A DUI at a 0.18 BAC carries penalties well beyond a standard first-offense case: the reading is more than double the 0.08 legal limit and triggers aggravated or “high-BAC” DUI charges in most states, meaning mandatory jail time, extended license suspension, a required ignition interlock, and financial consequences that stretch for years.1Office of the Law Revision Counsel. 23 U.S. Code 163 – Safety Incentives to Prevent Operation of Motor Vehicles by Intoxicated Persons If you searched “1.8 BAC,” the reading in your paperwork is almost certainly 0.18; a literal 1.8% BAC would be fatal, as any level above roughly 0.40 carries a risk of death.
Why 0.18 Triggers Enhanced Charges
A standard first-offense DUI is typically a misdemeanor. A 0.18 changes that because roughly 45 states and the District of Columbia impose enhanced penalties at elevated BAC levels, with the most common trigger points set at 0.15, 0.16, or 0.20.2National Conference of State Legislatures. Increased Penalties for High Blood Alcohol Content A 0.18 clears the enhancement threshold in the large majority of those states.
Enhanced charges bring stiffer mandatory minimums, higher fines, and sometimes a different offense classification altogether. In some jurisdictions, a BAC at or above twice the legal limit can be charged as an aggravated or felony DUI even on a first offense. Certain circumstances push a high-BAC case further into felony territory:
- Causing injury or death while driving at 0.18 almost always results in felony charges.
- Having a child passenger triggers separate child endangerment charges in most states, with additional mandatory jail time and fines.
- Driving on a suspended or revoked license frequently elevates the DUI to a felony.
- A prior DUI combined with a high BAC compounds the severity dramatically.
Jail, Fines, and Probation
The specific penalties depend on your state, your record, and any aggravating circumstances. For a first-time high-BAC DUI, the general picture looks like this:
- Jail time. A first-offense DUI can carry up to six months to a year. High-BAC enhancements add mandatory minimums in many states, commonly 5 to 10 days that a judge cannot waive, even for first-time offenders.
- Fines. Base fines typically run $500 to $2,000 or more. High-BAC enhancements push them higher, and with court costs, assessment fees, and surcharges, total out-of-pocket costs frequently reach several thousand dollars.
- Probation. Courts routinely impose one to three years, which may include random drug and alcohol testing, travel restrictions, and regular check-ins with a probation officer.
- Alcohol education and treatment. Nearly every jurisdiction requires completion of a state-approved program. At 0.18, expect placement in an extended treatment program rather than a basic awareness class. Completion is almost always required before you can get your license back.
- Community service. Courts frequently order anywhere from 40 to several hundred hours, particularly as an alternative to additional jail.
License Suspension and the Interlock Requirement
Most states trigger an administrative license suspension the moment you’re arrested or your BAC test comes back above the limit, before you ever see a courtroom. For a first offense with a high BAC, suspension periods typically run 90 days to a full year. Repeat offenses or an accident tied to the reading extend that timeline significantly.
Reinstatement after the suspension is rarely automatic. You’ll generally need to pay reinstatement fees, provide proof of completed alcohol education, and in most cases install an ignition interlock device on your vehicle. As of early 2026, roughly 34 states and D.C. require interlock devices even for first-time DUI offenders, and several additional states mandate them specifically when BAC exceeds 0.15.3Insurance Institute for Highway Safety. Alcohol Interlock Laws by State At 0.18, you’ll almost certainly need one.
The device requires a clean breath sample before the engine will start, with periodic rolling retests while you drive. Installation typically costs $70 to $150, with monthly lease and calibration fees between $50 and $120. You pay all of it. Most states require the device for six months to two years depending on your BAC and any prior offenses. Some states allow a restricted license with the interlock during what would otherwise be a hard suspension, so the device can actually get you back on the road sooner.
