People v. Chaffey (1994) 25 Cal.App.4th 852, 856, explained: "A person whose intoxication is not voluntary is relieved from liability because of excusable mistake. 'What prevents the intoxication from being voluntary in these cases of fraud is not the trickery of the other person but the innocent mistake of fact by the one made drunk, and an actual ignorance of the intoxicating character of the liquor or drug has the same effect whether the mistake is induced by the artifice of another or not.' (Perkins on Criminal Law (2d ed. 1969) p. 895.)" In Chaffey, the defendant was convicted of driving under the influence of an intoxicating drug after she took an overdose of a prescription medication, intending to commit suicide, the medication rendered her unaware of her actions and she drove her car while in this condition. There was evidence that the label warned the medication could cause drowsiness. The trial court found the intoxication was voluntary because it was predictable that the defendant would become sleepy and "something would happen." Chaffey affirmed the conviction because the evidence supported the trial court's conclusion, although it noted that the evidence could have supported a conclusion that the defendant's intoxication was involuntary because she did not know, and a reasonable person would not have known, that an overdose of the medication could cause intoxication. (Id. at p. 857.)