Massachusetts General Laws Part III. Courts, Judicial Officers and Proceedings in Civil Cases (Ch. 211-262) Ch. 231, § 119

No error in either the admission or the exclusion of evidence and no error or defect in any ruling or order or anything done or omitted by the trial court or by any of the parties is ground for modifying or otherwise disturbing a judgment or order unless the appeals court or the supreme judicial court deems that the error complained of has injuriously affected the substantial rights of the parties. If either court finds that the error complained of affects only one or some of the issues or parties involved it may affirm the judgment as to those issues or parties unaffected and may modify or reverse the judgment as to those affected.