Opinion of the Court
COX, Chief Judge:A general court-martial comprised of members convicted appellant, contrary to his pleas, of a single specification of wrongfully using marijuana, in violation of Article 112a, Uniform Code of Military Justice, 10 USC § 912a. Sitting at Hanscom Air Force Base, Massáchusetts, the court-martial sentenced appellant to dismissal from the service. The convening authority approved the sentence, and the Court of Criminal Appeals affirmed in an unpublished opinion.
The issue in this case is whether the military judge erred in redacting certain passages from a group of letters introduced on the merits by the defense to support appellant’s character.1 The redacted passages are these:
Defense Exhibit (D.E.) R: In all my experiences with Kurt Schelkle, I’ve never known him to use or be in any way involved with marijuana or illegal drugs.
*111D.E. S: I have never known Major Sehel-kle to use illegal drugs; in fact, I haven’t even known him to excessively use alcohol. D.E. T: I have never observed or known any-thing that would have led me to believe that Major Schelkle was using or involved with any illegal substances.
D.E. U: Over the years I have never known Kurt to use marijuana or any other illegal substance. On the social occasions that we’ve been together, he has never over-indulged in alcohol. He would usually have only two or three beers over the course of the evening. He has been very moderate in the use of alcohol.
D.E. V: In all my contact with Major Schelkle, I have never known him to use or be involved in any illegal drugs. Whenever I’ve been in Kurt’s company, I have never known him to even misuse alcohol. D.E. W: I have never known Major Schel-kle to use or be involved in illegal drugs.
Defense counsel agreed that the references to alcohol were irrelevant to this proceeding.
Although appellant was convicted largely on the basis of a random urinalysis, a major trial dynamic — injected preemptively into the proceedings by the defense — centered around evidence of appellant’s consciousness of guilt, in particular his failure, for some 5 months, to mention the accusation against him to his wife. See 1 C. Mueller & L. Kirkpatrick, Federal Evidence § 85 at 420 (2d ed.1994); 1A Wigmore, Evidence § 173 at 1840 (Tillers rev.1983). She ultimately learned of the charges from someone else, incidentally, on the eve of trial. Appellant’s explanation for his secrecy apparently provided the court members a significant opportunity to evaluate his credibility.
The defense also called four character witnesses on the merits. Two of them were coworkers of appellant who were with him daily. Both praised appellant’s character and work, and neither had observed him using drugs during the relevant period or sensed anything unusual about him. The third witness, a former supervisor of appellant, described his duty performance as “fantastic” and stated that he never saw appellant use drugs or behave unusually. The remaining character witness was appellant’s neighbor. He socialized extensively with appellant, saw him “almost every day,” believed him to be truthful, and never saw him use marijuana or act unusually during the relevant time period.
In lieu of seeking production of still more character witnesses on the merits, the defense proffered the six letters previously mentioned, which attested to appellant’s good military character. Trial counsel did not object to receipt of the letters in general or to character evidence per se, but he did object to the specific passages set out above.2 Counsel argued that these were not assertions of opinion or reputation of character, as permitted by Mil. R. Evid. 404(a)(1) and 405(a), Manual for Courts-Martial, United States (1994 ed.), but of specific instances of conduct (or nonconduct), as precluded by Mil. R. Evid. 405(a).
Defense counsel never contended that these assertions constituted opinion or reputation evidence so as to be admissible under Mil. R. Evid. 405(a). Instead, he argued that the challenged passages were admissible under Mil. R. Evid. 405(b), as evidence of a character trait that is an essential element of a defense, to wit: “good military character.” Thus, he argued that “specific instances of the person’s conduct” were indeed admissible.
The military judge, however, “d[id] not read 405(b) the same way that the defense d[id] in this regard.” 3 Neither do we.
*112The pertinent language from the Military Rules of Evidence is as follows:
Rule 404. Character evidence not admissible to prove conduct; exceptions; other crimes
(a) Character evidence generally. Evidence of a person’s character or a trait of a person’s character is not admissible for the purpose of proving that the person acted in conformity therewith on a particular occasion, except:
(1) Character of the accused. Evidence of a pertinent trait of the character of the accused offered by an accused, or by the piosecution to rebut the same.
* * *
(b) Other crimes, wrongs, or acts. Evidence of other crimes, wrongs or acts is not admissible to prove the character of a person in order to show that the person acted in conformity therewith. It may, however, be admissible for other purposes, such as proof of motive, opportunity, intent, preparation, plan, knowledge, identity, or absence of mistake or accident.
Rule 405. Methods of proving character
(a) Reputation or opinion. In all cases in which evidence of character or a trait of character of a person is admissible, proof may be made by testimony as to reputation or by testimony in the form of an opinion. On cross-examination, inquiry is allowable into relevant specific instances of conduct.
(b) Speciftc instances of conduct. In cases in which character or a trait of character of a person is an essential element of an offense or defense, proof may also be made of specific instances of the person’s conduct.
