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 Texas, voluntary intoxication is generally not a defense to criminal charges. Texas Penal Code Section 8.04 states that voluntary intoxication does not constitute a defense to the commission of a crime. This means that being under the influence of drugs or alcohol by one's own decision does not excuse criminal behavior or negate the required mental state for a crime. However, involuntary intoxication can be a defense if it can be proven that the defendant was not aware of their actions or did not understand that what they were doing was wrong due to the intoxication. Involuntary intoxication might occur if someone is drugged without their knowledge or consent. The distinction between voluntary and involuntary intoxication is significant, and whether intoxication can be used as a defense, particularly regarding the formation of specific intent for crimes like attempted murder, is ultimately a question of fact for the jury to determine based on the evidence presented at trial.