Final answer:
The rule that provides that harmless errors during trial in civil or criminal cases do not require a reversal of the judgment by an appellate court is known as the purged taint exception.
Step-by-step explanation:
The rule that provides that harmless errors during trial in civil or criminal cases do not require a reversal of the judgment by an appellate court is known as the purged taint exception. This rule allows the court to disregard certain errors if they do not have a significant impact on the outcome of the trial. This means that even if errors occurred during the trial process, the judgment can still stand if those errors were harmless.