Whether or not intoxication can be used as a valid defense in a criminal trial often will depend on whether the defendant was involuntarily intoxicated or voluntarily intoxicated at the time that he committed the crime.
Intoxication is considered involuntary if the defendant either did not know that the substance he consumed was intoxicating or if he consumed the intoxicating substance under duress or coercion. In addition, the Model Penal Code also considers "pathological intoxication" to be involuntary. Intoxication is pathological, according to the Model Penal Code, if the defendant consumes a small amount of an intoxicating substance yet suffers a disproportionately severe reaction to which he did not know that he was susceptible to. So, for example, if a person consumes a small amount of liquor and, because of an allergy that he does not know about, suffers a severe reaction that renders him much more intoxicated than an ordinary person would be under the circumstances, this person is in a state of pathological intoxication.
Involuntary intoxication is a complete defense to all crimes if the intoxication placed the defendant in a state of mind that would qualify him as legally insane. In other words if the defendant became involuntarily intoxicated and the intoxication caused him to either not understand that his actions were wrong or deprived him of his ability to refrain from committing his criminal act, he can use his involuntary intoxication to obtain an acquittal for the crime he is charged with. See People v. Penman, 110 N.E. 894 (Ill. 1915). For example:
1) Flounder, a freshman at Faber College, has decided to join the Delta fraternity. After a night of partying with his newfound frat brothers, Flounder is exhausted and he is afraid that he will sleep through his first day of classes. Otter, one of Flounder’s friends, gives him a little blue pill and tells him that it is a sugar pill that will give him energy to stay awake through class. The pill is actually a very strong amphetamine. Not knowing what the pill really is, Flounder takes it and, within a half an hour, is highly intoxicated. While he is in his intoxicated state, Flounder robs Dean Wermer’s house. If Flounder can successfully prove that his involuntary intoxication put him in a mental state in which he did not know that what he was doing was wrong, he cannot be convicted of robbing the house.
2) Flounder, a freshman at Faber College, decides to join the Delta fraternity. On his first night at the university he attends a Delta party. Upon entering the Delta fraternity house, Otter hands Flounder a small shot glass full of gin. Flounder has never had gin and is unaware that he has a very rare allergy to juniper berries which is the main ingredient in gin. Flounder takes a sip of his drink and, within five minutes, becomes heavily intoxicated. While he is in his intoxicated state, Flounder robs Dean Wermer’s house. If Flounder can successfully show that he was not aware that gin would put him in such a state of intoxication and that his involuntary intoxication put him in a mental state in which he did not know that what he was doing was wrong, he will not be convicted of robbing the house.
A defendant who suffers from a physical impairment due to prolonged voluntary intoxication may use that impairment as the basis for a defense if the impairment qualifies as legal insanity. For example:
Flounder is a chronic alcoholic and has been one ever since his freshman year at Faber College thirty years ago. As a result of his many years of alcohol abuse, Flounder frequently blacks out for several hours at a time and, during these periods of black out, is unable to distinguish between right and wrong. During a recent black out, Flounder robs Hoover’s Wines and Spirits, a liquor store around the corner from Flounder’s house. If Flounder can demonstrate that his mental impairment rendered him unable to recognize right from wrong during the period in which he was blacked out, Flounder will be able to avoid a conviction for robbery even though the mental impairment was brought on by years of voluntary intoxication.
Voluntary intoxication is never a defense that can be mounted independently of the elements of the crime that the defendant has been charged with. In other words, unlike insanity and involuntary intoxication, which can be mounted as a defense to any crime and does not have to negate specific elements of the particular crime charged, voluntary intoxication cannot be used as a defense to any crime. However, it can be used to negate the intent required to commit a crime. Thus, most jurisdictions allow a defendant to use voluntary intoxication as a defense to specific intent crimes only. Therefore if the defendant is charged with a general intent crime, he cannot use voluntary intoxication as a defense at all. See People v. Hood, 1 Cal. 3d 444 (1969). For example:
One night after a particularly nasty fight with Wilma, Fred goes to a local tavern and drinks a whole bottle of Jack Daniels. On his way back home, Fred breaks into Barney's house and rapes Barney’s wife, Betty. Fred is charged with burglary and rape. During the trial, Fred argues that he was so intoxicated when he broke into Barney’s house that he had no idea what he was doing. Since Fred’s intoxication was voluntary, he might be able to win an acquittal for the burglary since burglary is a specific intent crime. However, he will not be able to use his voluntary intoxication as a defense to the rape, because rape is a general intent crime.
Please note that the jurisdictions that allow voluntary intoxication as a defense to specific intent crimes make this an affirmative defense. Therefore, the burden of proof is on the defendant to prove that he was so intoxicated that he did not have the requisite intent necessary to be convicted.
There are jurisdictions who do not make this distinction between specific and general intent crimes on both sides of the spectrum. A few jurisdictions do not allow voluntary intoxication to be used as a defense to any crime, even specific intent crimes, while some other jurisdictions allow voluntary intoxication to be used as a defense to any crime, including general intent crimes. See Terry v. State, 465 N.E.2d 1085 (Ind. 1984).
The Model Penal Code, which defines criminal mental states in terms of purpose, knowledge, recklessness or negligence, allows a defendant to use voluntary intoxication as a defense to crimes requiring proof of a state of mind of either purpose or knowledge. In other words, if a defendant is on trial for committing a crime but he can only be convicted of the crime if he committed it either willingly or knowingly, the defendant will be acquitted if he can show that he committed the crime while voluntarily intoxicated. In these instances, the Model Penal Code will allow a defendant to use his voluntary intoxication as a valid defense. However, if the defendant is on trial for a crime for which he can be convicted if he committed it recklessly or negligently (as is the case with most crimes, under the Model Penal Code), then he will not be able to use voluntary intoxication as a defense.
Finally, please note that in situations where intoxication is an element to the crime itself, such as public intoxication or drunk driving, voluntary intoxication will obviously not be available as a defense. See Shelburne v. State, 446 P.2d 56 (Okla. 1968). However, under these circumstances, a defendant can successfully raise a defense of involuntary intoxication.