dissenting in part.
It is disturbing to me that in evaluating the credibility of an eight-year-old boy, the critical and uncorroborated witness in this case, the jury is not entitled to hear the opinion of an independent clinical psychologist who, wholly apart from this criminal prosecution, had been assessing the boy’s truthfulness by checking his stories over a nine-month period. I agree with the Court that the Maine Rules of Evidence seem to compel that result, but in doing so they are fundamentally unfair.
I do not agree with the Court’s faulting of Dr. Sobchuk’s testimony under M.R. Evid. 702 for what is basically an inadequate foundation — i.e. that the defense did not qualify Dr. Sobchuk to give the opinion sought. Here, the State made no objection on this ground at trial and the trial court made a clear finding that Dr. Sobchuk was qualified. Rule 702, though mentioned in passing, was simply not the basis for the trial court’s ruling excluding this testimony,1 the transcript demonstrates that neither trial counsel nor the trial court considered it to be an issue, and the defendant therefore never had reason to beef up his proffer.
The reason Dr. Sobchuk’s testimony is inadmissible under the Maine Rules of Evidence is that the Rules simply do not permit opinion testimony on credibility. See M.R.Evid. 608, 405; State v. Arnold, 421 A.2d 932, 937-38 (Me.1980). In this respect, they differ from both the federal model and an earlier draft of the Maine Rules.2 See Fed.R.Evid. 405(a); M.R.Evid. 405(a) (Tent. Draft Dee. 1974). As Maine commentators have observed, Maine Rule 405(a) “does not, as the Federal Rule does, sanction opinion testimony.... [T]he only allowable method of proof is by reputation evidence.” Field & Murray, Maine Evidence § 405.1 at 115 (1987). The Advisory Committee found “some justification” for permitting opinion testimony, reasoning that there is not much difference between saying that someone’s reputation is good and actually vouching for the defendant. The Committee ultimately excluded it, however, because of “the risk that wholesale allowance of opinion testimony would tend to turn a trial into a swearing contest between conflicting character witnesses.” M.R.Evid. 405 Advisory Committee Note published Feb. 2, 1976, Field & Murray at 114. This has turned out to be an unfounded concern. There is no evidence that federal trials, where opinion testimony on credibility is permitted, have turned into swearing contests of this sort. Maine Rule of Evidence 403, identical to Federal Rule of Evidence 403, provides sufficient control to the trial courts to avoid such a develop*348ment. As a result of the blanket exclusion, on the other hand,3 opportunities for challenging the credibility of a child witness are severely limited. The evidence of reputation permitted by Rules 405(a) & 608(a) will seldom be available in the case of a young child, particularly if the child has moved frequently as in troubled families. (Here the father testified that he and the children moved 15 to 20 times in the years before Calvin, Jr. was six or seven years old.) Although Rule 608(b) permits a lawyer, with the specific permission of the court, to inquire on cross-examination concerning specific instances that may bear upon credibility or untruthfulness, that provision obviously is of small assistance to a lawyer dealing with an eight-year-old on the stand in front of a jury. In short, without opinion testimony there really is no effective way to deal with the credibility of a child witness except through separate eyewitness testimony to the incident, something that is almost always unavailable in sexual abuse allegations.
I believe most ordinary citizens would consider Dr. Sobchuk’s opinion highly relevant in evaluating the testimony of eight-year-old Calvin, Jr. The Department of Human Services referred the boy to Dr. Sobchuk because he was “acting out at school.” One of the principal problems reported was that Calvin, Jr. was lying both at school and at home. Dr. Sobchuk conducted hour-long sessions with the youngster about three times a month for a total of 24 sessions running until June of 1986. (Calvin made his first accusation concerning his father in November of 1986 and the trial occurred in November of 1987.) Dr. Sobchuk gained Calvin, Jr.’s confidence and engaged him in conversation about a wide range of matters. He then investigated the truth of a large number of incidents reported by the boy in various categories. He found that “Calvin, with few exceptions, was not telling the truth.” On Calvin, Jr.’s ability to separate fact from fiction,
A. He was highly suspect. He was often times mixing facts and fantasy. He aimed to please the examiner in terms of whatever it is he felt the examiner wanted to hear.
