Alcohol and drugs
You are 30 years old and not on DUI probation. You are driving your own car, which needs no commercial license and carries no passengers for hire. At what blood alcohol concentration (BAC) does it become illegal for you to drive?
- 0.08% or higher. Correct answer
- 0.04% or higher.
- 0.01% or higher.
Why
With those four situations ruled out, the line is 0.08%, the limit for a driver over 21 in an ordinary vehicle. The handbook lists five limits in all and every other one is lower, which is why guessing the number is risky: 0.01% if you are under 21, 0.01% at any age while you are on DUI probation, 0.04% if you are driving a vehicle that requires a commercial driver's license, and 0.04% if you are driving a passenger for hire. So the number that applies to you depends on your age, your license, your passengers and your record. And 0.08% is not a safe-until mark. The handbook says almost everyone feels the effects of alcohol at levels below the legal limit, and that how impaired you are can be enough on its own: an arrest and a DUI conviction are possible with no BAC reading at all.
Where this comes from
California Driver's Handbook, June 2025 edition. The correct answer is 0.08% or higher.
The rule behind this one
California alcohol and drug rules for drivers goes through the whole topic, with the page of the California Driver's Handbook behind every rule.
More on alcohol and drugs
- You are 40 years old and on DUI probation. At what blood alcohol concentration (BAC) does it become illegal for you to drive?
- A friend is driving and you are in the passenger seat of their car. May you drink a beer?
- You are convicted of a DUI in California. What does DMV do to your driving privilege, and what must you do?
- You are arrested for DUI and the officer takes your driver's license. What are you given instead, and for how long?