Harmless error refers to violations of procedural rules or
constitutional guarantees that are not
prejudicial, i.e. do not affect the ultimate outcome of the case.
Federal Rules of Civil Procedure
Rule 61. Harmless Error
The court at every stage of the proceeding must disregard any error or defect in the proceeding which does not affect the substantial rights of the parties.
Federal Rules of Criminal Procedure
Rule 52(a). Harmless and Plain Error.
Harmless error. Any error, defect, irregularity, or variance that does not affect substantial rights must be disregarded.
If an
appellant shows that the lower court or agency committed
error during the course of the proceedings below, the appellant is entitled to
relief (including
reversal and
remand) to correct the error, unless the
appellee shows that the error is harmless.