Under California law, it does not matter how drunk, high, or sober the driver feels. Anyone who is driving while impaired by any substance or with a blood alcohol content (BAC) over the legal limit can be charged with driving under the influence (DUI).
Volitional Movement Standard In California, in order to be convicted of a DUI offense, there must be evidence of “volitional movement.” This means that simply sitting or sleeping in a vehicle is not, per se, illegal in California.