In People v. Andersen (1994) 26 Cal.App.4th 1241, a blood test revealed that the defendant had a blood-alcohol level of 0.022 and a methamphetamine level of 156 nanograms per milliliter at the time of the test. ( Id. at pp. 1246-1247.) In rejecting the defendant's claim, the court explained, "The prosecution's theory of the case was that defendant was driving under the combined influence of alcohol and drugs. Since it is the combination that is alleged to have made defendant intoxicated, the level of alcohol alone in his blood is irrelevant. In these circumstances, an instruction couched in the language of former Vehicle Code section 23155, subdivision (a)(1), would have been highly confusing to the jurors. Accordingly, it was not error for the court to fail to give such an instruction." ( Id. at p. 1250.)