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 Pennsylvania, voluntary intoxication is generally not a defense to criminal charges. However, there are exceptions where voluntary intoxication may be considered by the court, particularly in cases where specific intent is an element of the crime. For example, if a defendant is charged with a crime that requires the prosecution to prove they had a specific intent to commit the crime, such as attempted murder, the defendant may argue that due to intoxication, they were incapable of forming that specific intent. This does not absolve the defendant of liability but can potentially reduce the severity of the charges or the punishment. Involuntary intoxication, on the other hand, can be a defense if the defendant can show that they were intoxicated against their will or without their knowledge and, as a result, could not understand the nature of their actions or that their actions were wrong. The applicability of these defenses and the burden of proof rest on the defendant, and it is ultimately up to the jury to determine the facts of the case. The specifics of these defenses are outlined in Pennsylvania's statutes, particularly within the criminal code.