The legal drunk driving limit in the United States is a blood alcohol concentration of 0.08% for most adult drivers. At or above that number, the test result alone is enough to convict you, regardless of how sober you felt behind the wheel. Commercial drivers are held to 0.04%, drivers under 21 face near-zero tolerance in every state, and Utah has lowered its limit to 0.05%. You can also be charged with impaired driving at any BAC if your behavior shows you weren’t fit to drive.
The 0.08% Per Se Standard
Every state enforces 0.08% as the BAC limit for standard adult drivers. The uniformity comes from federal pressure: under 23 U.S.C. ยง 163, the federal government withholds up to 6% of a state’s federal-aid highway funds if the state fails to enforce a per se drunk driving offense at 0.08% or above.1Office of the Law Revision Counsel. 23 USC 163 – Safety Incentives to Prevent Operation of Motor Vehicles by Intoxicated Persons All 50 states adopted the limit.
“Per se” is Latin for “by itself.” In practice, it means the prosecutor doesn’t have to prove you were swerving, slurring, or failing field sobriety tests. If the chemical test reads 0.08% or higher, the number is the case. A jury can convict on that alone.
Lower Limits for Specific Drivers
Commercial Drivers: 0.04%
If you hold a commercial driver’s license, the per se limit is half the standard threshold. Federal regulations set the lower bar because commercial vehicles are heavier, harder to stop, and often carry passengers or hazardous cargo.2eCFR. 49 CFR 383.51 – Disqualification of Drivers
The consequences for CDL holders are harsh. A first alcohol-related conviction while driving any motor vehicle results in a one-year CDL disqualification. If you were hauling hazardous materials, the disqualification jumps to three years. A second conviction in a separate incident triggers a lifetime ban from holding a CDL, and that lifetime disqualification also applies to refusing a chemical test.2eCFR. 49 CFR 383.51 – Disqualification of Drivers
One detail trips up commercial drivers: these rules apply whether you’re on or off duty. A DUI conviction in your personal pickup truck on a Saturday night still costs you your commercial license.3Federal Motor Carrier Safety Administration. Is a Driver Disqualified for Driving a CMV While Off-Duty With a Blood Alcohol Concentration Over 0.04 Percent?
Drivers Under 21: Zero Tolerance
Every state has a zero tolerance law that makes it illegal for a driver under 21 to drive with any measurable amount of alcohol. The exact threshold ranges from 0.00% to 0.02% depending on the state, with the slightly-above-zero cutoff designed to avoid false positives from mouthwash, cold medicine, or naturally occurring trace alcohol. No evidence of actual impairment is required: alcohol in a minor’s system is enough.
Penalties for an underage DUI are typically administrative for a first offense, with the most common consequence being an immediate license suspension of six months to a year. If a minor’s BAC reaches 0.08% or higher, they face adult DUI charges on top of the zero tolerance violation.
Utah: 0.05%
Utah is currently the only state with a per se limit below 0.08%, having lowered it to 0.05% in 2018. A driver who would be legal in the other 49 states can face criminal charges after crossing into Utah with the same BAC. For many people, the gap between 0.05% and 0.08% is roughly one drink. The National Transportation Safety Board has recommended a nationwide 0.05% limit, but no other state has adopted one so far.
You Can Be Charged Below the Limit
The per se number gets the most attention, but it isn’t the only path to a DUI charge. Every state also has impairment-based drunk driving laws, and those have no minimum BAC. If an officer stops you at 0.05% and your driving pattern, speech, or field sobriety test performance suggests impairment, you can face the same charge as someone who blew a 0.10%. Some states have separate lower-threshold offenses for drivers who are impaired but below the per se limit.
Someone who has two drinks, feels fine, and tests under 0.08% can still be arrested if the officer observes enough signs of impaired driving. The 0.08% line means you’re automatically guilty above it. It doesn’t mean you’re automatically safe below it.
How Many Drinks That Is
The CDC defines one standard drink as containing 0.6 ounces of pure alcohol: 12 ounces of regular beer at 5% alcohol, 5 ounces of wine at 12%, or 1.5 ounces of distilled spirits at 40% (80-proof).4Centers for Disease Control and Prevention. About Standard Drink Sizes A pint of craft IPA at 7% alcohol is closer to two standard drinks than one.