Q. Now is there a concept called pathological lying?
A. There is a concept called pathological lying.
Q. Did you make any conclusion about that vis-a-vis Calvin Woodburn, Jr.?
A. That’s a rather harsh concept to draw in light of Calvin. However, for the most part I think it applies in that he will tell lies, show very little remorse or not have any — show very little signs or understanding of the consequences.
Dr. Sobchuk’s negative opinion on credibility was excluded concerning a young boy who, during his voir dire for competence, (in addition to appropriate testimony) answered yes to the two questions “If you say something and it helps you out, does that make it true?” and “if you know what somebody wants you to say and you say it, does that make it true?”4 Regardless of whether Dr. Sobchuk’s opinion testimony is considered expert or lay, scientific or amateur,5 it is difficult to understand why this *349opinion, developed in a nonpartisan context over several months of investigation, is inferior to the standard testimony concerning a witness’s reputation for credibility that would be admissible under Rule 608(a).6
I believe that the exclusion of Dr. Sob-chuk’s opinion testimony,7 in the context of this trial, was fundamentally unfair and requires that the judgment be vacated and a new trial be granted.
. The trial court reasoned that Dr. Sobchuk’s testimony went to the "ultimate issue,” that Rules 403 and 704 together gave him discretion whether to admit such testimony, and that "this borders so closely upon the testimony on the ultimate issue as to the credibility of Calvin Woodburn, Jr., that the testimony of Doctor Sobchuk is excluded.”
. Maine’s final version followed the approach in the Federal Rules taken by the original House Bill, which eliminated opinion testimony from the United States Supreme Court’s proposed version. Subsequently, however, admissibility of opinion testimony was reinstated on the floor of the House and approved by the Conference ’ Committee and thus reappeared in the Federal Rules. 2 J. Moore, Moore’s Federal Practice, § 405.2 at 109 (Rules Pamph.1989).
.We have had previous difficulty with the wholesale exclusion of opinion testimony. In State v. Willoughby, 507 A.2d 1060 (Me.1986), we avoided the exclusion by distinguishing "a generalized description of [the defendant's] disposition in respect to a general trait, such as honesty" (inadmissible) from "medical testimony concerning a 'puffing syndrome,' which ... 'cannot fairly be called "character evidence" within the meaning of the rule’” (admissible) although the latter went directly to credibility. Id. at 1063-64. The commentators have been unable to square the decision with Rules 404 and 608. Field & Murray, Maine Evidence § 404.1 at 108 (1987).
. Calvin also answered questions on voir dire when he had no way to know the truth (color of the cross-examining lawyer’s undershirt and socks and what he had in his hand).
. I recognize that some authors and courts have rejected expert testimony on credibility issues because of their surmise that it will overwhelm or invade the province of the jury. E.g., Myers, The Child Witness: Techniques for Direct Examination, Cross-Examination, and Impeachment, 18 Pac.LJ. 801, 842-48 (1987), and cases cited therein. That factor may have partly influenced the trial court here, see note 1 supra. I am unpersuaded by the generalized fear that properly instructed juries cannot responsibly assess *349psychiatric or psychological testimony on credibility. Unlike our pre-Rules case of State v. Lewisohn, 379 A.2d 1192, 1203-04 (Me.1977), Dr. Sobchuk’s testimony was specifically not offered on whether Calvin, Jr. was testifying accurately at trial. There was thus no threat to the jury’s role in determining whether Calvin, Jr. was actually telling the truth on the witness stand.
. Accord, 7 Wigmore, Evidence § 1986 p. 244 (1978) (footnote omitted):
The Anglo-American rules of evidence have occasionally taken some curious twistings in the course of their development; but they have never done anything so curious in the way of shutting out evidential light as when they decided to exclude the person who knows as much as humanly can be known about the character of another, and have still admitted the secondhand, irresponsible product of multiplied guesses and gossip which we term "reputation."
. The specific incidents on which the opinion was based would be admissible only on cross-examination. M.R.Evid. 608(b).