Does case law applicable to an insanity defense have any relevance to the defense that the accused lacked the requisite mental state?

1 It is not clear that case law applicable to an insanity defense is relevant to the defense that the accused lacked the requisite mental state. "The use of expert testimony for [the purpose of negating mens rea] is entirely distinct from the use of such testimony to relieve a defendant of criminal responsibility based on the insanity defense or one of its variants, such as diminished capacity." United States v. Demma, 523 F.2d 981, 986 n. 14 (9th Cir.1975). We need not resolve this issue because we conclude that the government offered adequate evidence to discredit the psychiatric evidence.