Intoxication due to a defendant’s voluntary consumption of drugs or alcohol isn’t usually a defense to criminal charges—but if the intoxication was involuntary, it may be a defense on the basis that the defendant did not understand what he was doing or that what he was doing was wrong. And some states allow a defendant to assert a defense that his voluntary intoxication prevented him from forming the specific intent to commit the crime (attempted murder, for example). But this is a question of fact that the jury will usually determine.

The availability and definition of any defense to criminal charges based on the defendant’s voluntary or involuntary intoxication is usually located in a state’s statutes—often in the penal or criminal code.

In Oklahoma, voluntary intoxication is generally not a defense to criminal charges. The state's legal stance is that individuals are responsible for their actions, even if they are under the influence of drugs or alcohol. However, there are exceptions where involuntary intoxication may be considered a defense. Involuntary intoxication can occur if a person is forced to consume a substance or does so unknowingly, and as a result, lacks the capacity to understand the nature of their actions or to distinguish right from wrong. In such cases, the defense must prove that the intoxication was indeed involuntary. As for voluntary intoxication, Oklahoma law does allow for it to be considered when specific intent is an element of the crime. This means that if a defendant's voluntary intoxication prevented them from forming the specific intent required for a particular crime, such as attempted murder, it may be used as a defense. However, whether the intoxication actually had this effect is a question of fact for the jury to determine. The relevant statutes and case law would be found in Oklahoma's penal or criminal code and interpreted through court decisions.