Whether the trial court erred by refusing to instruct the jury on insanity.
Holding
No. Cooper's evidence did not overcome the presumption of sanity or generate a reasonable doubt about his legal sanity because his temporary psychosis resulted from voluntary drug use.
Reasoning
Arizona presumes every criminal defendant sane. A defendant must first offer sufficient evidence to generate a doubt about sanity before the issue goes to the jury and the State must prove sanity beyond a reasonable doubt. Arizona applies the M'Naghten test: insanity requires that, at the time of the act, the defendant did not understand the nature and quality of the act or did not know that it was wrong.
Cooper's psychiatrist and psychologist did testify that he met the M'Naghten description at the time of the charged conduct. But both experts also agreed that he would have been sane without his drug use. They described his condition as a "toxic psychosis" or an "acute drug induced psychotic episode," tying the claimed incapacity directly to amphetamines Cooper had voluntarily taken for several days.
The law distinguishes an existing mental illness from a temporary incapacity caused by voluntary intoxication. Insanity may remain available when a genuine, settled mental illness exists, even if prolonged alcohol or drug use helped cause it. But a short-lived mental disturbance produced by voluntarily consuming alcohol or drugs is not legal insanity. The same rule applies to drug intoxication as to alcohol intoxication.
Because Cooper was sane before taking the amphetamines and his bizarre conduct resulted from an artificially induced condition brought about by his own voluntary choice, his drug-induced psychosis did not furnish a legal excuse. Voluntary intoxication could be considered only on the question of specific intent, and the trial court properly gave an instruction on that limited effect. Thus, the evidence did not require an insanity instruction.