OPINION OF THE COURT
DeFORD, Judge:The appellant was convicted contrary to his pleas, of attempted murder and attempted robbery in violation of Article 80, Uniform Code of Military Justice (UCMJ), 10 U.S.C. § 880.
Our review of the appellant’s case is pursuant to Article 66, UCMJ, 10 U.S.C. § 866.
Appellant’s principal defense at trial was temporary insanity. A defense expert witness testified that the appellant suffered a psychosis which took the form of a dissociative reaction at the time of the alleged act. The expert witness further testified that he believed that the appellant could not adhere to the right.
The defense testimony was received and evaluated by the Court under the commonly described M’Naghton Standard of Insanity.1
During the pendency of appellant’s appeal, the United States Court of Military Appeals decided United States v. Frederick.2 In that opinion, the Court rejected the M’Naghton Standard in favor of the American Law Institute (ALI) definition of insanity.3 Further, that Court decreed that the ALI Standard on insanity would be applicable to all cases pending appeal on the date Frederick, supra, was released (25 July 1977).
Lastly, Frederick, supra, authorized an examination of the record to determine if there was a fair risk of prejudice to the appellant from the use of the rejected M’Naghton Standard.
*896Here, as in Frederick, there was considerable evidence that appellant could not adhere to the right. Under the circumstances, we conclude that the appellant was prejudiced.
The findings of guilty and the sentence are set aside. A rehearing may be ordered by the same or a different convening authority.
. See paragraph 120, Manual for Courts-Martial, United States, 1969 (Revised edition).
. 3 M.J. 230 (CMA 1977).
. See United States v. Frederick, supra at page 234.