(dissenting):
The appellant was convicted by a general court-martial with members of felony murder, robbery (two specifications), conspiracy to commit robbery, aggravated assault, and absence without leave, in violation of Articles 118(4), 122, 81, 128, and 86, Uniform Code of Military Justice, 10 U.S.C. §§ 918(4), 922, 881, 928, and 886, respectively. He was sentenced to a dishonorable discharge, confinement at hard labor for life, and forfeiture of all pay and allowances. The convening authority reduced the period of confinement, to 25 years, but in all other respects he approved the findings and the sentence. His action was affirmed by the United States Army Court of Military Review. 2 M.J. 799 (1976).
During the trial, the appellant contested his legal responsibility for the charged offenses on the basis that he was, at the time of their alleged commission, legally insane. Four psychiatrists testified on this issue. Dr. Martin Blinder, a witness for the defense, testified at substantial length about the appellant’s emotional and psychological makeup and about the appellant’s background leading to this makeup. He concluded that the appellant was “psychologically defective” and that he did “not see him [the appellant] equal to the mental processes necessary to conform his behavior to the requirements of the law.” When the appellant’s attorney read to Dr. Blinder a legal definition of “mental defect,” the witness responded that that was what he meant when he said the appellant suffered from a mental defect.1 Further, Dr. Blind*22er opined that it would be “very difficult” for the appellant to adhere to the right under conditions where there is “peer pressure from certain kinds of charismatic positions.” 2 He explained that he did not mean that the appellant could not adhere to the right; only “that his ability to adhere to the right in certain well-defined circumstances . is grossly impaired.” Dr. Blinder repeated this conclusion of gross impairment several times during his testimony.
The prosecution countered with three psychiatrists — Dr. Dale Howard, Dr. Noni-hal Chaudhri, and Dr. Elliot Cooperman. The testimony of these three doctors differed somewhat from that of Dr. Blinder, and among each other as well. Dr. Howard indicated that he diagnosed the appellant as an “antisocial personality” who had no mental defect and no impairment in his ability to adhere to the right. Next, Dr. Chaudhri stated that he, too, believed the appellant to be an “antisocial personality” and that he did not believe the appellant suffered from any mental defect, though he conceded that another psychiatrist could conclude that the appellant did suffer from such a malady. Additionally, he concluded that the appellant’s ability to adhere to the right was “mildly impaired.” Finally, Dr. Cooperman agreed that the appellant was an “antisocial personality” but asserted that the appellant was suffering from a mental defect and that his ability to adhere to the right was mildly impaired as a result.
To guide the court members in applying this testimony to the concept of the appellant’s mental responsibility, the trial judge delivered the following instruction, inter alia:
A person is not mentally responsible, in a criminal sense, for an offense unless he was, at the time of the offense, so far free from mental defect, disease, or derangement as to be able concerning the particular act or acts charged both to distinguish right from wrong and to adhere to the right. The phrase “mental defect, disease or derangement” comprehends those irrational states of mind which are the result of deterioration, destruction, or malfunction of the mental, as distinguished from the moral faculties. To constitute lack of mental responsibility, the impairment must not only be the result of mental defect, disease or derangement but must also completely deprive the accused of his ability to distinguish right from wrong or to adhere to the right as to the acts charged.
This standard for mental responsibility is commonly referred to as the M’Naghten3 standard with the addition of the irresistible impulse test. That standard, and the judge’s instructions, reflected the law of insanity as it existed in the military at the time of the appellant’s trial.4 However, in United States v. Frederick, 3 M.J. 230 (C.M.A.1977), this Court rejected that standard in favor of the more enlightened definition of insanity recommended by the American Law Institute (ALI):5
*23(1) A person is not responsible for criminal conduct if at the time of such conduct as a result of mental disease or defect he lacks substantial capacity either to appreciate the criminality of his conduct or to conform his' conduct to the requirements of law.
(2) As used in this Article, the terms “mental disease or defect” do not include an abnormality manifested only by repeated criminal or otherwise antisocial conduct.
