California · Handbook chapter 9 · 5 min read
Chapter 9: Alcohol and drugs
California DUI law for alcohol, cannabis and medications: BAC limits by age and license type, open container rules, implied consent, what happens after a DUI arrest or conviction, and the extra rules for drivers under 21.
Why this chapter matters
Every permit test includes questions on blood alcohol limits and DUI penalties. The limits differ by age and by type of driving, so learn the full list, not just 0.08%.
The basic rule
It is illegal to drive under the influence of alcohol or any drug that affects your ability to drive safely. The law makes no distinction between illegal drugs and medicines from a doctor or pharmacy. At any age, you may not drive after:
- Drinking too much alcohol in any form, including medicines such as cough syrup.
- Taking any drug, prescription or over-the-counter, that affects your driving.
- Combining alcohol and drugs in a way that impairs you.
Read medication labels and know how any drug affects you. Tolerance to alcohol also falls as you get older.
Blood alcohol concentration (BAC) limits
BAC measures how much alcohol is in your blood. A BAC of 0.10% means 0.10 grams of alcohol per 100 milliliters of blood. It is illegal to drive with a BAC of:
| Driver | Illegal BAC |
|---|---|
| Aged 21 or older | 0.08% or higher |
| Under 21 | 0.01% or higher |
| Anyone on DUI probation | 0.01% or higher |
| Driving a vehicle that needs a commercial license | 0.04% or higher |
| Driving passengers for hire | 0.04% or higher |
Being under the limit does not mean you are safe to drive. Almost everyone is affected below the legal limit, and you can be arrested and convicted of DUI without any BAC measurement if you are impaired.
Measuring a drink
The handbook counts one drink as 1.5 oz of 80-proof liquor, 12 oz of 5% beer or 5 oz of 12% wine. As a rough guide, BAC drops by about 0.01% for every 40 minutes between drinks. How quickly BAC rises depends on the number of drinks, your sex and your body weight, and even one drink can affect your driving.
Open containers, alcohol and cannabis
- No one in the vehicle, driver or passenger, may drink alcohol or smoke or eat cannabis products while driving or riding in the vehicle.
- Any alcohol or cannabis you carry must be sealed and unopened. If it has been opened, it must go in the trunk or somewhere passengers do not sit. The glove box is not allowed.
- These rules do not apply to passengers in a bus, taxi, camper or motorhome.
Implied consent and DUI arrests
- By driving in California, you consent to a breath, blood or urine test if an officer suspects DUI. Even after a preliminary alcohol screening (PAS) or breath test, you may be asked for blood or urine to test for drugs.
- Refusing a test means the DMV will suspend or revoke your driving privilege for one year.
- After a DUI arrest, the Administrative Per Se law requires the DMV to suspend your license. The officer may take your license and give you a 30-day temporary license.
- You have 10 days from the arrest to request a DMV administrative hearing.
DUI convictions
A DUI conviction means a one-year suspension or revocation by the DMV. You must also:
- Complete a DUI program.
- File a California Insurance Proof Certificate (SR 22/SR 1P).
- Pay any reissue or restriction fees.
- Possibly install an ignition interlock device (IID).
Other possible penalties include up to six months in jail, a fine, and impoundment of your vehicle with storage fees. If you cause injury or death, you may also be sued. DUI convictions stay on your record for 10 years, and a further DUI in that time can bring heavier penalties.
Drivers under 21
Carrying alcohol
- You may not carry alcohol in a vehicle unless someone aged 21 or older is with you, and the container is full, sealed and unopened. Opened alcohol must be in the trunk or where passengers do not sit. (Exception: you may carry closed containers while working for someone with an off-site liquor sales license.)
- If you are caught with alcohol, your vehicle can be impounded for up to 30 days, and the court may fine you and suspend your license for one year, or ask the DMV to delay your first license by up to one year.
Drinking
- An officer who suspects you have been drinking can require a hand-held breath test, a PAS or another chemical test.
- A DUI conviction with a BAC of 0.01% or higher can lead to a one-year revocation and a required licensed DUI program.
- If a PAS shows 0.05% or higher, the officer may require a further breath or blood test. If that later test shows 0.05% or higher, you may be arrested for DUI and your driving privilege may be suspended.
Bicycles count too
If you are 13 to 20 and convicted of riding a bicycle under the influence, your driving privilege may be suspended or delayed for one year once you become eligible.
Alcohol and drugs are also illegal when operating a boat, jet ski or similar vessel.
Frequently asked questions
What is the legal BAC limit in California?
0.08% for drivers 21 and older, 0.01% for drivers under 21 and anyone on DUI probation, and 0.04% for commercial drivers and anyone driving passengers for hire.
Can I be arrested for DUI on prescription medicine?
Yes. The law treats legal medicines the same as illegal drugs if they affect your ability to drive safely.
What happens if I refuse a chemical test?
The DMV will suspend or revoke your driving privilege for one year.
How long do I have to ask for a DMV hearing after a DUI arrest?
10 days from the date of the arrest.
Can I keep an open bottle of wine in the glove box?
No. An opened container of alcohol must be kept in the trunk or another area where passengers do not sit, and the glove box does not count.
How long does a DUI stay on my driving record?
10 years.
Based on the California Driver's Handbook (DL 600, revised June 2025), California DMV, licensed CC BY-NC 4.0.