Alcohol, drugs and driving

Short answer

It is illegal to drive with a blood alcohol concentration (BAC) of 0.08% or more if you are 21 or older (0.05% in Utah). Drivers under 21 face zero tolerance limits of 0.02% or lower. Drugs, including legal ones, can also make driving illegal.

Alcohol and drugs slow your reactions, blur your judgment and make you feel more confident than you should. Every state treats impaired driving as a serious crime.

The legal limits

21 and older: 0.08% BAC in every state except Utah, which uses 0.05%.
Under 21: zero tolerance. The limit is 0.02% or lower in every state, and some use 0.01% (California) or 0.00%.
Commercial drivers: 0.04%.
You can be charged below these limits if your driving is impaired.

Implied consent

By driving, you have already agreed to a breath, blood or urine test if an officer suspects impaired driving. Refusing the test usually means an automatic license suspension, often longer than for failing it.

Drugs count too

Marijuana, many prescription medicines and some over-the-counter cold and allergy medicines can impair you. Read the label. If it warns about drowsiness or operating machinery, do not drive. A prescription is not a defense if you are impaired.

Only time sobers you up

Coffee, a cold shower or fresh air do not lower your BAC. Your body clears alcohol at a fixed rate. If you have been drinking, get a ride or wait.

State differencesPenalties, refusal suspensions and the exact under-21 limit vary by state. Check your state handbook.

In VirginiaUnder 21, it is illegal to drive with a BAC of 0.02% or more. By driving in Virginia you agree to a breath or blood test if arrested for DUI; a first refusal means a 1-year license suspension. See all Virginia rules

Check yourself

Quick quiz

7 questions with explanations.

Questions people ask

Can I drive if I only had one drink?

Even one drink affects reaction time, and under 21 any measurable amount can be illegal. The safe choice is not to drive after drinking.

What does zero tolerance mean?

For drivers under 21, the legal limit is close to zero: 0.02% or lower, depending on the state.

Sources

Last checked October 2026. Laws change; your state's official handbook is the final word.