(concurring in the result):
OVERVIEW
Appellant contends that an erroneous evidentiary ruling by the military judge violated his constitutional right to present his defense at this court-martial. The majority holds that defense-proffered evidence was properly excluded by the military judge under various military rules of evidence and that no infringement of appellant’s constitutional right to present his defense occurred. The dissent asserts that both evidentiary and constitutional error occurred in this case. I agree with the dissent that the military judge’s relevance ruling was erroneous, but I conclude that it did not materially prejudice appellant or amount to constitutional error.
The CourG-Martial
Appellant was found guilty of assault with a means likely to produce grievous bodily harm on his 4-week-old son, Jarod; the prosecution’s case, however, was based only on circumstantial evidence. There were no eyewitnesses to the crime and only appellant and his wife had significant access to the baby that night.
At issue on this appeal is the correctness of the judge’s decision excluding certain defense evidence which appellant argues circumstantially showed an alternate perpetrator of the charged offense, i.e., his wife, Nicole Dimberio. Appellant had offered expert testimony from a psychiatrist, Doctor Sharbo, that appellant’s wife had a personality disorder including traits of impulsivity and the inability to handle stress well. He asserted that this expert testimony was relevant in light of Doctor Wacksman’s expert testimony, previously admitted, that shaken-baby injuries such as baby Jarod’s are usually caused by impulsive acts of a caregiver under stress. (R. 276-77)
More particularly, defense counsel at trial offered expert testimony from Doctor Sharbo as to Mrs. Dimberio’s character disorders of impulsivity and inability to handle stress.1 He did so for three reasons:
First, to show her character and draw an inference therefrom and from other evidence in this case that she did the charged act (R. 498)2; second, to show that appellant did not act intentionally if he did the charged act3 *29(R. 501); third, to show Mrs. Dimberio’s state of mind, a circumstantial fact identifying her as the actual perpetrator of the charged offense (R. 502). The military judge ruled that the evidence was irrelevant because there was no showing of nexus between Mrs. Dimberio’s character disorders and the acts of violence charged in this case. (R. 501, 503)
Erroneous Relevancy Ruling
In my view, the military judge clearly erred when he concluded that the defense-proffered expert testimony was not relevant to a material issue at appellant’s court-martial. See Mil.R.Evid. 401 and 402. The third reason for which the defense offered expert testimony in this case was that appellant’s wife had certain character disorders (instability and inability to handle stress) and therefore she was probably stressed out on the night that baby Jarod was assaulted. It further offered this evidence of Mrs. Dimberio’s mental state on the night in question to establish a fact identifying her, not appellant, as the assailant of baby Jarod. See generally 3 Jones on Evidence-Civil and Criminal § 17:39 (7th ed.1998) (distinguishing between identity evidence and evidence offered to show conduct). This was a viable evidentiary theory and purpose in appellant’s case. See 2 Wigmore, Evidence §§ 411-13 (Chadbourn rev.1979); see also United States v. St. Jean, 45 MJ 435, 444 (1996); United States v. Combs, 39 MJ 288,291 (CMA 1994).
Moreover, there was evidence linking Mrs. Dimberio’s character disorders to that particular mental state, and linking that mental state to a violent assault. Doctor Wacksman, a government witness, testified on direct examination that the injuries inflicted on Jarod were consistent with an intentional assault or shaken baby syndrome. He further agreed on cross-examination by the defense that shaken baby syndrome was an unpremeditated event related to stress and resulted from “an acute abrupt momentary loss of control by the caregiver.” (R. 277) Clearly, this expert testimony established the necessary scientific nexus between the proffered defense evidence and the charged offense, and it went beyond mere speculation. Cf. United States v. Han, 230 F.3d 560, 563 (2d Cir. 2000); see State v. Miller, 709 P.2d 350, 353 (Utah 1985); see generally State v. Oliviera, 534 A.2d 867 (R.I.1987). In my view, this evidence was relevant to show the identity of an alternate perpetrator of the charged offense (one of the classic defenses to any crime). Cf. United States v. Powers, 59 F.3d 1460, 1471-73 (4th Cir.1995) (no “valid scientific connection” established between a particular criminal offense and evidence that appellant does not fit profile of one who could commit that offense).4
Prejudice
Nevertheless, other evidence showing Mrs. Dimberio’s stressed-out mental state on the night in question was admitted in this case. It could also serve as a basis to identify her as the perpetrator of the charged offense and permit appellant to present his alternate-perpetrator defense to the members. (R. 600, 604-05) In these circumstances, I conclude that the military judge’s erroneous evidentiary ruling did not materially prejudice appellant’s rights or amount to constitutional error. See generally Fortini v. Murphy, 257 F.3d 39, 47-48 (1st Cir.2001) (erroneous exclusion of defense evidence under circumstances did “not rise to the level of a Chambers[5] violation”); Romano v. Gibson, 239 F.3d 1156, 1166-68 (10th Cir.2001) (no constitutional error where only incremental evidence of alternate perpetrator improperly excluded); People of Territory of Guam v. *30Ignacio, 10 F.3d 608, 615 (9th Cir.1993) (excluded defense evidence not substantial).
