Federal Rule of Civil Procedure 61
Rule 61. Harmless Error
Unless justice requires otherwise, no error in admitting or excluding evidence—or any other error by the court or a party—is ground for granting a new trial, for setting aside a verdict, or for vacating, modifying, or otherwise disturbing a judgment or order. At every stage of the proceeding, the court must disregard all errors and defects that do not affect any party’s substantial rights.
- Rule 61 provides that errors that do not affect a party’s substantial rights are harmless and cannot be grounds for a new trial, setting aside a verdict, or modifying a judgment or order.