Tennessee DUI Laws

Tennessee has a 0.08% per se limit: driving with a blood or breath alcohol concentration of 0.08% or more is DUI. But 0.08% is not the whole law. Tennessee also prosecutes driving while impaired by alcohol, marijuana, a controlled substance, or any central-nervous-system substance, with no test result needed, so a driver below 0.08% can still be charged. Commercial drivers are DUI at 0.04%, and drivers under 21 face a separate offense at 0.02%.

A first DUI is a Class A misdemeanor. It carries a mandatory minimum of 48 consecutive hours in jail (served day-for-day) up to a maximum of 11 months and 29 days, a fine of $350 to $1,500, and a one-year license revocation. Most first offenders also face ignition-interlock and restricted-license conditions, plus a mandatory fee stack on top of the fine. A child under 18 in the vehicle adds 30 mandatory days and a $1,000 fine.

For a first DUI, a BAC of 0.15% or more raises the mandatory minimum jail time from 48 hours to 7 consecutive days; the rest of the first-offense penalties stay the same. That 0.15% is the only enhanced number inside the DUI statute itself. A separate 0.15% trigger, lowered from 0.20% on July 1, 2025, elevates the aggravated vehicular-assault and aggravated vehicular-homicide crimes when the driver also has a qualifying prior.

A second DUI is a Class A misdemeanor with a 45-day mandatory minimum (served day-for-day; treatment can be ordered only after 17 days are served) up to 11 months and 29 days, a fine of $600 to $3,500, and a two-year license revocation with mandatory ignition interlock. The vehicle can also be seized and forfeited if at least one prior conviction is within five years.

A third DUI is still a Class A misdemeanor, but it carries a 120-day mandatory minimum (served day-for-day) up to 11 months and 29 days, a fine of $1,100 to $10,000, and a six-year license revocation. At a third or subsequent offense you must pay all ignition-interlock and monitoring costs yourself, with no indigency assistance.

The fourth DUI is the first felony tier — a Class E felony with a 150-day mandatory minimum and up to 6 years, a fine of $3,000 to $15,000, and an eight-year license revocation. A fifth offense (with at least four priors, on or after July 1, 2019) is a Class D felony punishable by up to 12 years, and a sixth or subsequent (with at least five priors, on or after July 1, 2016) is a Class C felony punishable by up to 15 years. The 150-day figure is a mandatory minimum; the maximums come from the general felony-sentencing statute, not the 150-day floor.

The base lookback is 10 years, but it works as a chain: you are a multiple offender if your last violation was within 10 years of the current one, and then every prior within 10 years of the next-more-recent violation counts. Nothing older than 20 years from the current offense ever counts as a prior — except that a prior vehicular-assault or vehicular-homicide conviction counts no matter how old. Boating-under-the-influence and out-of-state equivalents count, and pre-2003 adult-driving-while-impaired convictions still count even though that offense was repealed.

The court prohibits driving for one year on a first offense, two years on a second, six years on a third, and eight years on a fourth or subsequent offense. Tennessee treats this as a revocation, not a suspension, so you must apply for a new license at the end — and after a second or subsequent DUI you must also show proof of completed alcohol or drug education or treatment. A restricted license, usually with an ignition interlock, may be available under section 55-10-409.

Usually, yes. The judge must order interlock as a condition of a restricted license when, at the time of the offense, there was a measured BAC of 0.08% or more (or an alcohol-plus-drug combination), a child under 18 in the vehicle, an intoxication-caused crash, or a qualifying refusal; a prior DUI within 10 years also forces interlock for the entire restricted-license period. Because the per se limit is itself 0.08%, most drivers with a test result get interlock; an impairment-only conviction with no measured BAC is the main exception. The device is calibrated to lock out at 0.02%.

Refusing is a civil implied-consent violation, not a crime, so it means license revocation rather than jail: one year for a first violation — 18 months for a first blood-test refusal in a misdemeanor DUI case on or after January 1, 2026 (Public Chapter 403); effective January 1, 2027, the 18-month period applies to all first-time refusals (Public Chapter 1046) — two years with a qualifying prior or a serious-injury crash, and five years for a fatal crash. As of January 1, 2026, the tests include oral fluid (saliva), and a refusal still counts even if officers later draw blood under a warrant. A refusal can also be used against you in the DUI case.

A driver under 21 with a BAC of 0.02% or more, or who is impaired, commits underage driving while impaired, a lesser-included offense with its own penalty rather than the adult DUI grid. For 18-to-20-year-olds it is a Class A misdemeanor punishable by a one-year license suspension, a $250 fine, and possible public service work. Under 18, it is handled as a delinquent act with the same penalties.

Yes. Tennessee DUI covers impairment by marijuana, controlled substances, or any central-nervous-system substance, alone or combined with alcohol. There is no per se THC or drug blood level in the DUI statute — these cases are proven by impairment, not a number — and being lawfully entitled to use a drug, including a valid prescription, is not a defense. From January 1, 2026, implied consent includes oral-fluid (saliva) testing aimed at drugs.

Those are separate, more serious felonies. Causing serious bodily injury is vehicular assault, a Class D felony; with qualifying priors or a BAC of 0.15% or more (lowered from 0.20% on July 1, 2025) it becomes aggravated vehicular assault, a Class C felony with a $5,000 to $15,000 fine. A death is vehicular homicide by intoxication, a Class B felony, or aggravated vehicular homicide, a Class A felony. Separately, having a child under 18 in the car adds 30 mandatory days and a $1,000 fine, and serious injury or death to that child is itself a Class D or Class B felony.