California · DMV
California alcohol and drug rules for drivers
Four blood alcohol limits instead of one, a law that does not care whether a drug came from a pharmacy, and what a refusal to take a test costs you before any court is involved.
What counts as driving under the influence
The word that does the work in this topic is "any". California does not have one rule for drink and a softer rule for everything else: the offence is driving while something impairs your ability to drive, and the law does not ask where that something came from.
That is why the medicine-cabinet questions are worth studying. A prescription your doctor wrote, a syrup you bought for a cough, a combination of two things that would each be fine on their own: all of them can put you over the line, and none of them come with an exemption.
- The state's driving under the influence laws cover alcohol and drugs alike. Driving while impaired by alcohol, or by any drug that affects how safely you drive, is illegal. p. 72
- The law draws no distinction between illegal drugs and what a doctor or a pharmacist gives you. Both can change what you see, what you hear and how fast you react. p. 72
- Whatever your age, you may not drive once you have drunk too much alcohol in any shape, cough syrup included; nor after taking a drug that affects your driving, whether it came on prescription or off a shelf; nor after mixing the two so that you are less able to drive safely. p. 72
- Alcohol tolerance falls as you get older, which raises the risk of an alcohol-related driving problem. p. 72
- An officer who believes you are driving impaired may require a blood or urine test. Refuse it and DMV suspends or revokes your driving privilege for one year. p. 72
- Between the ages of 13 and 20, a conviction for riding a bicycle under the influence can suspend or delay your driving privilege for a year from the moment you would otherwise be eligible. p. 72
Four limits, not one
Everyone knows the headline number, and on a test the headline number is a trap, because it only applies to one group of drivers. The limit depends on how old you are, on what you are driving, and on whether a court has already put you on probation for this.
The second thing the handbook is careful about, and questions are careful about too, is that a legal reading is not a safe one. You can be arrested and convicted on how you were driving, with no number in evidence at all.
- It is illegal to drive with a blood alcohol concentration of 0.08% or higher once you are over 21. p. 73
- Under 21 the limit is 0.01% or higher, and the same 0.01% applies at any age to a driver on DUI probation. p. 73
- The limit is 0.04% or higher for driving a vehicle that requires a commercial driver license, and the same for carrying a passenger for hire. p. 73
- Your blood alcohol concentration measures how much alcohol is in your bloodstream. Almost everybody feels the effects of alcohol below the legal limits, and depending on how impaired you are you can be arrested and convicted of a DUI with no measurement at all. p. 73
- For the handbook table, one drink means 1.5 ounces of 80 proof spirits, 12 ounces of 5% beer or 5 ounces of 12% wine, and you subtract 0.01% for every 40 minutes between drinks. p. 73
- Drink and drugs are also out on the water: it is illegal to operate a boat, a jet ski, water skis, an aquaplane or a similar craft under the influence. p. 73
Carrying alcohol or cannabis in the vehicle
These rules apply when nobody has drunk anything at all, which is what makes them easy to get wrong. What matters is whether the container is sealed and where in the vehicle it is riding, and the glove box is specifically named because it is where people put things they think of as put away.
They also apply to passengers, not only to whoever is driving, with one narrow exception for vehicles where somebody else is doing the driving for a living.
- Drinking alcohol, or smoking or eating a cannabis product, is illegal while you are driving and also while you are riding as a passenger. p. 72
- Alcohol or cannabis you are carrying has to be in a sealed, unopened container. Once it is open it belongs in the trunk, or somewhere passengers do not sit. p. 72
- An open container of alcohol in the glove box is illegal. p. 72
- The rule does not reach a passenger in a bus, a taxi, a camper or a motorhome. p. 72
What happens after an arrest
Two separate things happen after a DUI arrest, and questions like to mix them up. DMV acts on your license administratively, before any judge sees the case; the court acts later, if there is a conviction. The deadlines that matter to you belong to the first one.
The most expensive sentence in the whole topic is about consent. By driving here you have already agreed to be tested when an officer suspects you, so refusing is not a way of avoiding the consequences: it is one of them.
- Driving in California means you have consented to a breath, blood or urine test if an officer suspects you of a DUI. Agreeing to a preliminary alcohol screening or a breath test does not exempt you from a blood or urine test for drugs, and refusing brings a suspension or a revocation. p. 74
- Under the administrative per se law, DMV has to suspend your driving privilege once you are arrested. p. 74
- The officer may take your license and hand you a temporary one that lasts 30 days. p. 74
- You have 10 days from the date of the arrest to ask DMV for an administrative hearing. p. 74
- A conviction means DMV suspends or revokes your driving privilege for one year. You also have to finish a DUI program, file a California insurance proof certificate (SR 22/SR 1P) and pay any reissue or restriction fees, and you may be required to fit an ignition interlock device. p. 74
- On top of that a conviction can bring up to six months in jail, a fine, an impounded vehicle with storage to pay for, and civil lawsuits if you seriously injured or killed somebody. p. 74
- Every DUI conviction stays on your driving record for 10 years, and another one inside that window lets the court or DMV add to the penalty. p. 74
Under 21: a different set of rules
For a driver under 21 the limit is effectively zero, and there is a second layer of law about simply having alcohol in the car. Both matter for the test, and the second one catches people who were not drinking and were not going to.
Note what the consequences reach. A court can fine you, take the license you have, or tell DMV to hold back the license you have not got yet.
- Under 21 you may not carry any alcoholic beverage inside a vehicle unless somebody 21 or older is with you, and even then the container has to be full, sealed and unopened; opened, it goes in the trunk or where passengers do not sit. Working for someone with an off-site liquor sales license is the exception, in closed containers. p. 75
- Get caught carrying alcohol and the vehicle can be impounded for as long as 30 days. A court can also fine you and take your license away for a year; with no license yet, it can ask DMV to hold your first one back for a year. p. 75
- An officer who suspects you have been drinking can require a hand-held breath test, a preliminary alcohol screening or another chemical test. p. 75
- A conviction with a blood alcohol concentration of 0.01% or higher lets DMV revoke your driving privilege for a year, and you have to complete a licensed DUI program. p. 75
- A screening that reads 0.05% or higher lets the officer require a breath or blood test, and a later test at 0.05% or higher can mean arrest for a DUI and a suspended driving privilege. p. 75
Why this matters: California by the numbers
- Driving under the influence was the primary cause of 34,641 California crashes in 2024. What causes crashes
- Open container of alcohol while driving: $363 and 1 DMV point. The full cost of a ticket
Now practice it
22 questions on alcohol and drugs in the California question bank, each on its own page with the answer and the explanation, or take the full practice test.
Sources
How we write and check this material: our methodology.