Mass. R. Evid. 603
Before testifying, a witness must give an oath or affirmation to testify truthfully. It must be in a form designed to impress that duty on the witness's conscience.
Mass. Guid. Evid. 603
This section is taken from Fed. R. Evid. 603 and Proposed Mass. R. Evid. 603 and is consistent with Massachusetts law. See G. L. c. 233, §§ 15-19. See also Mass. R. Civ. P. 43(d) ("Whenever under these rules an oath is required to be taken, a solemn affirmation under the penalties of perjury may be accepted in lieu thereof."). "Although taking [the traditional] oath is the customary method for signifying one's recognition that consequences attend purposeful falsehood, it is not the only method for doing so. The law requires some affirmative representation that the witness recognizes the obligation to tell the truth. See G. L. c. 233, §§ 17-19." Adoption of Fran, 54 Mass. App. Ct. 455, 467 (2002). A judge is not permitted to waive an oath or affirmation. Commonwealth v. Stewart, 454 Mass. 527, 531 (2009).
"A child witness does not have to understand fully the obligation of an oath, but must show a general awareness of the duty to be truthful and the difference between a lie and the truth." Commonwealth v. Ike I., 53 Mass. App. Ct. 907, 909 (2002). "With children, recognition of that obligation [to tell the truth] sometimes is more effectively obtained through careful questioning of the child than through recitation of what to the child may be a meaningless oath or affirmation." Adoption of Fran, 54 Mass. App. Ct. at 467 n.17. A judge's finding that a child understands the difference between the truth and lying and the importance of testifying truthfully "effectively serve[s] the underlying purpose of the oath, and no more [can] be reasonably required of an infant deemed competent to testify, but manifestly lacking in theological understanding." Commonwealth v. McCaffrey, 36 Mass. App. Ct. 583, 590 (1994).