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 Montana, as in many states, voluntary intoxication is generally not a defense to criminal charges. This means that if a defendant was under the influence of drugs or alcohol by their own decision, they cannot use that intoxication to excuse their criminal behavior. However, if the intoxication was involuntary—meaning the defendant was forced to consume the substance or did so unknowingly—it may serve as a defense if it can be shown that the defendant was incapable of understanding the nature of their actions or that their actions were wrong. Additionally, Montana law does recognize that in certain cases, voluntary intoxication may prevent a defendant from forming the specific intent necessary for certain crimes, such as attempted murder. This is a complex area of law and whether intoxication can be considered a defense is ultimately a question of fact for the jury to decide, based on the specific circumstances of the case and the applicable state statutes.