(Emphasis added.)
Our standard of review of a military judge’s ruling admitting or excluding evidence is abuse of discretion. United States v. Sullivan, 42 MJ 360, 363 (1995). Plainly, the military judge did not abuse that discretion here, as appellant’s contention that his character was an “essential element” of a defense is erroneous. Good military character, law-abidingness, and the like can be “defenses” in the sense that they may tend to negate an element of an offense, such as mens rea. They may also tend to cast doubt on the identity element of an offense, ie., that it was the accused who committed the offense. Such evidence is not, however, the sort having elements themselves, such as an “affirmative defense.” See United States v. Berri, 33 MJ 337, 343 (CMA 1991). Thus, the failure to observe criminal activity, or the observation of general good conduct, is not probative of an “essential element of a[ ] ... defense.” Mil. R. Evid. 405(b); see also S. Saltzburg, L. Schinasi, & D. Schlueter, Military Rules of Evidence Manual 497 (3d ed.1991), wherein it is suggested:
Character might be an element of a defense if entrapment is claimed and the government wants to prove predisposition. Specific acts might be used in this context.
The operation of Mil. R. Evid. 404 and 405, as pertains to this case, is quite plain. As all parties to the trial agreed, evidence of a pertinent trait of appellant’s character offered by the defense, including good military character and law-abidingness, is admissible. Mil. R. Evid. 404(a)(1). However, the form that evidence could take was limited to reputation and opinion testimony, and the military judge fully permitted all reputation and opinion evidence here. Mil. R. Evid. 405(a). As the defense has implicitly conceded throughout, a mere assertion of nonobservation of criminal conduct does not equate to reputation or opinion evidence. See United States v. Scarpa, 897 F.2d 63, 70 (2d Cir.1990); Fed.R.Evid. 405, 28 USC, Notes of Advisory Committee on Proposed Rules; 1 S. Saltzburg, M. Martin, D. Capra, Federal Rules of Evidence Manual 446-66 (6th ed.1994); see also Michelson v. United States, 335 U.S. 469, 69 S.Ct. 213, 93 L.Ed. 168 (1948); United States v. Midkiff, 15 MJ 1043,1051 (NMCMR 1983); United States v. Giles, 13 MJ 669, 671 (AFCMR 1982).
In the instant case, moreover, the military judge expressly ruled that the live witnesses could be asked about appellant’s conduct during the charged period, and the witnesses so testified. Furthermore, it can be fairly assumed that the senior panel of military officers would have well realized that none of *113the many servicemembers who came forward to present evidence on behalf of appellant, either in the form of live testimony or written letter, would have held a high opinion of appellant’s character or performance if they had ever observed him using drugs or acting suspiciously in that regard. Thus, in reality, the type of information appellant sought to place before the members was abundantly evident.
Additionally, no evidence was presented, express or implied, regarding any other instances of criminal activity or misconduct by appellant, either within or without the charged period.4 Lastly, the excluded evidence was cumulative and at best marginally relevant. See United States v. Hill, 40 F.3d 164 (7th Cir.l994)(defendant’s failure to steal three “test letters” was “only tangentially relevant” to whether she intended to embezzle check 5 months earlier).
The decision of the United States Air Force Court of Criminal Appeals is affirmed.
Judges CRAWFORD and GIERKE concur.
. We granted this issue for review:
WHETHER THE MILITARY JUDGE ERRED, TO THE PREJUDICE OF APPELLANT, BY EXCLUDING EVIDENCE FROM DEFENSE WITNESS STATEMENTS IN WHICH EACH SAID THEY HAD NEVER SEEN OR KNOWN APPELLANT TO HAVE USED DRUGS.
. This matter should have been resolved under RCM 811, Manual for Courts-Martial, United States (1995 ed.), regarding stipulations of expected testimony, rather than as an evidentiary matter. All six statements were inadmissible hearsay absent government agreement. Mil. R.Evid. 801, Manual, supra.
. The military judge further analogized the situation to a drunk-driving case. The fact that a witness had not seen an accused drive drunk in the past did not seem, to the judge, to go to the accused’s character. Thus, although the judge redacted the assertions that appellant had not been observed using drugs, he received the balance of those parts of the statements that went to character.
. Appellant now complains that the prosecution, through its drug expert, implied that appellant may have used drugs prior to the charged period, and thus the defense should have been allowed to present the evidence of nonobservation of prior drug use. Those portions of the drug expert’s testimony in question, however, were part of a series of questions about the general characteristics of marijuana usage vis-a-vis the persistence of the tetrahydrocannabinol metabolite in urine. For example, the expert was asked:
Assuming for hypothetical purposes that the accused used marijuana on a regular basis and stopped bn the 29th of March 1993. Could the result in this test be consistent with such behavior?
The expert agreed that it was possible. The defense did not object to this testimony, and, in the context in which it was given, it cannot possibly be construed as evidence or innuendo that the expert was of the opinion or had a basis for believing that appellant previously used drugs.