Roughly four standard drinks within two hours can push an average 180-pound man to around 0.08%. Women generally reach higher BAC levels than men after drinking the same amount, even adjusted for body weight, largely because of differences in total body water content.5PMC (National Center for Biotechnology Information). Gender Differences in Moderate Drinking Effects Fatigue, food, hydration, and the pace of drinking all shift the number. No universal formula tells you exactly where you stand.
Penalties for Exceeding the Limit
A standard first-offense DUI is typically a misdemeanor, but calling it “just a misdemeanor” understates the damage. Common penalties include up to six months in jail, fines of $500 to $2,000 or more, and a license suspension of around 90 days. Many states allow a restricted license during the suspension, often only with an ignition interlock device installed at your expense. Add mandatory alcohol education classes, court costs, and probation fees, and the total financial hit from a first DUI commonly lands between $5,000 and $10,000.
Most states don’t treat every DUI the same. A driver at 0.09% and a driver at 0.20% have technically committed the same base offense, but many states create additional tiers, often called “extreme” or “aggravated” DUI, that kick in at 0.15% or 0.20% BAC. Those elevated charges carry mandatory minimums, longer jail sentences, and steeper fines.
Ignition interlock devices have become central to DUI enforcement. Thirty-one states and the District of Columbia require an interlock for all DUI offenders, including first-timers. Several additional states require them specifically for high-BAC offenders or repeat offenders.6National Conference of State Legislatures. State Ignition Interlock Laws The device typically stays on the vehicle for at least a year, and the offender pays installation and monthly monitoring costs.
A DUI charge becomes a felony under several circumstances:
- Causing injury or death to another person while driving drunk is a felony in virtually every state, with sentences ranging from a few years to decades depending on severity.
- Most states elevate the charge to a felony after two or three prior DUI convictions within a lookback period that varies from five years to a lifetime.
- Some states treat an extremely elevated BAC as a standalone basis for felony charges.
- Driving drunk with a child passenger triggers felony-level charges in many states.
- Getting a new DUI while your license is already suspended for a prior one can push the charge to felony level.
Refusing a Breath or Blood Test
Every state has an implied consent law. By holding a driver’s license and using public roads, you’ve agreed to submit to chemical testing if an officer has probable cause to suspect drunk driving. The U.S. Supreme Court has drawn lines around which tests the government can demand and what happens when you say no.
In Birchfield v. North Dakota, the Court ruled that breath tests are minimally invasive and can be required without a warrant as part of a lawful DUI arrest. Blood draws are different: because they involve piercing the skin and producing a biological sample, the Fourth Amendment requires a warrant before police can compel one.7Justia. Birchfield v. North Dakota, 579 U.S. ___ (2016) A state can criminalize refusing a breath test. It cannot criminalize refusing a blood test absent a warrant. Separately, in Missouri v. McNeely, the Court held that the natural decline of alcohol in the bloodstream does not automatically create an emergency that justifies skipping the warrant.8Justia. Missouri v. McNeely, 569 U.S. 141 (2013)
Refusing a breath test still carries serious consequences. Most states impose an automatic administrative license suspension for refusal, often longer than the suspension for a failed test. In many jurisdictions, the refusal itself can be introduced as evidence at trial, letting a prosecutor argue you refused because you knew you were guilty.
Long-Term Consequences Beyond Sentencing
Auto insurance premiums roughly double after a DUI conviction on average, adding close to $2,500 a year to the typical driver’s bill. The increase persists for three to five years in most states, sometimes longer.
A DUI conviction also creates a criminal record that follows you well past the end of your sentence. In many states, a DUI conviction cannot be expunged or sealed, meaning it appears on background checks indefinitely. Employers running checks for positions involving driving, government security clearances, or professional licensing will see it. Some career fields, including commercial trucking, law enforcement, and healthcare, may be permanently closed off. The conviction can also affect child custody proceedings, immigration status for non-citizens, and eligibility for certain educational programs.