This summary is not the rule. The rule text controls.
If a mistake happens during a trial, like letting in a piece of evidence that shouldn't have been allowed, that mistake alone usually isn't enough to throw out the result. Courts understand that trials aren't perfect and small errors happen. The question is whether the mistake actually hurt someone's case in a meaningful way.
If the error didn't change the outcome or affect someone's basic rights, the court will just ignore it and let the judgment or verdict stand. Judges are required to overlook small slip-ups that don't really matter to the final result. This keeps cases from being reopened or overturned over minor issues that had no real impact.
The only time this rule doesn't apply is when fixing the mistake is truly necessary for justice. So if an error was serious enough that it likely changed the outcome or unfairly harmed one side, a court can step in and correct it, whether that means ordering a new trial or changing the judgment. But if the mistake was harmless, the case moves forward as decided.