As may readily be seen, the primary difference between the two standards, as relevant to this case, is the degree of the incapacity to adhere to the right. While the former test and the judge’s instructions require that the defect “completely deprive” the appellant of such capacity, the newly adopted one requires only that the defect deprive the appellant of the “substantial capacity” to do so in order legally to be insane and not criminally responsible for his misconduct.
This difference requires that we examine the present record “to determine if there is a fair risk of prejudice to the appellant from the use of the rejected standard of mental responsibility.” United States v. Frederick, supra at 238.6 While there was conflicting testimony at the appellant’s trial regarding whether the appellant was afflicted with a mental defect, there was no testimony that such a defect, if one existed, completely deprived the appellant of the ability to adhere to the right, as opposed to substantially doing so. We do not know why the court members rejected the appellant’s insanity defense, only that it did so. It may have been because it concluded that there was no mental defect, but it is just as plausible that it was because of the total absence of any evidence that the defect completely deprived the appellant of the ability to adhere to the right.. If it was the latter, then consideration of the testimony as summarized earlier in this opinion in light of the newly adopted standard might well have led to a different conclusion.7 Under these circumstances, I determine that the appellant was prejudiced.
I would reverse the decision of the United States Army Court of Military Review, set aside the findings and the sentence, and authorize a rehearing.8
Judge Matthew J. Perry took final action in this case prior to his resignation as a judge of this Court pursuant to his appointment and confirmation as a United States District Judge for the District of South Carolina.
. Q [by defense counsel] Then right here, one thing further because we always have a little difficulty between the legal and medical field, but for-our purposes in the law here we have the following definition, (reading): “The *22phrase ‘mental defect, disease, or derangement’ comprehends those irrational states of mind which are the result of deterioration, destruction, or malfunction of the mental faculties.” In your use of mental defect, do you mean it to be within that definition?
A Yes.
The defense counsel, of course, was reading from paragraph 120b, Manual for Courts-Martial, United States, 1969 [Revised edition).
. The violent crimes at issue were allegedly committed along with another soldier who, apparently, at the completion of one of the robberies took the weapon used in the robbery from the appellant because the latter could not fire it as the former had directed, and fired repeated rounds into their robbery victims as the appellant and his cohort fled in an automobile. Dr. Blinder testified that the appellant’s difficulty in adhering to the right arose either in the absence of a “good” model for him to follow or in the presence of a particularly charismatic “bad” model. Specifically, the defense position at trial was that the other soldier’s personality compellingly overwhelmed the appellant’s ability to adhere to the right at the time of the commission of the offenses charged.
. M’Naghten’s Case, 10 Cl. & F. 200, 8 Eng. Rep. 718 (H.L.1843).
. See para. 120b, Manual, supra.
. Model Penal Code § 4.01, Proposed Official Draft (May 4, 1962).
. The ALI standard is to be applied to all cases pending appeal at the time of the Frederick decision and to all cases tried subsequent to the date of that decision.
. This is the key to the resolution of this case. Judge Cook concludes that “[i]n returning a verdict of guilty, the court members obviously did not accept Dr. Blinder’s opinion as to the degree of accused’s inability to adhere to the right.” In fact, it means no such thing for, in point of law, no testimony — including Dr. Blinder’s — suggested a total inability to adhere to the right. In other words, if Dr. Blinder had been believed, under the standard applied by the members, the conclusion still was inescapable that the appellant was mentally responsible; on the other hand, again assuming acceptance of Dr. Blinder’s testimony, under the new standard, a finding of irresponsibility might well have obtained. And that is the crux: there is a fair risk that under the new standard, there may have been different result.
. Though I disassociate myself from that portion of the lead opinion treating the issue, I join in rejecting the appellant’s claim that he was denied a speedy trial, concluding that the presumption of such a denial, which arose by the passage of more than 90 days between the date when appellant was placed in pretrial confinement and the date trial began, United States v. Burton, 21 U.S.C.M.A. 112, 44 C.M.R. 166 (1971), is rebutted in the record. Additionally, I assume that at a rehearing the defense again would litigate the voluntariness of the appellant’s extrajudicial confessions and that the judge properly would tailor his instructions on that issue to include as a factor for the court’s consideration the appellant’s mental condition at the time of the interrogation; therefore, I do not now address the appellant’s claims of error in these areas.