On this point, I again emphasize that defense counsel argued, inter alia, that the proffered defense-expert evidence was relevant to show Mrs. Dimberio’s stressed state of mind on the night of the alleged assault of her baby. He then argued that her stressed state of mind, among other facts, identified her, not appellant, as the assailant of baby Jarod. However, Doctor Garman, a witness for the defense, also testified that Mrs. Dimberio told him the morning after the assault that she was stressed the night before. (R. 485, 491, 494). Direct evidence of this state of mind in the form of an admission by Mrs. Dimberio was certainly stronger than the circumstantial showing of this same state of mind, based on her character disorders, which was prohibited by the judge. Moreover, defense counsel was free to argue and did argue that this was “a crime ____ of stress” and Mrs. Dimberio was a stressed out person on the night in question. (R. 604-05)
In reaching the above conclusions I have relied heavily on my reading of the record of trial and my understanding of the positions of the parties at this court-martial. In my view, the prosecution relied most heavily on appellant’s pretrial admissions to possibly injuring the child by accident. It was the defense, in an attempt to focus suspicion on Mrs. Dimberio as the actual assailant, who first played the psychological-character card during pre-trial motions and in the opening argument of the trial. (R. 26-30, 48-50, 51-53, 96-98, 100). In sum, appellant was entitled to a fair trial, not a perfect trial, and that is exactly what he received in this case.
. Mil.R.Evid. 405, Manual for Courts-Martial, United States, 1984, provides for proof of character by means of opinion testimony without distinguishing between lay and expert testimony. See 2 Weinstein, Federal Evidence § 405.04[2][a]. Moreover, federal courts and most state courts consider expert-opinion testimony on personality traits as character evidence within the meaning of this rule. See 2 Weinstein, Federal Evidence § 405.04[2][cj; 3 Jones on Evidence-Civil and Criminal § 16:24 (7th ed.1998). See also United States v. Nunn, 940 F.2d 1148, 1149 (8th Cir. 1991); United States v. Roberts, 887 F.2d 534, 536 (5th Cir.1989); State v. Shuck, 953 S.W.2d 662 (Tenn.1997); People v. Stoll, 49 Cal.3d 1136, 265 Cal.Rptr. 111, 783 P.2d 698 (1989). But see State v. Ambrosia, 67 Ohio App.3d 552, 587 N.E.2d 892, 899 (1990); State v. Conlogue, 474 A.2d 167, 172 (Me.1984); see generally State v. Hulbert, 481 N.W.2d 329, 333-34 (Iowa 1992); Commonwealth v. Trowbridge, 36 Mass.App.Ct. 734, 636 N.E.2d 291, 295-96 (1994).
. With certain carefully-limited exceptions (for the accused, a victim, or a witness), evidence of a person’s character is not admissible to show a person acted in conformity with that character. See Mil.R.Evid. 404(a). It is black-letter law that a criminal accused may not introduce character evidence to show a third party committed the charged offense. See 1A Wigmore, Evidence § 68 (Tillers rev. 1983); 22 Wright and Graham, Federal Practice and Procedure: Evidence § 5236 at 385-86 (1978); but see State v. Anderson, 379 N.W.2d 70, 79 (Minn.1985). Accordingly, in my view, the defense-proffered evidence here was per se inadmissible for the purpose of showing Mrs. Dimberio acted in accordance with this character on the night in question. See generally S. Childress and M. Davis, 1 Federal Standards of Review § 4.03 at 4 — 29 (3d ed.1999).
. The challenged evidence showed Mrs. Dimberio’s character disorders and probable state of mind, not appellant's. Accordingly, it was clearly irrelevant to show that appellant did not act *29with the requisite criminal intent for conviction of aggravated assault.
. The majority asserts that the proffered defense evidence was inadmissible under Mil.R.Evid. 403 and 702. The military judge, however, ruled that the proffered defense evidence was not relevant; he did not do a balancing test or rule that the evidence was relevant but unfairly prejudicial under Mil.R.Evid. 403. Moreover, the majority’s conclusion under "Daubert" and "Houser,” 56 MJ at 27, ignores the scientific-nexus testimony of Doctor Wacksman and, in my view, conflicts with this Court’s decision in United. States v. St. Jean, 45 MJ 435, 444 (1996).
5. Chambers v. Mississippi, 410 U.S. 284, 93 S.Ct. 1038, 35 L.Ed.2d 297 (1973).