Rule 61.Harmless Error

Rule 61 sets a filter that applies across the entire life of a case. No error in admitting or excluding evidence, and no other error by the court or a party, counts as grounds for granting a new trial, setting aside a verdict, or vacating, modifying, or otherwise disturbing a judgment or order — unless justice requires otherwise. The companion sentence states the flip side of the same idea as an instruction to the court: at every stage of the proceeding, the court must disregard errors and defects that do not affect a party's substantial rights.

The rule functions as a backstop to the more specific remedies in Rules 59 and 60. Those rules let a party seek a new trial or relief from a judgment on particular grounds, but Rule 61 makes clear that identifying some error in the proceedings is not, by itself, enough. The error has to have affected a substantial right — meaning it mattered to the outcome — before it can support undoing a verdict or judgment. An error that a party properly objected to, including under the preservation requirements in Rule 51 for jury instructions, can still turn out to be harmless under this standard.

Because the rule speaks to “every stage of the proceeding,” it is not limited to trial evidence rulings. It applies wherever an error or defect might otherwise be raised as a reason to disturb what the court has done, reinforcing that DC civil practice looks past technical missteps and focuses on whether an error changed a party's substantial rights.