Insurance and SR-22 Filings
A DUI conviction reshapes your auto insurance picture for years. Insurers classify you as a high-risk driver, and premiums jump accordingly. National rate data shows a single DUI raises annual premiums by roughly 90% on average, adding more than $2,000 per year compared with a clean-record driver. Some insurers cancel the policy entirely, forcing you to shop with high-risk specialty carriers at even steeper rates.
Most states also require you to file an SR-22, or an FR-44 in a few states, which is a certificate proving you carry at least the state-minimum liability coverage. The requirement typically lasts about three years but can extend to five depending on the state and offense. Letting the SR-22 lapse, even briefly, usually triggers an automatic license re-suspension, so the filing becomes another recurring obligation to manage.
Long-Term Record Consequences
A DUI conviction creates a criminal record that, in most states, stays with you permanently unless you successfully petition for expungement or sealing. It shows up on standard background checks, which means prospective employers, landlords, and licensing agencies can see it.
Employers can legally decline to hire someone with a DUI when the conviction is relevant to the job, especially positions involving driving, heavy equipment, or work with vulnerable populations. A high-BAC reading raises red flags that quietly close doors in competitive markets. Housing applications increasingly include criminal background checks, and a DUI can complicate applications for federal student aid, military service, security clearances, and government employment.
Professional licensees face additional exposure. If you hold a state-issued license in nursing, law, teaching, real estate, medicine, or commercial aviation, you likely have a mandatory reporting obligation. Many boards require disclosure of a DUI arrest or conviction within 30 days, and failure to report often draws harsher discipline than the DUI itself because the board treats it as dishonesty. Outcomes range from a formal reprimand to suspension or revocation. A 0.18 signals a more serious problem than a borderline reading, and boards factor that in.
CDL holders face an entirely separate layer under federal regulations. A first DUI conviction, whether you were driving a commercial vehicle or your personal car at the time, results in a one-year disqualification from operating any commercial motor vehicle. A second DUI in a separate incident triggers a lifetime disqualification.4eCFR. 49 CFR 383.51 – Disqualification of Drivers There is no restricted CDL or hardship exception during the disqualification period.
Travel outside the U.S. also gets harder. Canada is the most consequential example: its immigration law treats impaired driving as “serious criminality” because the Canadian equivalent offense carries a maximum sentence of up to 10 years, and a single U.S. DUI conviction, even a misdemeanor, can make you inadmissible.5Justice Laws Website. Immigration and Refugee Protection Act SC 2001 c 27 – Section 36 The old “deemed rehabilitation” path that once allowed entry after enough time passed no longer applies to impaired driving. You now have to apply for criminal rehabilitation through Canadian immigration, which is a lengthy process.
Defending the Case
The complexity of a high-BAC DUI case makes experienced legal counsel worth the investment. A defense attorney can evaluate whether the traffic stop was lawful, whether the breath or blood test was properly administered and calibrated, and whether your rights were respected during the arrest. BAC testing is not infallible. Improper calibration, contaminated samples, rising blood alcohol at the time of the test, and medical conditions like acid reflux can all produce inflated readings.
The administrative side matters just as much. The license suspension hearing is typically separate from the criminal case and often has a very short window to request, sometimes as little as 10 days after arrest. Missing that deadline means the suspension proceeds unchallenged. Defense counsel can negotiate plea agreements that reduce charges or minimize mandatory minimums, advocate for restricted driving privileges, and represent you in any professional licensing proceedings that follow.
If you cannot afford a private attorney, you have a constitutional right to court-appointed counsel for any DUI charge that carries potential jail time, which high-BAC cases almost always do. Ask the court about appointed counsel at your first appearance.
A Note on the Physical Reading
At a BAC between 0.15 and 0.20, you lose significant control over balance and voluntary muscles. Walking and talking become difficult, pain sensation is altered, and nausea is common. The gag reflex weakens, creating a choking risk if you vomit. Blackouts can begin in this range. If a BAC is climbing toward 0.20 or beyond, alcohol poisoning becomes a genuine medical emergency, and 911 is the right call rather than assuming the person will sleep it off.