In California, Driving Under the Influence of Drugs is outlawed under California Vehicle Code section 23152(f) (VC), a subsection of the greater driving under the influence law. While the law uses a separate section to address the fact that it is illegal to drive while using drugs, stating, "It is unlawful for a person who is under the influence of any drug to drive a vehicle," the penalties for a California drug DUI are mostly the same as those for drunk driving.
One of the only differences is that while drivers who get an alcohol-related DUI can reinstate their driving privileges more quickly if they install an ignition interlock device (IID), but this option is not available to those caught using drugs while driving, as breathalyzers cannot detect drug use.