Voters who cast ballots may not be asked and may not disclose their vote in any proceeding unless the court finds fraud or intentional wrongdoing.
Mass. Guid. Evid. 516
This section is derived from McCavitt v. Registrars of Voters, 385 Mass. 833, 848-849 (1982), in which the court held "that the right to a secret ballot is not an individual right which may be waived by a good faith voter." Id. at 849.
Section 511, Privilege Against Self-Incrimination.