Involuntary intoxication is a defense to criminal liability that arises when an individual commits a particular unlawful act while under the influence of intoxicating substances that were ingested involuntarily, and which rendered the individual incapable of understanding the nature of the acts committed.
Involuntary intoxication can be a complete defense to criminal liability in certain circumstances, such as when the intoxication was caused by medication that was prescribed by a doctor, or when the intoxication was caused by a substance that was unknowingly ingested (e.g. by drinking a spiked drink).
In the United States, the defense of involuntary intoxication is recognized by the Model Penal Code, which provides that an individual who committed a crime while under the influence of intoxicating substances that were ingested involuntarily should be found not guilty if they were so intoxicated that they could not form the necessary mens rea. However, the availability and scope of this defense varies by state and by the specific circumstances of the case.
[Last updated in March of 2023 by the Wex Definitions Team]