[1][2] Early English common law recognized "settled insanity" as a complete defense for a person who is a habitual drunk but is not intoxicated at the time of the offense.
Traditionally, under English common law intoxication, no matter to what degree, was not considered grounds for excusing the defendant's criminal behavior.
However, over the last half century, there has been a movement toward allowing intoxication as evidence admissible in court to help the jury understand the criminal act and perhaps use it as an excuse or a mitigating factor.
Similarly, the plea of temporary insanity (applicable only to charges of murder) can serve to reduce the charges from first degree murder to assault or lessen the sentence if it can be shown that the defendant, due to intoxication, acted without deliberation or reflection (lacking malice aforethought), thus negating specific intent.
[5] Some jurisdictions allow voluntary intoxication in the context of a preexisting mental disorder to qualify for an insanity defense.
At the time of the offenses, Herbin was a long-term guest of the victim's parents and was on crutches due to a gunshot wound received when he tried to enter his mother's house while on crack cocaine a week before.
[7] At trial, Herbin testified that he felt disturbed that day and had no memory of what happened except seeing the victim sitting in a pool of blood.
[7] On the other hand, Herbin called paramedics and properly recited the address, which had many numbers, and his voice on the 911 tape was controlled and calm.
In order to qualify for this defense, Herbin was required to provide substantial evidence of the presence of a mental disorder and the connection between it and the substance abuse.
In Herbin, the court found that The weight of authority in this country recognizes an insanity defense that is based on a mental disease or defect produced by long-term substance abuse."
At the same time, "evidence of mere narcotics addiction, standing alone and without other physiological or psychological involvement, raises no issue of such a mental defect or disease as can serve as a basis for the insanity defense."
The court held that the substance abuse did not serve as evidence for a "settled insanity" defense alone without the link to a mental disorder.
Also, although Herbin did provide an extensive history of drug and sexual abuse, the court said no evidence showed either of these issues were causes or results of a mental disorder.
[2] Aggressiveness, memory lapses and other common symptoms resulting from acute intoxication are not sufficient in themselves to excuse criminal acts.
Further, not all psychotic reactions caused by substance abuse result in behavior that can be related to the criminal act in a way that can support an insanity defense.