VC 23152(f): Driving Under the Influence of Drugs in California

Vehicle Code 23152(f) prohibits driving a motor vehicle while under the influence of any drug. Unlike alcohol DUI, California has no legal limit for drugs, meaning any level of impairment can support a conviction. This creates both challenges and uncertainties, as proving drug impairment relies heavily on officer observations, field tests, and expert interpretation of toxicology results.

Text of Vehicle Code 23152(f)

California Vehicle Code Section 23152(f) states:

It is unlawful for a person who is under the influence of any drug to drive a vehicle.

The statute uses broad language that encompasses virtually any substance capable of affecting the nervous system and impairing driving ability.

What Qualifies as a Drug Under VC 23152(f)

The term drug under this statute includes a wide range of substances beyond illegal narcotics:

Illegal Controlled Substances

Cocaine, heroin, methamphetamine, MDMA, LSD, and other Schedule I and II controlled substances all qualify as drugs under VC 23152(f). Even small amounts that produce any impairment can support charges.

Marijuana

Despite California’s legalization of recreational marijuana, driving under the influence of cannabis remains illegal. There is no per se THC limit in California, so impairment must be proven through other evidence. The presence of THC metabolites alone does not establish impairment, as metabolites can remain detectable long after any impairing effects have worn off.

Prescription Medications

Legally prescribed medications can result in drug DUI charges if they impair driving ability. Common culprits include opioid pain medications such as oxycodone, hydrocodone, and morphine; benzodiazepines like Xanax, Valium, and Ativan; sleep aids including Ambien and Lunesta; muscle relaxants; certain antidepressants and antipsychotics; and some antihistamines. Having a valid prescription provides no defense if the medication actually impaired driving ability.

Over-the-Counter Medications

Some non-prescription drugs can impair driving and support DUI charges. Diphenhydramine (Benadryl), sleep aids, and certain cold medications may cause drowsiness or cognitive impairment sufficient to violate VC 23152(f).

Elements the Prosecution Must Prove

To secure a conviction under VC 23152(f), the prosecution must prove each element beyond a reasonable doubt:

Element 1 – The Defendant Drove a Motor Vehicle

As with all DUI offenses, the prosecution must establish that the defendant operated a vehicle. Evidence typically comes from officer observations, witness testimony, or accident investigation.

Element 2 – Under the Influence of a Drug

The defendant must have been under the influence of a drug while driving. Under the influence means the drug affected the nervous system, brain, or muscles to the degree that the defendant could no longer drive with the caution of a sober person using ordinary care.

Unlike alcohol DUI under VC 23152(b), there is no numerical threshold to satisfy. The prosecution must prove impairment through circumstantial evidence and expert testimony.

How Drug DUI Is Investigated

Drug DUI investigations differ significantly from alcohol DUI stops because no roadside breath test can measure drug levels.

Initial Observations

Officers note driving patterns, physical appearance, behavior, speech, and any visible signs of drug use. Dilated or constricted pupils, rapid or slow speech, tremors, unusual behavior, and the odor of marijuana are commonly documented.

Field Sobriety Tests

Standard field sobriety tests are administered, though their reliability for detecting drug impairment is less established than for alcohol. Officers may also conduct additional tests examining pupil response, muscle tone, and other physical indicators.

Drug Recognition Expert Evaluation

If drug impairment is suspected, a Drug Recognition Expert may conduct a 12-step evaluation protocol. DREs receive specialized training to identify drug categories based on physical symptoms. The DRE evaluation includes detailed examination of eyes, vital signs, muscle tone, and divided attention tests.

The DRE will form an opinion about what drug category is causing impairment, which directs subsequent chemical testing.

Chemical Testing

Blood testing is the standard method for confirming drug presence. Unlike breath tests, blood draws require either consent or a warrant in most circumstances. The sample is analyzed for the presence and concentration of suspected drugs and metabolites.

Urine testing may also be used but provides less precise information about current impairment since drugs remain detectable in urine longer than in blood.

Penalties for VC 23152(f) Violations

Drug DUI penalties mirror those for alcohol DUI, with severity increasing based on prior offenses and aggravating factors.

First Drug DUI

• Jail Time: 48 hours to 6 months
• Fines: $390-$1,000 plus assessments (~$1,800-$2,600 total)
• License Suspension: 6 months
• DUI Program: 3-9 months

Second Drug DUI

• Jail Time: 96 hours to 1 year
• Fines: $390-$1,000 plus assessments
• License Suspension: 2 years
• DUI Program: 18-30 months

Third Drug DUI

• Jail Time: 120 days to 1 year
• Fines: $390-$1,000 plus assessments
• License Suspension: 3 years
• DUI Program: 30 months

Fourth+ Drug DUI (Felony)

• Jail Time: 16 months to 3 years state prison
• Fines: Up to $1,000 plus assessments
• License Suspension: 4 years
• DUI Program: 30 months

Additional consequences may include probation, ignition interlock device installation (even for drug-only offenses), and drug treatment program participation.

Defenses to Drug DUI Charges

Drug DUI cases often present stronger defense opportunities than alcohol cases because proving impairment is more subjective.

No Actual Impairment

The mere presence of drugs in your system does not prove impairment. THC metabolites, for example, can remain detectable for weeks after use. Prescription medications taken as directed may produce positive results without causing meaningful impairment. The defense can argue that while drugs were present, they did not actually affect driving ability.

Challenging DRE Evaluation

Drug Recognition Expert evaluations are not infallible. Defense attorneys may challenge the officer’s DRE certification and training, deviations from standard protocol during the evaluation, alternative explanations for observed symptoms, and the scientific reliability of DRE opinions in general.

Medical Conditions Mimicking Impairment

Various medical conditions can produce symptoms that officers interpret as drug impairment. Diabetes, neurological conditions, inner ear problems, fatigue, and mental health conditions may affect balance, coordination, speech, and eye movements.

Challenging Blood Test Results

Blood test evidence can be challenged on multiple grounds including blood draw procedures and chain of custody, storage conditions and potential degradation, laboratory protocols and analyst qualifications, and whether detected levels correlate with impairment.

Unlawful Stop or Search

If the initial traffic stop lacked legal justification, or if blood was drawn without proper consent or warrant, the evidence may be suppressed regardless of what it shows.

Marijuana DUI Challenges

Marijuana DUI presents unique issues because THC affects individuals differently and remains detectable long after impairment fades. California has rejected proposals to establish a per se THC limit, recognizing that correlation between blood THC levels and impairment is unreliable.

Chronic marijuana users may have elevated baseline THC levels without being impaired, while occasional users might be impaired at lower detected levels. This scientific uncertainty creates defense opportunities that don’t exist in alcohol cases.

Related Statutes

• VC 23152(g) – Driving under the combined influence of alcohol and any drug
• VC 23152(a) – Driving under the influence of alcohol
• VC 23152(c) – Driving while addicted to drugs
• VC 23153 – DUI causing injury, applicable when drug impairment causes harm to another
• Health and Safety Code 11550 – Being under the influence of a controlled substance, a separate misdemeanor that doesn’t require driving

Contact a California Drug DUI Defense Attorney

Drug DUI cases require attorneys who understand both the law and the science behind drug impairment evidence. Toxicology, pharmacology, and DRE protocols all come into play when building an effective defense.

KN Law Firm has experience defending clients against drug DUI charges throughout Los Angeles County. Contact us at (888) 950-0011 for a free consultation to discuss the specific circumstances of your case.