Alcohol & Drug Laws
BAC Limits
- 0.08% BAC = illegal for drivers 21+
- 0.04% BAC = commercial drivers
- Any detectable alcohol = under 21 in most states
Penalties
- License suspension and fines
- Possible jail time for repeat offenses
- SR-22 insurance requirement after DUI conviction
Drugs & Medication
- Prescription drugs can impair driving.
- Medical marijuana rules vary by state.
- Field sobriety tests check impairment, not just alcohol.
Blood Alcohol Concentration (BAC)
In every U.S. state the adult per-se limit is 0.08% BAC, while drivers under 21 are held to near-zero tolerance (often 0.00–0.02%). Even one drink can push a smaller person above the limit, and impairment begins well before the legal line.
Open Container and Public Drinking
Open containers of alcohol are banned in the passenger area of a moving vehicle in most states. Drivers can be cited even if a passenger holds the drink. Keep any alcohol sealed in the trunk.
Refusing a Test
Implied-consent laws mean that refusing a breath or blood test triggers an automatic license suspension, separate from any criminal charge. The penalty for refusal is often longer than the penalty for a first offense.
Minimizing Risk
Plan a designated driver, rideshare, or taxi before you drink. A DUI stays on your record for years and raises insurance dramatically — far costlier than a short ride home.
Field Sobriety and Breath Tests
Officers may ask you to perform roadside coordination tests and blow into a breathalyzer. Under implied-consent laws, declining usually brings an automatic suspension. The readings feed both the roadside decision and the formal case.
State Variations
Some states add enhanced penalties above 0.15% BAC, and a few apply different limits for commercial drivers (0.04%). Always learn the exact numbers for the state you drive in, because crossing a higher threshold changes the charge from a fine to a possible jail term.
Ride-Hailing and Friends
A designated driver is the cheapest insurance you will ever buy. If no one is sober, a rideshare costs less than a single night in jail and a year of raised premiums. Plan the ride before the first drink, not after.