Evidence that defendant used methamphetamine, alone, is insufficient to support a conviction for driving under the influence of drugs (Veh. Code, sec. 23152, subd. (a)); it must also be shown that the drug impaired defendant’s driving ability. Narcotics Detective Morales was surveilling a residence when he observed appellant enter, remain some five minutes and then leave. Morales radioed the information to other officers and shortly afterwards, Officer Savage saw appellant driving a truck and stopped him for failing to completely stop at the limit line. Morales responded to the location and, believing appellant to be under the influence of methamphetamine, arrested him for Vehicle Code section 23152, subdivision (a). Substantial evidence was produced at trial that appellant was under the influence of methamphetamine when he was arrested: he admitted recent methamphetamine use; he exhibited symptoms consistent with methamphetamine use; his urine tested positive for high levels of methamphetamine. There was also evidence that methamphetamine can impair a person’s judgment, focus, and psychomotor skills to make him an unsafe driver. However, there was no evidence that appellant’s use actually impaired his driving ability on the night of the arrest. Although appellant failed to completely stop at the limit line, the prosecution witness, a toxicologist, testified that this “common traffic violation” is not sufficient to establish a person is under the influence for driving purposes. The judgment was reversed due to insufficient evidence.