contractual: a written agreement says one party will cover the other’s losses. A general contractor whose subcontract requires the subcontractor to indemnify it for injuries caused by the subcontractor’s work can implead the subcontractor when the owner sues. Indemnity can also arise without a contract in situations where equity demands it, such as an employer held vicariously liable for an employee’s negligence.
Contribution divides the loss among multiple responsible parties rather than shifting all of it. If two companies jointly caused a spill and the plaintiff sues only one, the sued company can implead the other to force a fair split. The point is that the defendant doesn’t get stuck paying for someone else’s share of the harm.
How Rule 14 Compares to Other Joinder Rules
The test for impleader is narrower than most other joinder rules. Crossclaims under Rule 13(g) and permissive joinder under Rule 20 use a “same transaction or occurrence” standard, so factual overlap is enough. Impleader asks a single question: is this non-party potentially liable to the defendant for the defendant’s own liability?1Legal Information Institute. Federal Rules of Civil Procedure Rule 14 – Third-Party Practice That’s a much tighter filter.
The distinction matters when choosing strategy. A defendant who wants to blame a co-defendant already in the case uses a crossclaim, not impleader. A defendant who wants to bring in a new party on a “same transaction” theory without derivative liability needs Rule 20 joinder, not Rule 14.
The 14-Day Window and Late Motions
A defendant can file a third-party complaint as a matter of right within 14 days of serving the original answer. No motion, no court permission.1Legal Information Institute. Federal Rules of Civil Procedure Rule 14 – Third-Party Practice The window is short by design, so the case doesn’t expand after everyone has settled into a litigation plan.
After 14 days, the defendant must move for leave to implead. Courts weigh four factors: prejudice to the original plaintiff, whether the new claim would complicate the issues at trial, the likelihood of delay, and how promptly the defendant moved once the basis for impleader became clear. Courts generally construe Rule 14 liberally in favor of allowing impleader because it avoids duplicate lawsuits, but that liberal reading has limits. A defendant who waits until the discovery deadline is approaching or the trial date is set will face serious skepticism, and courts will not delay trial for a claim that could have been filed months earlier.
Filing and Serving the Third-Party Complaint
The third-party complaint is a standalone pleading filed in the same case. It must identify the third-party defendant by exact legal name and plead the derivative liability link with enough detail to meet federal pleading standards, referencing the specific contract clause, insurance provision, or legal relationship that creates the indemnity or contribution obligation.
Because the pleading is filed within an existing case rather than starting a new one, it generally does not require a separate filing fee. The statutory fee under 28 U.S.C. § 1914 applies to “parties instituting any civil action,” which means the original case.2Office of the Law Revision Counsel. 28 USC 1914 Local rules can add miscellaneous fees in some districts, so check them.
Once the clerk issues a summons, service follows Rule 4. Any person at least 18 years old who is not a party can serve the documents; most litigants use a professional process server, the U.S. Marshals Service, or a waiver of service under Rule 4(d). If service isn’t completed within 90 days of filing, the court can dismiss the third-party claim without prejudice.3Legal Information Institute. Federal Rules of Civil Procedure Rule 4 – Summons Proof of service then gets filed with the court, which starts the response clock.
How the Third-Party Defendant Responds
The third-party defendant has 21 days after service to respond.4Legal Information Institute. Federal Rules of Civil Procedure Rule 12 – Defenses and Objections: When and How Presented The response can be an answer that raises defenses to the derivative liability theory, or a Rule 12 motion to dismiss arguing that the complaint fails to state a valid basis for indemnity or contribution, or that the court lacks jurisdiction.
Rule 14(a)(2) also requires the third-party defendant to bring any compulsory counterclaim against the third-party plaintiff under Rule 13(a), and allows permissive counterclaims under Rule 13(b) and crossclaims against other third-party defendants under Rule 13(g).1Legal Information Institute. Federal Rules of Civil Procedure Rule 14 – Third-Party Practice Getting impleaded pulls a party into the full web of the case, not just the derivative claim.
The third-party defendant also gets a useful defensive tool: it can assert against the original plaintiff any defense the third-party plaintiff has to the plaintiff’s claim.1Legal Information Institute. Federal Rules of Civil Procedure Rule 14 – Third-Party Practice If the original defendant forgot to argue that the statute of limitations has run, the third-party defendant can raise it. That protects the third-party defendant from paying on a derivative claim the original defendant should have defeated. The third-party defendant can also assert claims directly against the plaintiff, as long as those claims arise from the same transaction or occurrence as the original complaint.
