Fed. R. Civ. P. 15 — Amended and Supplemental Pleadings
Last verified: May 19, 2026 · U.S. Courts — FRCP.
Rule Text — Key Provisions
(a)(1) Amendments as a matter of course. A party may amend its pleading once within 21 days after serving it, or 21 days after service of a responsive pleading or a Rule 12 motion, whichever is earlier.
(a)(2) Other amendments. A party may amend with written consent of the opposing party or with leave of court — “the court should freely give leave when justice so requires.”
(b) Amendments during and after trial. If issues not raised in the pleadings are tried by express or implied consent, they are treated as if raised in the pleadings.
(c) Relation back of amendments. An amendment relates back to the original date of pleading if: (A) the law providing the limitations period allows it; (B) the amendment asserts a claim arising out of the same conduct, transaction, or occurrence; or (C) the amendment changes the party against whom a claim is asserted and certain notice requirements are met within 90 days after filing.
Full text: law.cornell.edu/rules/frcp/rule_15.
Plain English
Rule 15 lets you fix your complaint. Within the first 21 days, you can amend once without permission. After that, you need leave of court — and federal courts grant it freely. The big issue is relation back: if you discover a new claim or the wrong defendant after the statute of limitations runs, Rule 15(c) sometimes lets the amendment count as though filed on the original date.
Key Cases & Authority
- Foman v. Davis, 371 U.S. 178 (1962) — Five-factor test for denying leave to amend: undue delay, bad faith, repeated failures to cure deficiencies, undue prejudice, and futility.
- Krupski v. Costa Crociere S.p.A., 560 U.S. 538 (2010) — Relation back under 15(c)(1)(C) turns on what the new defendant knew or should have known about the original misidentification, not the plaintiff’s diligence in discovering the error.
- Schiavone v. Fortune, 477 U.S. 21 (1986) — Older relation-back framework, partially superseded by the 1991 amendment to Rule 15(c). Still cited for the policy concerns about misidentified defendants.
- Beeck v. Aquaslide ‘N’ Dive Corp., 562 F.2d 537 (8th Cir. 1977) — Leading appellate case on amendments allowed after admissions — court must weigh prejudice to non-moving party.
Florida Parallel
Fla. R. Civ. P. 1.190 — Florida’s amendment rule follows the federal liberal-grant standard. Florida relation-back doctrine for misidentified defendants tracks Krupski.
About this rule walkthrough
Part of The Federal Rule Book, hosted by John M. Phillips — Board Certified Civil Trial Lawyer, Court TV analyst, admitted in 8 states + 9 federal districts + SCOTUS.
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Educational only — not legal advice.
Rule Text (verbatim from the Florida Supreme Court)
(a)(1) A party may amend its pleading once as a matter of course within 21 days after serving it, or 21 days after service of a responsive pleading or a Rule 12 motion, whichever is earlier.
(a)(2) In all other cases, a party may amend with the opposing party’s written consent or with leave of court. The court should freely give leave when justice so requires.
(c) An amendment relates back to the original date of pleading if: (A) the law providing the limitations period allows it; (B) the amendment asserts a claim arising out of the same conduct, transaction, or occurrence; or (C) it changes the party against whom a claim is asserted and certain notice requirements are met within 90 days.
Educational reference. This page summarizes a Federal Rule of Civil Procedure for educational purposes. It is not legal advice. Federal procedural rules can change — always verify the current text at uscourts.gov before relying on this summary in any case.
What this rule means in plain English
Rule 15 lets you fix your complaint. Within 21 days you can amend once without permission. After that you ask the court — federal courts grant leave freely. The big issue is relation back. If you discover a new claim or wrong defendant after the statute of limitations runs, Rule 15(c) sometimes lets the amendment count as filed on the original date. Krupski v. Costa Crociere is the modern test.