(a) Generally. Every person is competent to be a witness, except as otherwise provided by statute or other provisions of the Massachusetts common law of evidence.

(b) Rulings. A person is competent to be a witness if he or she has

(1) the general ability or capacity to observe, remember, and give expression to that which he or she has seen, heard, or experienced, and

(2) an understanding sufficient to comprehend the difference between truth and falsehood, the wickedness of the latter, and the obligation and duty to tell the truth, and, in a general way, belief that failure to perform the obligation will result in punishment.

(c) Preliminary Questions. While the competency of a witness is a preliminary question of fact for the judge, questions of witness credibility are to be resolved by the trier of fact.

NOTE

Subsection (a). This subsection is derived from G. L. c. 233, § 20. See Commonwealth v. Monzon, 51 Mass. App. Ct. 245, 248–249, 744 N.E.2d 1131, 1135 (2001). A person otherwise competent to be a witness may still be disqualified from testifying. See, e.g., G. L. c. 233, § 20 (with certain exceptions, “neither husband nor wife shall testify as to private conversations with the other”; “neither husband nor wife shall be compelled to testify in the trial of an indictment, complaint or other criminal proceeding against the other”; “defendant in the trial of an indictment, complaint or other criminal proceeding shall, at his own request . . . be allowed to testify”; and “an unemancipated, minor child, living with a parent, shall not testify before a grand jury, trial of an indictment, complaint or other criminal proceeding, against said parent”). See also Section 504, Spousal Privilege and Disqualification; Parent-Child Disqualification; Section 511, Privilege Against Self-Incrimination. Cf. Mass. R. Civ. P. 43(a) (witness testimony, and assessment of the competency of a witness, must be done orally in open court).

Subsection (b). This subsection is taken nearly verbatim from Commonwealth v. Allen, 40 Mass. App. Ct. 458, 461, 665 N.E.2d 105, 107–108 (1996). This test applies to all potential witnesses. Commonwealth v. Brusgulis, 398 Mass. 325, 329, 496 N.E.2d 652, 655 (1986). Neither the inability of a witness to remember specific details of events nor inconsistencies in the testimony render the witness incompetent to testify, so long as the witness demonstrates “the general ability to observe, remember and recount.” Commonwealth v. Trowbridge, 419 Mass. 750, 755, 647 N.E.2d 413, 418 (1995); Commonwealth v. Thibeault, 77 Mass. App. Ct. 419, 424–‌428, 931 N.E.2d 1008, 1013–‌1015 (2010) (six year old permitted to testify about incidents that occurred when she was five despite inconsistencies in her ability to observe, remember, and recount facts and her initial difficulty with concept of a promise in connection with duty to tell the truth). See Commonwealth v. Gamache, 35 Mass. App. Ct. 805, 806–‌809, 626 N.E.2d 616, 618–620 (1994) (five year old permitted to testify about incidents that allegedly took place when the child was twenty-one and thirty-‌three months old despite inconsistencies and her inability to recall every detail in her testimony). “The tendency, moreover, except in quite clear cases of incompetency, is to let the witness testify and have the triers make any proper discount for the quality of her understanding” (quotations omitted). Commonwealth v. Whitehead, 379 Mass. 640, 656, 400 N.E.2d 821, 833–834 (1980). See, e.g., Commonwealth v. Brusgulis, 398 Mass. at 329, 496 N.E.2d at 655 (child); Commonwealth v. Sires, 370 Mass. 541, 546, 350 N.E.2d 460, 464 (1976) (alcoholic); Commonwealth v. Aitahmedlamara, 63 Mass. App. Ct. 76, 78, 823 N.E.2d 408, 410 (2005) (developmentally disabled); Commonwealth v. Hiotes, 58 Mass. App. Ct. 255, 256, 789 N.E.2d 179, 180 (2003) (mental illness).

Subsection (c). The initial segment of this subsection is derived from Demoulas v. Demoulas, 428 Mass. 555, 562–563, 703 N.E.2d 1149, 1158 (1998); the remainder of the subsection is derived from Commonwealth v. Jackson, 428 Mass. 455, 466, 702 N.E.2d 1158, 1165–1166 (1998). The question of the competency of a potential witness is within the discretion of the trial judge, who has “wide discretion . . . to tailor the competency inquiry to the particular circumstances and intellect of the witness.” Commonwealth v. Brusgulis, 398 Mass. 325, 329–330, 496 N.E.2d 652, 655 (1986). When competency is challenged, a judge usually conducts a voir dire examination of the potential witness, but may require a physician or other expert to examine the potential witness’s mental condition where appropriate. Demoulas v. Demoulas, 428 Mass. at 563, 703 N.E.2d at 1158. See G. L. c. 123, § 19; G. L. c. 233, § 23E. Cf. Mass. R. Civ. P. 43(a) (witness testimony, and assessment of the competency of a witness, must be done orally in open court). “Although competency must of course be determined before a witness testifies, the judge may reconsider his decision, either sua sponte or on motion, if he entertains doubts about the correctness of the earlier ruling.” Commonwealth v. Brusgulis, 398 Mass. at 331, 496 N.E.2d at 656.

Competency of Criminal Defendant. A defendant in a criminal case is competent so long as the defendant has a “sufficient present ability to consult with his [or her] lawyer with a reasonable degree of rational understanding and . . . a rational as well as factual understanding of the proceedings.” Commonwealth v. Hung Tan Vo, 427 Mass. 464, 468–469, 693 N.E.2d 1374, 1378 (1998), quoting Commonwealth v. Vailes, 360 Mass. 522, 524, 275 N.E.2d 893, 895 (1971), quoting Dusky v. United States, 362 U.S. 402, 402 (1960). The trial judge has a duty to act sua sponte whenever there is “a substantial question of possible doubt” as to the defendant’s competency to stand trial. See Commonwealth v. Hill, 375 Mass. 50, 62, 375 N.E.2d 1168, 1174–‌1175 (1978).

It is not necessary to suspend all pretrial proceedings because a defendant is not competent. See Abbott A. v. Commonwealth, 458 Mass. 24, 33, 933 N.E.2d 936, 945 (2010) (concluding it is not a per se violation of due process for the Commonwealth to proceed against incompetent person at bail hearing or dangerousness hearing). Contra Commonwealth v. Torres, 441 Mass. 499, 505–507, 806 N.E.2d 895, 900–901 (2004) (stating due process may be violated if defense counsel is unable to communicate at all with client during bail hearing or hearing on rendition).