Tags show the kind of rule and whether it’s a written-test point or matters on the drive test (our tagging). Each rule links to its official source.
California’s DUI laws cover drugs as well as alcohol, and prescription or over-the-counter medicines, even cough syrup, count if they impair your driving.
Law Written test California Driver Handbook: Alcohol and Drugs
If you’re 21 or older, it’s illegal to drive with a blood alcohol concentration (BAC) of 0.08% or higher. (The handbook says "over 21"; California’s Vehicle Code (Section 23152) sets 0.08% for every driver, so it covers age 21 too; the handbook adds a 0.01% limit for drivers under 21.)
New York differs: BAC is usually measured from breath, blood, urine or saliva. Above 0.05% is evidence you’re impaired (DWAI), 0.08% or more is evidence of intoxication (DWI), and 0.18% or more is evidence of aggravated DWI. New York rule
Law Written test California Driver Handbook: Alcohol and Drugs
Under 21, it’s illegal to drive with any BAC of 0.01% or more; a DUI conviction at that level can bring a one-year revocation and a required DUI program.
New York differs: Zero Tolerance: a driver under 21 may not drive with any measurable BAC, 0.02% to 0.07%, a level one drink can reach. A DMV hearing decides the case and a finding isn’t a criminal conviction, but at 0.05% or more police can also charge DWAI or DWI in criminal court. New York rule
Law Written test California Driver Handbook: Alcohol and Drugs
If you’re on DUI probation, any BAC of 0.01% or more makes driving illegal, whatever your age.
Law Written test California Driver Handbook: Alcohol and Drugs
The BAC limit is 0.04% when driving a vehicle that requires a commercial license or when carrying passengers for hire.
Law Written test California Driver Handbook: Alcohol and Drugs
Being under the legal BAC limit doesn’t make it safe to drive; depending on your impairment, you can be arrested and convicted of DUI even without a BAC reading.
Law Written test California Driver Handbook: Alcohol and Drugs
One drink means 1.5 oz of 80-proof liquor, 12 oz of 5% beer, or 5 oz of 12% wine. BAC falls only about 0.01% for each 40 minutes between drinks.
New York differs: Each of those drinks raises a 150-pound man’s BAC by about 0.02%, and his body needs roughly an hour to clear it. Women generally take longer, and body weight changes the effect. New York rule
Safety advice California Driver Handbook: Alcohol and Drugs
No one in a vehicle, driver or passenger, may drink alcohol or smoke or eat cannabis products. The handbook exempts passengers in a bus, taxi, camper or motorhome; California’s Vehicle Code (Section 23229) limits that exemption to alcohol, so it doesn’t cover cannabis.
Law Written test California Driver Handbook: Alcohol and Drugs
Any alcohol or cannabis in the car must be sealed and unopened. The handbook says an opened container must ride in the trunk or an area where no one sits, not the glove box; for opened alcohol, California’s Vehicle Code (Section 23225) requires the trunk, and allows an area the driver and passengers don’t normally sit in only when the car has no trunk.
Law Written test California Driver Handbook: Alcohol and Drugs
Driving in California means you’ve agreed to take a blood, breath, or urine test if police suspect DUI; even after a breath test, you may need blood or urine for drugs.
Law Written test California Driver Handbook: Alcohol and Drugs
If you refuse a required blood or urine test for the first time, DMV will take away your driving privilege, by suspension or revocation, for one year.
New York differs: Refusing the test costs at least a 1-year revocation, or 18 months if you had a refusal or alcohol/drug violation in the past 5 years, plus a $500 civil penalty ($750 for a repeat). New York rule
Law Written test California Driver Handbook: Alcohol and Drugs
After a DUI arrest, DMV must suspend your license; the officer may take your card and give you a 30-day temporary license. You have 10 days to request a hearing.
Law Written test California Driver Handbook: Alcohol and Drugs
A DUI conviction brings a one-year suspension or revocation, a required DUI program, an SR 22/SR 1P insurance filing, fees, and possibly an ignition interlock device.
Changed 2026-01-01: The statewide ignition interlock (IID) rules for DUI offenders, due to end 2026-01-01, now run to 2033 (AB 366). From 2027, hit-and-run causing injury within 10 years of a separate DUI, reckless-driving or gross vehicular manslaughter violation can be a felony, and drivers who plead a DUI down to a lesser charge still get the warning that a future fatal DUI can be charged as murder (SB 907); a 3rd DUI within 10 years can be charged as a felony and a 5th or later is a felony (AB 1546). From 2031, gross vehicular manslaughter while intoxicated adds 3 points (AB 1685), and an injury DUI with 4+ priors in 10 years means revocation with no reinstatement for 6 years, then an IID (AB 1687). The handbook doesn’t say this yet. California bill AB 366 (2025-26)
New York differs: A DWI or aggravated DWI conviction means installing, at your own cost, an ignition interlock (a breath tester you must pass to start the car) on every vehicle you own or drive for at least 12 months; a court may end it after 6. New York rule
Law Written test California Driver Handbook: Alcohol and Drugs
DUI convictions stay on your driving record for 10 years, and another DUI within those 10 years may bring an additional penalty from the court or DMV.
Law Written test California Driver Handbook: Alcohol and Drugs
Under 21, you may carry alcohol in a car only with certain adults along, unless you’re working for a licensed seller. The handbook says anyone 21 or older; California’s Vehicle Code (Section 23224) names a parent, a responsible adult relative, another adult a parent designated, or a legal guardian. The handbook also says the alcohol must be in a full, sealed, unopened container or, if opened, in the trunk or where no passenger sits (not the glove box); in a car with a trunk, California’s Vehicle Code (Section 23225) requires the trunk.
Law Written test California Driver Handbook: Alcohol and Drugs
Under 21 and caught with alcohol in the car? It can be impounded up to 30 days, and a court may impose a fine and a one-year license suspension.
Law Written test California Driver Handbook: Alcohol and Drugs
For drivers under 21, a preliminary screening of 0.05% or more can lead to a required breath or blood test, and a later 0.05%+ result to a DUI arrest.
Law Written test California Driver Handbook: Alcohol and Drugs
Beyond DMV’s actions, a DUI conviction can bring up to six months in jail, a fine, and impound of your car, possibly with storage fees; causing serious injury or death while impaired by alcohol or drugs can also lead to civil lawsuits.
Law Written test California Driver Handbook: Alcohol and Drugs
A 13- to 20-year-old convicted of cycling while impaired by alcohol or drugs can have their license suspended, or their first license put off, for a year after they become eligible to drive.
Law Written test California Driver Handbook: Alcohol and Drugs