Yes, a .18 BAC is high. It sits more than twice the .08 legal limit that applies in every state, and it lands in the range most states classify as “aggravated,” “extreme,” or “high-BAC” DUI, which carries penalties well beyond a standard impaired-driving charge. Physically, a .18 is deep into the zone where confusion, vomiting, blackouts, and loss of motor control are common.
What .18 Does to Your Body
At the .08 legal limit, muscle coordination, judgment, and information processing are already impaired. By .15, the impairment is severe: far less muscle control, major loss of balance, and vomiting may occur.1NHTSA. Drunk Driving | Statistics and Resources A .18 falls squarely in the range where speech, vision, reasoning, and memory are all deeply compromised, gross motor skills are gone, and large gaps in next-morning memory are likely.
The .15 to .30 range brings confusion, vomiting, and drowsiness, with alcohol poisoning becoming a serious concern as you approach .30.2Cleveland Clinic. Blood Alcohol Content (BAC): What It Is and Levels A .18 isn’t immediately life-threatening for most adults, but it’s past the point where driving or any consequential decision is safe.
Why .18 Counts as an Aggravated DUI in Most States
Forty-four states plus the District of Columbia impose enhanced penalties when a driver’s BAC exceeds a specified threshold above .08.3Governors Highway Safety Association. Alcohol-Impaired Driving The exact cutoff varies by state. The most common trigger points are .15 and .16, though some states set theirs at .17, .18, or .20.4National Conference of State Legislatures. Increased Penalties for High Blood Alcohol Content A .18 clears the high-BAC threshold in the large majority of these jurisdictions, so you’ll usually face aggravated or extreme DUI charges rather than a standard offense.
The practical effect is that your case is treated as more serious from the start. Mandatory minimums apply, fine ranges go up, and the judge’s discretion to reduce penalties shrinks. If you’re assuming a first offense at .18 will be handled lightly because no one was hurt, that assumption is wrong in most places.
Jail, Fines, and Probation
High-BAC DUI charges carry mandatory jail time in most states, even for a first offense. States with a .15 threshold commonly require at least 48 hours of mandatory imprisonment for a first-time high-BAC offense. States with higher thresholds tend to impose longer mandatory minimums, with some requiring five to ten days behind bars when the BAC reaches .18 or .20.4National Conference of State Legislatures. Increased Penalties for High Blood Alcohol Content Repeat offenders face substantially longer sentences, and a second high-BAC conviction can escalate from a misdemeanor to a felony depending on the jurisdiction.
Fines for aggravated DUI convictions commonly range from roughly $1,000 to $5,000, and that’s before court costs, surcharges, and assessments, which frequently double or triple the base amount. Probation of one to three years is standard. Community service requirements of 100 hours or more appear in many state sentencing schemes, and nearly every jurisdiction mandates completion of an alcohol education or treatment program as a condition of the sentence. The evaluation that sets your treatment level is usually performed by a state-certified provider, and failing to complete the recommended program is a probation violation that can send you back to jail.
License Suspension and the Ignition Interlock
License suspension is virtually automatic after a high-BAC arrest, often before you’re convicted. Administrative suspensions triggered by failing or refusing a breath test typically last six months to a year for a first offense, and a conviction adds a separate judicial suspension on top. Repeat offenses or aggravating factors like causing an accident extend suspension periods significantly, sometimes to multiple years.
To drive again, most states require installation of an ignition interlock device after a high-BAC conviction. The device requires you to blow into a breath sensor before the car will start and logs every reading. Monthly lease fees start around $55 and can reach $100 or more depending on provider and state requirements, plus calibration appointments every one to three months at roughly $20 each. All told, the device costs most people $700 to $1,200 or more over a typical 12-month requirement.
Insurance and the SR-22
Insurance consequences last years. Insurers classify anyone with a DUI as a high-risk driver, and industry data shows drivers with a DUI conviction pay roughly double what they paid with a clean record. A .18 can push that higher, since some insurers further penalize aggravated offenses, and some carriers drop you entirely, forcing you into the high-risk market at worse rates.
Most states also require you to file an SR-22, a certificate your insurer submits to the state proving you carry at least the minimum required liability coverage. The SR-22 requirement typically lasts about three years, longer in some states. If your policy lapses during that period, your insurer notifies the state and your license is suspended again. The filing itself usually costs under $200 per year; the real expense is the inflated premium you’re locked into the whole time.
Jobs, Commercial Licenses, and Professional Licenses
A DUI conviction shows up on background checks, and an aggravated high-BAC offense reads worse than a standard DUI. Industries where safety is central, including transportation, healthcare, and education, often treat DUI convictions as disqualifying. Even where no explicit prohibition exists, a hiring manager who sees an aggravated DUI may move to the next candidate.
Commercial drivers face the most immediate career consequences. Federal regulations set the BAC limit for operating a commercial motor vehicle at .04, less than a quarter of .18. A first violation results in a one-year disqualification from operating any commercial vehicle, or three years if the driver was hauling hazardous materials. A second violation in a separate incident triggers a lifetime disqualification.5eCFR. 49 CFR 383.51 – Disqualification of Drivers The disqualification applies regardless of whether the driver was in a commercial vehicle at the time, as long as they hold a commercial license.
Professionals with state-issued licenses, including nurses, doctors, pharmacists, attorneys, and teachers, face a separate layer. Most licensing boards require self-reporting of any criminal conviction within a specified period, and failure to report can itself trigger discipline. Consequences range from mandatory monitoring or rehabilitation programs to suspension or revocation. Prior offenses, patient or client harm, and BAC severity all factor into the board’s decision.
Crossing Into Canada
Canadian immigration law classifies impaired driving as a serious crime, and even a single DUI conviction, including a misdemeanor, can make you inadmissible at the border.6Government of Canada. Overcome Criminal Convictions This applies at airports, land crossings, and seaports.
Workarounds exist but aren’t quick. A Temporary Resident Permit allows entry for a specific trip if you can demonstrate your need outweighs the security risk, but the application runs 50-plus pages and requires documentation of every arrest in your past. For a permanent solution, you can apply for Criminal Rehabilitation, but only after at least five years have passed since you completed your entire sentence, including fines, probation, and license suspension.
Getting the Conviction Off Your Record
True expungement, where the conviction is erased as if it never happened, is rare for DUI offenses. Most states that offer relief use record sealing or a “set-aside” process instead, which hides the conviction from standard background checks without destroying the record. Courts, law enforcement, and some licensing boards can still see a sealed record.
Eligibility for sealing typically requires completion of all sentence terms, including probation, fines, treatment, and license reinstatement. After that, most states impose a waiting period of three to ten years before you can file a petition. Aggravating factors like a high BAC, repeat offenses, or an accident involving injuries can make you ineligible altogether. Where sealing is available, it’s worth pursuing, since the conviction’s effect on employment, housing, and licensing can outlast the criminal penalties themselves.