The rules of civil procedure or the code of civil procedure in state and federal courts usually permit a party to a civil lawsuit (a litigant) to amend its pleadings.
A plaintiff can amend the complaint or petition to assert new claims or causes of action before or during trial, subject to certain limitations—and the defendant can amend the answer to the lawsuit to assert new defenses to the plaintiff's claims before or during trial, subject to certain limitations.
In Texas, the rules governing the amendment of pleadings in civil lawsuits are outlined in the Texas Rules of Civil Procedure. Rule 63 allows parties to amend their pleadings, such as complaints or answers, to assert new claims or defenses. Amendments can be made without leave of court if they are filed at least seven days before trial. If the amendment is filed later than this, the opposing party may seek a continuance if the amendment presents a surprise. Additionally, even if an amendment is made during the trial, the court has the discretion to consider it if it does not change the nature of the trial or operate as a surprise to the opposing party. At the federal level, Rule 15 of the Federal Rules of Civil Procedure permits parties to amend their pleadings with the court's leave, and the court should freely give permission when justice so requires. Amendments before trial are typically allowed if they do not cause undue delay or prejudice to the other party. After a certain point, such as after a responsive pleading or a motion for summary judgment, leave of court is required to amend a pleading.
