Fundamentals of Criminal Law by Adam J. McKee

Intoxication, or the impairment caused by substances, can sometimes be invoked as a defense in legal cases. The ability of an individual to make rational choices can be compromised due to intoxication, and this can influence their culpability or responsibility for their actions. Let’s delve into how intoxication is viewed as a defense, the types of intoxication, and how the law sees these cases.

Definition of Intoxication

Intoxication refers to a disruption in one’s mental or physical capabilities due to substances entering the body. These substances can include alcohol, legal drugs, or illegal drugs. As the Model Penal Code puts it, intoxication is “a disturbance of mental or physical capacities resulting from the introduction of substances into the body.”

Voluntary vs. Involuntary Intoxication

There are two types of intoxication defenses: voluntary and involuntary. It’s important to note that while involuntary intoxication can be used as a defense, voluntary intoxication cannot.

  • Voluntary Intoxication: This occurs when a person knowingly introduces a substance into their body, understanding its intoxicating effects. Voluntary drunkenness is not accepted as a defense in legal contexts. In many cases, being voluntarily intoxicated can even escalate the severity of the offense.
  • Involuntary Intoxication: This can be a more robust defense. It happens when a person ingests drugs or alcohol unknowingly or when forced or tricked into doing so. The Model Penal Code draws a parallel between involuntary intoxication and “substantial capacity”, hinting that its core reasoning is similar to the insanity defense.

Distinctions and Implications

While both voluntary and involuntary intoxication can influence an individual’s capacity to form intent, the way courts perceive and handle these two types can differ drastically. Voluntary intoxication, resulting from an individual’s choice to consume an intoxicating substance, is generally not favored as a defense. This is mainly because the law expects individuals to foresee the potential consequences of their actions when they willingly consume such substances.

In contrast, involuntary intoxication, which occurs when an individual consumes an intoxicating substance without knowledge or through coercion, is more sympathetically viewed in courts. In these cases, the individual had no intention of becoming impaired, and their subsequent actions might be deemed out of character or beyond their usual control. Courts often liken the effects of involuntary intoxication to other defenses like insanity, acknowledging that the individual might not have had the requisite mens rea due to their unexpected altered state. However, it remains essential for the defense to provide compelling evidence of the involuntary nature of the intoxication for it to be a valid defense.

Insight from A.C.A. § 5-2-207 on Intoxication

The A.C.A. § 5-2-207 provides a clear stance on intoxication:

  • Section (a) states that non-self-induced intoxication can be an affirmative defense if, due to that intoxication, a person doesn’t have the capacity to realize their actions’ illegality or to act within the law.
  • Section (b) defines “intoxication” and “self-induced intoxication”. Specifically, it describes self-induced intoxication as a result of a known substance that the person willingly takes, knowing its intoxicating tendencies.

Relevance to Mens Rea and Recklessness

In legal proceedings, the concept of mens rea, which translates to the intent or knowledge of wrongdoing, plays a pivotal role in determining an individual’s culpability for a crime. When the mens rea of a crime is based on recklessness, or a blatant disregard for the potential consequences of one’s actions, the defense of voluntary intoxication becomes considerably weak. This is because choosing to consume a substance that impairs judgment, like alcohol or drugs, and then engaging in potentially harmful actions is viewed by the court as an amplification of that recklessness. Essentially, the act of becoming voluntarily intoxicated is seen as further evidence of the individual’s disregard for the safety and well-being of others. Therefore, instead of mitigating the severity of the crime or offering any form of excuse, voluntary intoxication often compounds the perception of recklessness and diminishes its viability as a defense strategy.

The Consequences of DUI Accidents

Driving under the influence (DUI) accidents, where alcohol or drugs impair a driver, are treated with severe gravity by the criminal justice system. When a person is harmed or injured due to a DUI accident, the intoxicated driver is typically faced with enhanced penalties, reflecting society’s condemnation of such reckless behavior. Beyond the standard DUI charges, which can already entail significant fines, license suspension, and potential jail time, causing bodily harm can lead to additional charges like vehicular assault or even vehicular manslaughter if the accident results in a fatality. Such incidents underscore the immense responsibility that individuals have when operating a vehicle, especially when under the influence. Society and the legal system view the combination of driving and intoxication as a profound betrayal of that responsibility, warranting stringent penalties to deter such actions and protect public safety.


While intoxication can influence one’s ability to make sound decisions, its acceptance as a defense varies. Involuntary intoxication, where substances are consumed unknowingly or under force, often presents a more compelling defense than voluntary intoxication. Understanding these nuances is essential in legal contexts.



Intoxication occurs when substances like alcohol or drugs affect a person’s mental or physical state. In legal contexts, intoxication can sometimes be used as a reason to explain one’s actions. The official description of intoxication is a disturbance in someone’s mind or body due to these substances. Intoxication can be voluntary or involuntary. Voluntary intoxication happens when someone knowingly consumes a substance that can intoxicate them. Courts generally do not see this as a good defense.

On the other hand, involuntary intoxication happens when someone takes a substance without knowing or is forced to. This can be a stronger defense in court, with some comparing its reasoning to the insanity defense. The A.C.A. § 5-2-207 law provides a clear position on intoxication, distinguishing between self-induced and non-self-induced types. In court, the intent behind an action, known as mens rea, is essential.

When a crime is done recklessly, voluntary intoxication weakens its defense. If someone drives under the influence and causes harm, the penalties are severe, reflecting society’s strong disapproval. In conclusion, while intoxication can affect decision-making, its use as a defense varies, with involuntary intoxication often seen as more defensible than voluntary intoxication.

Modification History

File Created:  07/17/2018

Last Modified:  09/26/2023

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This work is licensed under an Open Educational Resource-Quality Master Source (OER-QMS) License.

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