Being drunk or high usually isn’t a defense to criminal charges (see Being Drunk: A Defense to Criminal Charges?), but the law differs somewhat where defendants get drunk or high through no fault of their own.
Intoxication is typically “involuntary” when someone forces drugs or alcohol upon the defendant or tricks the defendant into consuming them. It may also be involuntary when caused by medication that a doctor has prescribed or administered. But involuntary intoxication generally isn’t a defense where a substance has a particularly severe effect on a defendant who chose to consume the substance. And isn’t necessarily an automatic defense—the defendant must typically prove a very high level of intoxication.
In practice, involuntary intoxication defenses rarely succeed.
Whereas voluntary intoxication may, in limited circumstances, prevent a defendant from forming the specific intent required for certain crimes, involuntary intoxication may be a complete defense to a variety of charges. Depending on the law of the state, involuntary intoxication may excuse what would normally be criminal conduct if it:
Example: Joe and a group of friends are playing cards at his house. They’re drinking beer; Joe is drinking soda. One of his friends slips a pill containing a synthetic drug into Joe’s soda can and Joe unwittingly consumes it. He soon goes into a complete stupor. Not knowing what he’s doing, he begins to attack his friends. If charged with assault, Joe may have a viable involuntary intoxication defense.