In pleading to a preceding pleading, a party shall set forth all applicable affirmative defenses and avoidances, including but not limited to accord and satisfaction, arbitration and award, assumption of risk, contributory negligence, comparative fault, state of the art as provided by statute, seller in the stream of commerce as provided by statute, discharge in bankruptcy, duress, estoppel, failure of consideration, fraud, illegality, injury by fellow servant, laches, license, payment, release, res judicata, statute of frauds, statute of limitations, truth in defamation, waiver, and any other matter constituting an avoidance or affirmative defense. A pleading that sets forth an affirmative defense or avoidance shall contain a short and plain statement of the facts showing that the pleader is entitled to the defense or avoidance. When a party has mistakenly designated a defense as a counterclaim or a counterclaim as a defense, the court may treat the pleadings as if there had been a proper designation.
Rule 55.08.Affirmative Defenses.
Part I · Rule 55: Pleadings, Motions and Hearing · Last amended July 1, 2026 · Last verified July 22, 2026
This rule prints two full, separately-dated versions in the official compilation (a pending or recent amendment straddle); both are shown below.
In one sentenceRule 55.08 requires a party responding to a pleading to set out every applicable affirmative defense — including statute of limitations, contributory negligence, comparative fault, estoppel, and fraud — with a short and plain statement of the supporting facts.
Full Text of Rule 55.08
Rule 55.08. Affirmative Defenses. — Effective until July 1, 2026
Rule 55.08. Affirmative Defenses. — Effective July 1, 2026
In pleading to a preceding pleading, a party shall set forth all applicable affirmative defenses and avoidances, including but not limited to accord and satisfaction, right to arbitration, arbitration award, assumption of risk, contributory negligence, comparative fault, state of the art as provided by statute, seller in the stream of commerce as provided by statute, discharge in bankruptcy, duress, estoppel, failure of consideration, fraud, illegality, injury by fellow servant, laches, license, payment, release, res judicata, statute of frauds, statute of limitations, truth in defamation, waiver, and any other matter constituting an avoidance or affirmative defense. A pleading that sets forth an affirmative defense or avoidance shall contain a short and plain statement of the facts showing that the pleader is entitled to the defense or avoidance. When a party has mistakenly designated a defense as a counterclaim or a counterclaim as a defense, the court may treat the pleadings as if there had been a proper designation.
Amendment History
Effective until July 1, 2026
Adopted Jan. 19, 1973, eff. Sept. 1, 1973. Amended June 1, 1993, eff. Jan. 1, 1994.
Effective July 1, 2026
Adopted Jan. 19, 1973, eff. Sept. 1, 1973. Amended June 1, 1993, eff. Jan. 1, 1994; Amended Aug. 12, 2025, eff. July 1, 2026.
Plain-English Summary
Rule 55.08 lists a long set of examples of affirmative defenses and avoidances a party must plead when they apply: accord and satisfaction, arbitration, assumption of risk, contributory negligence, comparative fault, discharge in bankruptcy, duress, estoppel, failure of consideration, fraud, illegality, laches, license, payment, release, res judicata, statute of frauds, statute of limitations, waiver, and more, closed out by a catch-all for any other matter constituting an avoidance or affirmative defense. These are defenses that go beyond denying the plaintiff’s facts outright — they raise new matter that would defeat the claim even if those facts are true.
Pleading an affirmative defense takes the same short-and-plain-statement approach as pleading a claim: the party asserting it must state the facts showing entitlement to the defense, not just name the defense in the abstract. A defense listed by name without any supporting facts doesn’t satisfy the rule.
The rule also has a forgiving side. If a party mistakenly labels a defense as a counterclaim, or a counterclaim as a defense, the court can treat the pleading as if it had been properly designated in the first place — the substance controls over the label.
A version of the rule effective July 1, 2026 makes a small wording change, replacing “arbitration and award” with “right to arbitration, arbitration award,” without altering the rule’s overall structure or its requirement that affirmative defenses be pleaded with supporting facts.
Frequently Asked Questions
What are affirmative defenses under Missouri Rule 55.08?
Defenses that raise new matter beyond a plain denial — such as statute of limitations, release, waiver, estoppel, or fraud — that would defeat the claim even if the plaintiff’s facts are true.
What happens if I don’t plead an affirmative defense?
It can be waived. Rule 55.08 requires that all applicable affirmative defenses and avoidances be set forth in the responsive pleading.
Is the list of affirmative defenses in Rule 55.08 exhaustive?
No. The rule’s list is followed by a catch-all covering any other matter constituting an avoidance or affirmative defense.
What if I mislabel a defense as a counterclaim?
The court can treat the pleading as if it had been properly designated instead of penalizing the mislabeling.
Do I need to plead facts supporting an affirmative defense, or just name it?
Facts are required. The rule calls for a short and plain statement of the facts showing entitlement to the defense.
Source & verification. Rule text and amendment history are
reproduced verbatim from the Missouri State & Federal Court Rules, adopted by the
Supreme Court of Missouri. Last verified July 22, 2026. ·
Official source
Also known as: affirmative defenseaffirmative defenseswaiver of affirmative defensestatute of limitations defensepleading affirmative defenseslist of affirmative defenses