Fed. R. Civ. P. 61
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.
28 APPENDIX U.S.C. § 61
NOTES OF ADVISORY COMMITTEE ON RULES-1937A combination of U.S.C., Title 28, §§391 [see 2111] (New trials; harmless error) and [former] 777 (Defects of form; amendments) with modifications. See McCandless v. United States, 298 U.S. 342 (1936). Compare [former] Equity Rule 72 (Correction of Clerical Mistakes in Orders and Decrees); and last sentence of [former] Equity Rule 46 (Trial-Testimony Usually Taken in Open Court-Rulings on Objections to Evidence). For the last sentence see the last sentence of [former] Equity Rule 19 (Amendments Generally).
COMMITTEE NOTES ON RULES-2007 AMENDMENT The language of Rule 61 has been amended as part of the general restyling of the Civil Rules to make them more easily understood and to make style and terminology consistent throughout the rules. These changes are intended to be stylistic only.