Massachusetts Guide to Evidence 2025 Edition MA R EVID § 606

(a) At the Trial. A juror may not testify as a witness before the other jurors at the trial. If a juror is called to testify, the court must give a party an opportunity to object outside the jury's presence.

(b) During an Inquiry into the Validity of a Verdict. During an inquiry into the validity of a verdict, the court may ask the jurors individually to affirm publicly that the verdict as recorded represents their decision. However, a juror may not testify about any statement made or incident that occurred during the jury's deliberations, the effect of anything on that juror's or another juror's vote, or any juror's mental processes concerning a verdict. The court may not receive a juror's affidavit or evidence of a juror's statement on these matters.

(c) Permitted Testimony. A juror may testify about whether