(1) The court shall, in every stage of an action, disregard any error or defect in the pleadings or proceedings which shall not affect the substantial rights of the adverse party.
805.18.Mistakes and omissions; harmless error.
Ch. 805: Trials · Last amended 1997 · Last verified July 15, 2026
In one sentenceSection 805.18 requires courts to disregard procedural errors and defects that do not affect a party’s substantial rights, and bars reversing a judgment or ordering a new trial for jury selection, evidentiary, or procedural error unless the error affected the substantial rights of the party seeking relief.
Full Text of Section 805.18
(2) No judgment shall be reversed or set aside or new trial granted in any action or proceeding on the ground of selection or misdirection of the jury, or the improper admission of evidence, or for error as to any matter of pleading or procedure, unless in the opinion of the court to which the application is made, after an examination of the entire action or proceeding, it shall appear that the error complained of has affected the substantial rights of the party seeking to reverse or set aside the judgment, or to secure a new trial.
Plain-English Summary
Not every misstep in a lawsuit is worth undoing a result over, and Section 805.18(1) states that principle directly: at every stage of an action, the court has to disregard any error or defect in the pleadings or proceedings that does not affect the substantial rights of the adverse party.
Section 805.18(2) carries that same principle into the standard for reversal or a new trial. No judgment can be reversed or set aside, and no new trial can be granted, on the ground of jury selection or misdirection, improper admission of evidence, or an error in pleading or procedure, unless the reviewing court, after examining the entire action or proceeding, concludes that the error affected the substantial rights of the party seeking to reverse the judgment or secure a new trial.
Frequently Asked Questions
Does every mistake in a pleading or during trial require the court to act on it?
No. Section 805.18(1) requires the court to disregard any error or defect in the pleadings or proceedings that does not affect the substantial rights of the adverse party.
Can a judgment be reversed just because the wrong evidence was admitted?
Not by itself. Section 805.18(2) requires the reviewing court, after examining the entire action or proceeding, to find that the error affected the substantial rights of the party seeking to reverse the judgment or secure a new trial.
Does this harmless-error standard apply to jury selection errors too?
Yes. Section 805.18(2) lists selection or misdirection of the jury among the grounds subject to the substantial-rights standard, alongside improper admission of evidence and errors of pleading or procedure.
At what stage of a case does the harmless-error rule apply?
Section 805.18(1) applies “in every stage of an action,” so it is not confined to trial or to any single phase of the proceeding.
Who has to show the error affected substantial rights?
The party seeking to reverse or set aside the judgment or to secure a new trial, based on the reviewing court’s examination of the entire action or proceeding.
Amendment History
History: Sup. Ct. Order, 67 Wis. 2d 585, 714 (1975); Sup. Ct. Order No. 96-08, 207 Wis. 2d xv (1997).
Source & verification. Section text and official notes are
reproduced verbatim from the Wisconsin Statutes, published by the
Wisconsin Legislature (Legislative Reference Bureau). Last verified July 15, 2026.
· Official source
Also known as: harmless error wisconsin civil proceduresubstantial rights standard wisconsindisregard procedural defect wisconsinreversible error standard wisconsin