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.Harmless error
Title VIII: Post-Judgment Procedure · Last amended July 1, 2016 · Last verified July 14, 2026
In one sentenceRule 61 is Idaho's harmless error rule, barring a new trial or a disturbed judgment over any error that did not affect a party's substantial rights.
Full Text of Rule 61
Amendment History
(Adopted March 1, 2016, effective July 1, 2016.)
Plain-English Summary
Trials are rarely flawless, and Rule 61 recognizes that not every misstep deserves a do-over. Whether the error involves admitting or excluding evidence, or some other mistake by the court or a party, it cannot justify a new trial, setting aside a verdict, or disturbing a judgment unless justice truly requires it. The rule asks judges to look past technical missteps and focus on whether the outcome would have been any different.
This standard applies at every stage of a case, not just after a verdict. Courts must disregard errors and defects that do not touch a party's substantial rights, meaning the challenging party generally must show the mistake affected the result, not just that a rule was broken along the way.
Frequently Asked Questions
What is the "harmless error" rule?
It is the principle in Rule 61 that an error during a case, including mistakes in admitting or excluding evidence, does not justify a new trial or a changed judgment unless it affected a party's substantial rights.
Does every evidentiary mistake require a new trial?
No. Even if a court wrongly admitted or excluded evidence, Rule 61 blocks a new trial or a disturbed judgment unless the mistake affected a substantial right and justice requires a remedy.
What does it mean for an error to affect a "substantial right"?
It generally means the error was significant enough that it likely influenced the outcome of the case, rather than being a technical or inconsequential misstep.
At what point in a case does Rule 61 apply?
The rule applies at every stage of the proceeding, meaning courts are meant to disregard harmless errors and defects throughout the case, not only when reviewing a final verdict or judgment.
Who has to show that an error was harmful rather than harmless?
The party challenging the outcome bears the practical burden of showing the error affected a substantial right, since Rule 61 directs courts to disregard errors that did not.
Source & verification. Rule text
are reproduced verbatim from the Idaho Rules of Civil Procedure, adopted by the
Supreme Court of Idaho. Last verified July 14, 2026. ·
Official source
Also known as: harmless error ruleharmless error idahosubstantial rights standardevidentiary error new trialrule 61 idaho