Claims by the Original Plaintiff
Rule 14(a)(3) lets the original plaintiff assert claims directly against the third-party defendant, provided those claims arise from the same transaction or occurrence underlying the original suit.1Legal Information Institute. Federal Rules of Civil Procedure Rule 14 – Third-Party Practice Once the plaintiff does that, the third-party defendant must raise any compulsory counterclaims and Rule 12 defenses in response. Every related dispute ends up resolved in a single proceeding, which is the point of the rule.
When a Plaintiff Can Implead
Rule 14(b) gives the plaintiff the same tool when a counterclaim is filed against it. The plaintiff can bring in a third party on the same conditions that would allow a defendant to do so.1Legal Information Institute. Federal Rules of Civil Procedure Rule 14 – Third-Party Practice The derivative liability requirement still applies, and so does the 14-day timing rule. This comes up less often, but if a defendant files a substantial counterclaim and the plaintiff has an indemnity or contribution right against someone outside the case, Rule 14(b) is the vehicle.
Fourth-Party Practice
The chain doesn’t stop at three parties. Rule 14(a)(5) lets a third-party defendant implead someone who may be liable to it for the third-party claim.1Legal Information Institute. Federal Rules of Civil Procedure Rule 14 – Third-Party Practice Construction litigation is the classic setting: owner sues general contractor, who impleads a subcontractor, who impleads a materials supplier, each link resting on its own contractual indemnity clause. Courts allow it when the claims are legitimate but will push back when the case starts to look unmanageable.
Jurisdiction Traps
Adding parties raises jurisdiction questions that can quietly kill a third-party claim.
Supplemental Jurisdiction
The defendant’s claim against the third-party defendant generally falls within supplemental jurisdiction under 28 U.S.C. § 1367(a), so no independent jurisdictional basis is needed for the impleader claim itself. The trap sits on the plaintiff’s side. In diversity cases under 28 U.S.C. § 1332, the court cannot exercise supplemental jurisdiction over claims by the plaintiff against a Rule 14 third-party defendant when doing so would destroy diversity.5Office of the Law Revision Counsel. 28 U.S. Code 1367 – Supplemental Jurisdiction A plaintiff who wants to assert claims against the third-party defendant in a diversity case needs an independent jurisdictional basis: complete diversity from that party with more than $75,000 at stake, or a federal question. One workaround exists. If the third-party defendant asserts a compulsory counterclaim against the plaintiff under Rule 13(a) first, the plaintiff’s compulsory counterclaim in response doesn’t need independent jurisdiction.
The 100-Mile Bulge Rule
Federal courts normally require sufficient contacts with the forum state to exercise personal jurisdiction. Rule 4(k)(1)(B) carves out an exception for impleader: a party joined under Rule 14 can be served anywhere within 100 miles of the courthouse where the summons issued, even across state lines.3Legal Information Institute. Federal Rules of Civil Procedure Rule 4 – Summons This matters most in cases filed near state borders, where the third-party defendant would otherwise sit just outside the court’s reach.
Severing, Striking, and Bifurcating
Impleader is not permanent. Under Rule 14(a)(4), any party, including the original plaintiff, can move to strike the third-party claim or ask for a separate trial on the third-party issues. Courts use this authority when the new claim would confuse the jury, overwhelm the original dispute with tangential issues, or prejudice the plaintiff. Judges also act on their own. A court may keep the third-party complaint but bifurcate: the jury first decides the plaintiff’s claim against the defendant, then the court addresses the defendant’s claim against the third-party defendant. That preserves the efficiency of impleader while keeping the original trial clean.
What Settlement Does to the Third-Party Claim
If the original plaintiff and defendant settle, the third-party claim doesn’t automatically survive. Under 28 U.S.C. § 1367(c)(3), a district court may decline to exercise supplemental jurisdiction over remaining claims once all claims providing original jurisdiction have been dismissed.5Office of the Law Revision Counsel. 28 U.S. Code 1367 – Supplemental Jurisdiction Settlement between the original parties often leads the court to dismiss the third-party claim, leaving the former defendant to pursue any remaining indemnity or contribution rights in a new action.
The outcome turns on whether the third-party claim has its own jurisdictional footing. If the third-party defendant is diverse from the third-party plaintiff and the amount in controversy is met, the court can keep the claim alive after the original dispute resolves. If the claim exists only through supplemental jurisdiction, the court has discretion, and most courts let it go. Anyone anticipating a possible settlement should factor that risk into strategy from the start.