Amending a Petition/Lawsuit

In Missouri, a “Petition” is the lawsuit filed by a plaintiff requesting relief against a defendant (often in the form of money damages). It is called a “Complaint” in federal court, but they’re functionally the same thing. It is quite common for a petition to be amended to account for facts uncovered in discovery or correct other legal or factual matters. Courts are required to permit a party to amend the lawsuit/petition when “justice so requires.” Rule 55.33(a). To help navigate this vague standard, courts consider the following factors when deciding whether to permit a party to amend: (1) hardship to the plaintiff if leave to amend is not granted; (2) the plaintiff’s failure to include any new matters in the previous petition; (3) the timeliness of plaintiff’s application; (4) whether the amendment could cure any defects of the previous petition; and (5) injustice to the defendant who opposes the motion. Miles ex rel. Miles v. Rich, 347 S.W.3d 477, 485 (Mo. Ct. App. 2011). “Prejudice is not measured by whether one party or the other would stand to suffer financial loss as a result of the court ruling.” Oak Bluff Condominium Owner’s Ass’n, Inc. v. Oak Bluff Partners, Inc., 263 S.W.3d 714, 719 (Mo. Ct. App. 2008) “Instead, prejudice suffered by the non-moving party is measured by whether a party is deprived of a legitimate claim or defense because the motion for leave to amend caught that party by surprise after it had developed its strategy.” Id.
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