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 Idaho, as in many states, voluntary intoxication is generally not a defense to criminal charges. Idaho law holds that voluntary intoxication does not excuse criminal behavior, meaning that a defendant cannot argue they were unable to form the intent to commit a crime due to being under the influence of drugs or alcohol. However, involuntary intoxication is a different matter. If a defendant can prove that they were involuntarily intoxicated—meaning they were drugged without their knowledge or consent, or otherwise did not choose to consume the intoxicating substance—they may have a valid defense if the intoxication rendered them incapable of understanding what they were doing or knowing that it was wrong. The distinction between voluntary and involuntary intoxication and its impact on a defendant's criminal responsibility is typically a matter for the jury to decide, based on the facts presented in the case. The specific statutes governing these defenses can be found in Idaho's penal or criminal code.