In Stamper v. Commonwealth, 228 Va. 707, 324 S.E.2d 682 (1985), the defendant sought to "introduce psychiatric testimony to prove that he was manic-depressive, in a manic state on the date of the offense, and consequently incapable of forming the intent to distribute, which is a requisite element of the crime with which he was charged." 228 Va. at 715-16, 324 S.E.2d at 687. The Supreme Court held that in the absence of an insanity defense, the trial court properly excluded the evidence of Stamper's mental state at the time of the offense because it was irrelevant to the issue of guilt. See id. at 717, 324 S.E.2d at 688. Stamper did not present evidence that he was insane, but attempted to introduce psychiatric testimony that he was manic-depressive and in a depressive state on the date of the offense and, therefore, incapable of forming the requisite intent to distribute. The trial court refused to consider such evidence. Id. at 716, 324 S.E.2d at 687. The Supreme Court wrote: For the purposes of determining criminal responsibility a perpetrator is either legally insane or sane; there is no sliding scale of insanity. The shifting and subtle gradations of mental illness known to psychiatry are useful only in determining whether the borderline of insanity has been crossed. Unless an accused contends that he was beyond that borderline when he acted, his mental state is immaterial to the issue of specific intent. Accordingly, we hold that evidence of a criminal defendant's mental state at the time of the offense is, in the absence of an insanity defense, irrelevant to the issue of guilt. Id. at 717, 324 S.E.2d at 688.