When the police believe a driver was impaired by both alcohol and drugs, California can charge a combined DUI under Vehicle Code 23152(g). These polysubstance cases are more complex than a straight alcohol DUI, and that complexity often works in the defense's favor.
What the prosecution has to prove
The prosecution must prove that the combination of substances actually impaired the driver. A modest alcohol level that would not support an alcohol DUI on its own is often paired with a claim that drugs pushed the driver over the line. That theory depends on connecting specific drug evidence to actual impairment at the time of driving, which is harder than it sounds.
Why these cases have weaknesses
There is no legal limit for most drugs, so the case turns on proof of impairment rather than a number. The presence of a drug in the blood shows exposure, not impairment, and for many drugs the detection window extends long past any effect. The Drug Recognition Expert evaluation that often supports these charges is a structured but contestable process. Pairing a low alcohol reading with a weak drug-impairment theory creates real room to challenge the case.
Prescription and lawful use
Using a prescription or a legal substance is not a crime; driving while actually impaired is what the statute reaches. The interaction between a prescribed medication and alcohol, and whether the driver was actually affected, are central questions.
Where to start
Combined DUI cases rise and fall on proof of impairment, which gives a prepared defense room to work. Use the free written case analysis below or call me directly. See also marijuana and drug DUI and how prescription drugs affect a DUI defense.